Geo-information Tools
29/10/2018 - Week 1 Day 1
Module 1
1.2 What is a the difference between a feature class and a feature dataset?
Feature classes are homogeneous collections of common features, each having the same spatial
representation, such as points, lines, or polygons, and a common set of attribute columns, for example,
a line feature class for representing road centerlines. The four most commonly used feature classes are
points, lines, polygons, and annotation (the geodatabase name for map text).
A feature dataset is a collection of classes with the same map projection, coordinate system properties,
tolerance values, etc. This can only be made in a geodatabase.
1.3.1 What are the main components?
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Pre-processing data: 1. Collection data;
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Find the best path : 1. Water Body; 2. Elevation Model; 3. Distance; 4. Population size
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Edit : Corrected the best path
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Cost : calculate the cost including noise barriers, bridge
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Visualize : create maps
1.3.2 Using your basic knowledge of GIS, what type of GIS data handling types do you think you will
need to accomplish the first project component?
●
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Queries, Transformations and Process/Alter Operations
Queries:
Query is a term coming from database information systems. It stands for QUEstion and ReplaY. Queries
create a subset of the original data input. This means the described information does not change. For
example, the attributes and the domain values of the attributes of a dataset does not change when using
a query.
Basically there are two types of queries in GIS. A query based on logical expression using attribute
information. For example, select all polygons where LanduseCode = 'forest'. The logical expression in this
example is LanduseCode = 'forest'. A spatial query is the other basic query type. For example, select all
buildings within the municipality of Wageningen.
Transformations:
In GIS, transformation are related to geometric change. The original definition of the data does not
change with this data handling type.
Examples are:
- coordinate transformations. For example transforming the data from the Geographic map projection in
defined in degrees to WGS84 in meters.
- format transformation. For example, vector to raster and vice versa
- attribute values transformation. For example, translating landuse values in Dutch to English
Process/Alter:
This data handling type changes the input information into new information. For example, making a
buffer around the design light rail that represents a walking zone. Also, spatial overlays where the
information of input data is joined to one another by means of there location. For example, using the
Union spatial overlay to create one dataset of landuse and soil, belongs to this data handling type.
1.4.1 What is the fundamental purpose of GeoProcessing according to ESRI?
●
The fundamental purpose of geoprocessing is to provide tools and a framework for performing
analysis and managing your geographic data. The modeling and analysis capabilities
geoprocessing provides make ArcGIS a complete geographic information system. This allows you
to repeat calculations and also share your workflow with others.
1.4.2 What does GeoProcessing allow you to do within ArcGIS?
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provides a large suite of tools for performing GIS tasks that range from simple buffers and
polygon overlays to complex regression analysis and image classification.
1.4.3 What is a script tool according to the essential GeoProcessing vocabulary of ESRI?
●
These tools are created using the Script tool wizard and run a script file on disk, such as a
Python file (.py), AML file (.aml), or executable (.exe or .bat).
1.4.4 What is a toolbox? What is the difference between system- and custom toolboxes?
●
Toolbox are simple organization folders, just like folders on your system. Tools cannot be stored
in anything but a toolbox. Like tools, there are two categories of toolboxes, system and custom.
1.4.5 What are GeoProcessing environments?
●
Environment settings can be thought of as additional parameters that affect the execution of a
tool.
1.4.6 There four different levels of setting GeoProcessing environments. What level settings are there?
There are four levels of environment settings
●
Application level settings are the default settings that will be applied to any tool when it is
executed.
●
Tool level settings are applied to a single run of a tool and override the application level settings.
●
Model level settings are specified and saved with a mode and override tool level and application
level settings.
●
Model process level settings are specified at the model process level, are saved with the model,
and override model level settings.
Module 2 is a exercise (We also need to answer the the first part questions)
10/29/2018
Module 2 (We forgot to do it at the first day)
2.1.1
What are the names of the toolsets in the toolbox?
● First level: a_General_project_preprocessing_tools
What is the name of the only tool found in this toolbox?
● Second Level: a0_special_comp_scripts
Select the tool and click the right-hand button of the mouse. Select the edit function to see the
content of the tool.
Is this an ArcGIS model or a programming script?
● Yes
If it is a script, what scripting language is used and for which version of ArcGIS was it made?
● These tools can be copied to the project application toolbox to make sure they are accessible
after the end of the project. This is necessary to guarantee the repeatability even after the
project has ended.
2.1.2
How many:
Model Input Datasets are there?
● 6 input datasets are all blue. (Light blue is not one of them)
Model Output Datasets are there?
● 5 outputs datasets are all green at the bottom.
Model Intermediate Datasets are there?
● 6 model intermediate datasets are green except the bottom greens.
Processing Actions are there?
● One, the bottom yellow one.
Option Input Parameters are there?
●
Yes, the light blue one
What are the prefixes of the datasets?
●
●
a9 : Component A step 9
ps: project source
To which type of project application category does each dataset belong to?
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All are from project geodatabase
Meaning of GIS-operations:
●
●
●
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Select: Queries
Clip: Queries
Multi to Singlepart: Transformation
Topo to Raster: Process
2.1.3
After reading "The need for notations", how many Geodatabase(s) do you require for your light
project? ---- Three
●
●
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Data that you need to save at the end of the project to reproduce the project outputs.
Data that is needed during the project to connect the component and steps phases.
Data that can be considered intermediate results during one model computation.
What names do you proposes for your Geodatabase(s)?
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●
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IA_Lightrail_1_project_gdb
IA_Lightrail_2_component_gdb
IA_Lightrail_3_step_gdb
What name do you propose for your light rail application toolbox?
●
00_IA_Lightrail_Aplication_<name_application_developer(s)>
What names do you propose for the first two application components?
●
●
a_preprocessing
b_compute_lightrail_route_and_corridor
30/10/2018 Week 1 Day 2
Module 3
3.1 Setting Up working environment
Where do we store our temporary processing data?
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Arcmap-Customize-Arcmap options-display cache/data interoperability
3.2.1 Extension
What is Extension?
●
Extensions are extra program functionality that you buy separately.
3.4.1
What are the name and the extension of the toolbox file, when observing it with Windows Explorer?
●
IA_lightrail_application_YueandLia.tbx
To which project application level does the created toolbox correspond?
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Application
3.4.2
To which project application level does the created toolset "a_preprocessing" correspond?
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Application
3.4.3
What is a workspace?
●
the location of a folder that locates the contents of a shared geoprocessing package or service.
What is the difference between current and scratch workspace ?
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Current workspace:Tools that honor the Current Workspace environment setting use the
workspace specified as the default location for geoprocessing tool inputs and outputs
●
Scratch workspace :Tools that honor the Scratch Workspace environment setting use the
specified location as the default workspace for output datasets. The Scratch Workspace is
intended for output data you do not wish to maintain.
Why is it wise to set an output coordinate system within a Gis Project ?
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To standardize the input data raster, hence it will have the consistent coordinate data which is
essential when creating maps.
●
For projects interaction, if we have the same coordinates system for their output, we can easily
to do operations together.
What type of changes to an output dataset can you expect when this transformation is applied to an
output vector and raster dataset?
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Vector changes:Transforming a vector dataset will basically reproject the most primitive feature
elements, a point, from one coordinate to another. So the shape and location of a feature will be
changed. The same happens when tranforming lines and polygons, the points of which the lines
and polygons are build, are reprojected from one coordinate system to another, and the lines
and polygons are reconstructed.
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Raster changes: Transforming raster datasets will change the content of the dataset, as the
values of a rastercell will be aggregated or desaggregated. The resampling method usewd is
very important, and depends on the datascale of the raster datset.
What is the difference between XY Resolution and XY Tolerance?
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XY resolution: refers to the number of significant digits used to store x,y coordinate value
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The x,y tolerance: refers to the minimum distance between coordinates before they
are considered equal.
What is the difference between M values and Z values?
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M values : M is relative measures along a line that can represent any unit of measure.
●
Z values: Z is elevation.
M-values (Measure values) are related to lines that form a route in a network system. Route's geometry
differs from other linear geometry in that instead of being a collection of x,y coordinates, a route's
geometry is a collection of x,y,m values. In the following example, there is a route that is 110 miles long in
the real world. Displaying such a route on a map might look something like this.
A route's geometry is a polyline with measures.
The vertices that make up this polyline might look something like this.
Module 4
4.2.1
What is an MXD file ?
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A connection of all datasets in the file.
Does an MXD file contain the actual data ?
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No
Do all your coordinates fall inside the extent of the dataset GEOTOOLSDATA.HeightContourLines?
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No, not all of them, especially for the eastern part.
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Minimum X: 161000m ; Minimum Y: 438000m
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Maximum X: 179000m ; Maximum Y: 452000m
What is the perimeter (border length) and area in meters? (This area will be the project extent of the
lightrail project.)
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Perimeters: 68,398.7172m
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Area: 76,116,434.9385m2
4.2.2
What is the script filename?
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IAa1stCreateAClipboxFeatureForProject
What are the scripts parameter names and their corresponding Data Types?
Output Clip Feature : Feature Class
Xmin : Any value { This means any numeric value can be given. }
Ymin : Any value { Therefore integer values (for example 401500) or }
Xmax : Any value { Real values (for example 401500.00) can be used }
Ymax : Any value { as an input value for the XY min/max coordinates }
Coordinate System : Spatial Reference
(If you need to check, put it bigger)
Why do you think this difference exists?
●
The difference between double clicking a model and drag and drop it on a model is its
repeatability.In the first case, the model parameters need to be added each time the tool is
used. The tool is used with a graphical user interface GUI.
●
When using a tool in a model, the parameter values will be saved in the model and the modelactions can be repeated with exactly the same environment- and in- and output parameters
settings at any moment.
Is the clipbox boundary correct? If not, change the XY coordinates in your model and re-compute the
ps_project_clipbox.
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No, we did change it again. (Plus, we need to decrease XY coordinates when it comes to
minimum)
Compare the perimeter length and surface area you've calculated in the previous part of Module 4 with
the ones given in the Attribute table. Is there a difference?
●
Yes, they are different, especially for area.
31/10/2018 Week 1 Day 3
Module 4
4.2.3
Although the CLIP operation combines two feature dataset to create a new (geometrically altered) output
feature class; why is a CLIP feature operation not considered a spatial overlay operation?
The CLIP operation is a spatial query operation. It selects features within a given area. The original
feature/object definition does not change. This means the attributes of each feature stays the same.
A spatial overlay on the other hand, JOINS the object definitions of both input feature classes. This
joining operation create a new object definition, the combined attributes of both input feature table. Due
to the entity change you create new features with a new object definition. Using a spatial overlay when
you should use a spatial query can have severe consequences in your project. For example, redundant
attributes in your output dataset. This can cost a lot of extra computation time and storage space. This
could result in long delays when applying when applying your results later in the project.
What are the coordinate extents of the clipped dataset? Check by looking at the properties of
psa2_MunicipalityBoundaries and use the Source tab.
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Extent
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Left : 161000.000000 m
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Top : 452000.000000 m
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Bottom : 438000.000000 m
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Right : 179000.000000 m
Why are all the clipped datasets considered to be “project source” ps??_) datasets?
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Even we clipped the project resource but they are still resource instead of output datasets
Why does ps_elevation_point not have an attribute SHAPE_LENGTH?
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Point features do not have a length and/or area, it is just a x-y position.
Why is the attribute SHAPE_LENGTH or GEOMETRIE_LENGTH kept in the other datasets?
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It represents the attribute of datasets, which is fixed. If we really need to delete them, we will
get an error while running the model.
Which tool computation took the longest calculate time?
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Delete Field and drop field
What type of processing operation is Clip? (query, transformation or alter)
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Query
What type of processing operation is Delete Field? (query, transformation or alter)
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Query
Notes:
psa2_streamlines
TYPEWATER, RuleID, Override
It seems that I forget Override here.(It is hidden)
01/11/2018
Module 4
4.2.4
Why is it not necessary to give a Summary Field?
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If a summary field is specified, the unique attribute values of the frequency calculation are
summarized by the numeric attribute values of each summary field.
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For example if you want to sum the area according to each individual TDN_CODE. TDN_CODE is
the Frequency Field and Shape_Area is the Summary Field.
Why is LONG an appropriate Field Type in this case?
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LONG means long integer
Why do you think this is necessary?
●
There are so many steps that we are running, which can help us to identify which file is for the
result.
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When adding a field you change the structure of a table. This means you do not create a new
table but alter the table. Therfore the input table is the output table but with a new attribute.
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In ArcGIS when you apply any "FIELD tool" the input table and output table will always be the
same.
Why is this "remove intermediate model option" not desired during application development?
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When you run a model, output data is created for each process in the model. Some of the data
created is of no use after the model is run since it was only created to connect to another
process that creates new output. Such data is called intermediate data. All outputs except the
final output, or those that have been made model parameters, are automatically made
intermediate data in the model. In this example, the output of the Buffer tool is only useful as an
input to the Clip tool and is not used after that, so the Intermediate option is checked. You can
choose to save the intermediate data by unchecking the Intermediate option.
Why are some other output data boxes have a greyed out Intermediate option?
●
Because new output files will replace the previous one
What does this model actually make?
●
Filter and reclassify by TDN_CODE, at the same time delete the redundant data. This model
merges all individual reclassifications tables created from each top10 polygon feature dataset
into one project reclassification table. This basic reclassification table is used later to assign each
top10 feature polygon a suitability weight. These suitability weight factors are used to compute a
so-called "cost" path and cost corridor from Ede to Wageningen en vice versa. This will be
discussed in further detail in Module 12.
What does the MERGE tool do?
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To represent a grouped of merge collection of rasters to be a single items. For example, to
calculate several statistics data at the same time.
Where did you save the table a4_merged_freqency_tables and why?
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IA_3_step Geodatabase; Because as the question said, it is a step result.
Where did you save the table ps_basic_reclass_table?
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We saved the table in IA_1_project Geodatabase.
The previous table starts with ps. What does this stand for?
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Project source.
05/11/2018
Module 5
5.2
What are the standard geometric attributes for the 3 different features types (Polygon, Line, and Point)?
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Polygon : Shapearea, (area unit),Shape_length
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Line : length (length unit), Polyline
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Point :(coordinate unit), Point
What are the user-defined attribute(s) of the datasets ps_landcover and ps_infrastructure? Use the
Catalog browser or ArcCatalog to find out which attributes the user defined.
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ps_landcover: TDN_CODE
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ps_infrastructure: TDN_CODE
Why is the following attribute table not possible in ArcGIS?
Combined geometric feature classes are not allowed. It is only possible to have one geometric type in a
feature dataset.
What does the field OBJECTID represent?
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it represents the identify rows in tables in a geodatabase,which is like order for dataset.
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An ObjectID is a unique, not null integer field used to uniquely identify rows in tables in a
geodatabase. ObjectIDs are limited to 32-bit values, which store a maximum value of
2,147,483,647.
Tables that are created through ArcGIS, or created outside ArcGIS then registered with the
geodatabase, automatically have an ObjectID field added to them. The values in this field are
maintained by ArcGIS. The ObjectID is used by ArcGIS to do such things as scroll, display
selection sets, and perform identify operations on features.
In relational database management systems (RDBMS) a field is referred to as:
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Column
In relational database management systems (RDBMS) the three fields combined is referred to as a(n):
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Class
In relational database management systems (RDBMS) a table row is referred to as a(n):
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Object
In relational database management systems (RDBMS) the intersection of a row and column in a table is
as a(n):
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Value
This table can be connected (joined) to a TOP10NL feature dataset. One row of this table is used to
describe many features in the joined feature dataset. How is this row referred to in GIS?
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Class
The following overview shows the table properties of the previous table.
What is the difference between Field Name and Alias?
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Field names: in the same table must be unique; for instance, you can't have two columns with
the name ObjectID. Field names are the names you give to the columns in a table. The names
should give an indication of what data is contained in that particular column.
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Alias:When you create a table or feature class in a geodatabase, you can assign an alias to it. An
alias is an alternate name. If you assign an alias to a table or feature class, that is the name
users will see when they add it to the map. Users can still look up the name of the table or
feature class by going to the Source tab on the Properties dialog box.
When you create a new feature class or table in a geodatabase using geoprocessing tools, there
is no parameter to specify the alias. You can set an alias for the feature class or table on the
Source tab of the Properties dialog box. Right-click the feature class or table on the Catalog
pane, select Properties, click the Source tab, and single-click the Alias property to enable editing
of the name. Type an alias name and click OK to set an alias for that feature class or table.
It can be the same name for different fields.
Can an Alias Field Name be used in a Query expression in ArcGIS?
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Definition: Field aliases allow you to assign an alternate name for a field. You normally use field
names that are as short as possible to convey what data is stored in that field. You also cannot
use spaces or special characters in the field name, and as shown above, certain fields show up in
the table with their fully qualified names. In these cases, you could use a field alias to give the
field a more descriptive name. For example, if you had a field named ST_SUFX that stored the
type of street, which was indicated by the suffix used on the street name, you could give this
field an alias of Street name suffix.
●
it can , because the aliases field will not affect the expression syntax. Field aliases will not be
shown or supported in the expression itself. If you double-click a field alias, it will still be added
into the expression with its actual field name and any required [ ] field delimiters.
5.3 Create a table
How many bytes does a short integer contain and what are the minimum and maximum integer values
that can be stored in this data type?
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Bytes size : 2
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Min : -32,768
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Max : 32,767
How many bytes does a long integer contain? Can the height of the Mount Everest be saved in a long
integer data type when the height of the Mount Everest must be expressed in 1000ths of a millimetre
(µ's)?
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Bytes size : 4
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Min :-2,147,483,648
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Max : 2,147,483,647
Someone wants to store the municipality code number of the Netherlands. The code numbers range from
10 to 999. What data type is best used?
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short integer
Someone wants to store height as whole numbers. The last digit represents millimetres. The height
range (domain) is -12,000,000 to 9,000,000. What data type is best used?
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Long integer
What data type is best used to calculate results that can have a very big number with 15 digits precision
behind the decimal place? For example the number 123456789.123,456,789,012,345
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Double (double precision floating-point number
When would you use a Blob data type?
●
A Binary Large OBject (BLOB) is a collection of binary data stored as a single entity in a
database management system. Blobs are typically images, audio or other multimedia objects,
though sometimes binary executable code is stored as a blob.
●
A BLOB is data stored as a long sequence of binary numbers. ArcGIS stores annotation and
dimensions as BLOBs, and items such as images, multimedia, or bits of code can be stored in
this type of field.
The spreadsheet contains information about 3 different levels of administrative features. One feature
class is the municipal neighbourhood (called Buurt in Dutch). What are the other two administrative
features in the spreadsheet?
Gemeentecode: The municipalities in the Netherlands are subdivided into neighborhoods and
neighborhoods. Neighborhoods are the lowest regional level. Districts are summations of one or
more contiguous neighborhoods. The municipality itself determines the division into
neighborhoods and neighborhoods. Statistics Netherlands coordinates this classification
nationwide.
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Wijkcode: Part of a municipality in which a certain form of land use or building predominates.
For example: industrial area, residential area with high-rise or low-rise buildings. A
neighborhood consists of one or more neighborhoods.
Which attribute describes the unique identifiers for neighbourhood information?
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BU_CODE
Which attribute is the most appropriate to link the information in the spreadsheet to the feature class?
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code
What is the neighbourhood code for the neighbourhood "Oude Stad Binnenstad"(Old city downtown) in
the municipality of Wageningen?
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BU02890000
What are the attribute names in both the neighbourhood feature class and the spreadsheet, on which the
relation between the two tables can be made?
●
●
●
the neighbourhood feature class:
○
BU_NAME
○
BU_CODE
○
WK_CODE
○
GM_CODE
○
GM_NAAM
the spreadsheet:
○
Neighbourhood Name
○
Municipality name
○
Coding
○
Number Inhabitants
○
Population Density
○
Total Households
○
Average Household Size
We can join the two tables based on BU_CODE and Neighbourhood Name, because they follow
the same naming rules.
5.3.3
Now that you have gained experience in making a table from a worksheet layout, state 3 differences
between an excel worksheet and a table.
Spreadsheet
Table
cell based
row based
no fixed structure
fixed structure defined by columns (attributes/fields)
This fixed structure is also called entity or object
definition
can have a formula as well as values in a cell
can only save values. It is possible to have formulas
but this is only supported in a table view.
no fixed query language applicable
tables in relational databases very often use a
standard query language like SQL
Explain in your own words what the expression "Coding" LIKE 'BU%' does.
●
It means that “Coding” column in the worksheet is the same as BU… in attribute tables.
Why is the parameter "Sheet" in the above model not used as an input for the other two Excel to Table
tools?
●
Because we are using the different sheet, the inputs are different. We have to create another
“Sheet” parameter for other sheets.
Why is the parameter "Field Name" in the above model used three times as an input for the tool Add
Field tools?
●
We are using the tool---Add Field, which means that the attribute table will be added one more
column, meanwhile, we need various year for data. Thus we need put all data in the same
column. That’s why we need use same “Field Name” several times.
In which Geodatabase did you save the first tables coming directly from the Excel sheet?
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I saved the first tables in step result.
What storage data types are used in the table attributes?
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Standalone Table
●
There are only 2 storage datatypes you can expect; Double precision floating point and text. In
modern databases the need to differentiate in number data storage types is declining. Storage
space is no longer an issue. However the number of attributes/fields is. The transaction time of
records during a query is highly dependent upon the number of attributes. It is therefore good
practice to get rid of redundant attributes is a table.
Do these data types correspond to the original data-types you defined in the Excel file?
●
●
Depending upon the region setting of your computer number attributes can automatically
change to text. For example in the Dutch setting a decimal point is represented by a comma. In
the table conversion from spreadsheet to table in a geodatabase this attribute will become text
instead of a number.
Do all tables have the same attribute names?
●
Yes
In which geodatabase did you save the table psa5_CensusData? Why?
●
1 Project Geodatabase; Because census data is related to population and it is project source
data.
5.4 Joining & Relating tables
What relationship type is created between the neighbourhood feature class table and the demographic
tables you have imported from Excel?
●
1:1
What are the key attributes to relate both tables?
●
Coding and BU_CODE
06/11/2018
Module 5
5.5 Joining the table
As stated, the result shows a one to one relationship, which demographic year is used?
●
At the beginning, only 2012.
In which geodatabase did you save a6_neighborhood_popyear? Why?
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3_stepresult
In which geodatabase did you save a6_nb_popyear? Why?
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2_component
What is the expression you used to select the correct features with the select tool?
●
I haven’t finished this one yet, but I will figure it out later.
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"GWB_CODE" IS NOT NULL
Do you have redundant or duplicate attributes in your new neighbourhood attribute table?
●
Yes, I do have redundant attributes data, such as the name of city...
How do you know which population density belongs to which year?
●
I put Census year behind attributes
5.6 Correct attributes names for Demographic data
Why the need to copy psa2_Neighbourhoods before the join calculation?
●
It makes sure that we won’t ruin our resource data
In which GDB did you save the polygon feature data a6_nb_popyear?
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2_Component
In which GDB did you save the polygon feature data psa6_NeighbCensusData?
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1_project
Is the population in the centre of Wageningen increasing or decreasing?
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The population in the centre of Wageningen is increasing from 2012 to 2014
Are there results that do not make sense? For example extreme decreases or increases?
●
Because there are several values that are -9999 or null, it influences the result.
What do you think the reason is for these extreme decreases or increases?
●
With the students number increasing.
(The left side is Total Population Per Neighborhood; the right side is Population Density)
5.7 Relating tables
How many records are selected?
●
In my case, I have 14 selected by me.
How many records are selected?
●
42
Explain why the demographic table has more selected records than the feature class attribute table.
●
Because it has 3 years data of the same place, as we can see here, 14 * 3 = 42
5.8 Joining descriptions to the reclassification table
Which of the incoming dataset needs to be copied first, and why?
Before running the model, I think ps_basic_recla has to be copied, which is our resource data and also
basic reclassification data. We should not edit the original one.
Where did you save your final result?
I saved my result in 1_project
What name did you give this dataset (table)?
psa4_basic_reclas_table_with_meaning
07/11/2018
Module 6
6.2
What is a table view?
●
Provides access to basic table properties.
●
Feature layers and table views have the same function in ArcGIS.
●
A (feature or Raster) layer is what you see in the ArcMap table of contents. A layer contains the
path to the dataset along with symbology information and feature or row selection information.
●
Table views are the table equivalent of a layer. In principle they point to the selected records in
the related table.
Where are the table view selections saved?
●
●
They are stored in memory and are the same as the table view created when a table is added to
ArcMap.
What happens to table view selections when you exit ArcMap?
●
I guess they will be canceled.
6.3 Joining suitability to the lightrail application requirements
Why does the Join Field calculation take so long in comparison to the Copy Features calculation?
●
Because we need calculate one layer by one layer, and the feature classes are a lot.
●
Every feature (row in the feature attribute table) is altered (the original plus the new joined
attributes) to create a new entity. This means the row is read (selected), altered and thereafter
written to the file. Any Copy tool only reads (selects) and writes; no alteration are made to the
existing data.
08/11/2018
Module 7
Find the help page: Learn more about how Topo to Raster works
What is the name of the programme Topo to Raster is based on and when was it developed?
●
The Topo to Raster tool is an interpolation method specifically designed for the creation of
hydrologically correct digital elevation models (DEMs). It is based on the ANUDEM program
developed.
Who was the developer of this programme?
●
by Michael Hutchinson
A specific interpolation technique is used to determine the terrain surface. Which one is it?
●
It is essentially a discretized thin plate spline technique (Wahba, 1990) for which the roughness
penalty.
This technique has been modified to do what?
●
To allow the fitted DEM to follow abrupt changes in terrain, such as streams, ridges and cliffs.
What is the purpose of the drainage enforcement process?
●
The purpose of the drainage enforcement process is to remove all sink points in the output DEM
that have not been identified as sinks in the input sink feature dataset.
●
Drainage enforcement can also be supplemented with the incorporation of stream line data. This
is useful when more accurate placement of streams is required.
What is a sink in a hydrological model and why are these important to know?
●
A sink is usually an incorrect value lower than the values of its surroundings, since sinks are
generally rare in natural landscapes.
●
It is important to know to ensure proper drainage mapping because sink can affect the
depression of DEM original data.
●
The drainage enforcement algorithm attempts to clear spurious sinks by modifying the DEM,
inferring drainage lines via the lowest saddle point in the drainage area surrounding each
spurious sink. It does not attempt to clear real sinks as supplied by the Sink function. Since sink
clearance is subject to the elevation tolerance, the program is conservative when attempting to
clear spurious sinks. In other words, it does not clear spurious sinks that would contradict input
elevation data by more than the value of Tolerance 1.
There are nine type of feature dataset inputs possible when using the tool Topo to Raster. Which inputs
require a height field?
●
There are nine types of data accepted inputs to the Topo class: TopoPointElevation,
TopoContour, TopoStream, TopoSink, TopoBoundary, TopoLake, TopoCliff, TopoExclusion, and
TopoCoast.
What is a STREAM line feature input? When would you use this input in Topo to Raster?
●
Defines a list of line feature classes of stream locations.
●
All lines must be oriented to point downstream.
●
The feature class should only contain single line streams.
●
To display the direction of the line sections, change the Symbology to the Arrow at End option.
This will draw the line sections with an arrow symbol showing the line directions.
What is a Multipoint feature? (Search for Multipart to Singlepart)
●
These are called multipoint features for point or multipart features for line and polygon features.
Mass point observations from lidar data are often represented in a feature class with multipoint
geometry. A feature that one more physical parts in one attributes.
What do you see the most negative height difference? Explain in your own words why this is the case.
●
The most negative height difference is 58
Where is the least difference in height? Explain in your own words why this is the case.
●
What is the name of your adapted model?
●
b?st_something
12/11/2018
Module 8a
To use this table with a pig farm feature dataset, a common attribute in both the feature class table and
the presented table above are required. Which attribute do you think it is?
●
Type of Pig farm which indicates if a farm has stench filter
Which ArcGIS tool can you use to connect both tables?
●
Join Field
Which ArcGIS tools are required to create the new attribute and give content?
●
Add Field and Calculate Field
There are three datasets involved in this example:
- The pig farm locations
- The Restriction zone buffer distance table
- The Restriction zone area
To which dataset should you create the new attribute and content?
●
The Restriction zone area
In which GDB must you save these two datasets?
●
Step results?
How many records does the attribute table have?
●
258 (None dissolve)
How many records does the attribute table have?
●
258
How does the buffer differ in geometry and thematic sense in the previous results?
●
In the first method, the method created a buffer around every polygon feature. In the attribute
table the TDN_code and the buffer distance were included.
●
The second method, created a buffer around every Shape_area class value. In the attribute table
the Shape_area was present, but no buffer distance attribute. In principle, all buffer polygon
features of the first solution were dissolved according to Shape_area value.
●
The third method created one buffer and only geometric attributes. No thematic attributes.
Explain in your own words what the DISSOLVE option does during the buffer computation.
Use ArcGIS's help "How Dissolve (Data Management) works" to find more information.
●
Dissolve aggregates features based on specified attributes.
Which Buffer solution is required in the lightrail project concerning preferred construction area around
main and secondary roads? Motivate your answer
●
List is the best dissolve feature in kind of project because it results three tdn_code which is
needed, instead of al data for NONE and only one for ALL.
Explain in your own words what a precondition connection in the model builder does
●
Precondition means that the model has to run the precondition firstly then go to another
function.
Why is this precondition necessary in this model?
●
Otherwise, there is no LR_WGT here yet.
13/11/2018
Module 8b
Describe in your words what the three Euclidean tools do:
●
Euclidean Allocation: Calculates, for each cell, the nearest source based on Euclidean distance
●
Euclidean Distance: Calculates, for each cell, the Euclidean distance to the closest source
●
Euclidean Direction: Calculates, for each cell, the direction, in degrees, to the nearest source
The three presented Euclidean results are drawn according to an attribute data scale. Attribute data
scales are: Nominal, Ordinal, Interval, Ratio or Binary.
Firstly per Euclidean result determine whether the grid has an attribute table or not. Use the help of
ArcGIS and explain why some grids have an attribute table and others do not.
●
When the input source data is a raster, the set of source cells consists of all cells in the source
raster that have valid values. Cells that have NoData values are not included in the source set.
The value 0 is considered a legitimate source. A source raster can be easily created using the
extraction tools.
What is the data scale of the drawing attribute in the grid made by:
●
Euclidean Allocation: Depends on the labels?
●
Euclidean Distance: Nominal
●
Euclidean Direction: Interval
What is an ASCII text file?
●
An ASCII remap file can be created with any editor that will produce an ASCII text file. Following
is some discussion about correctly formulating the ASCII file to use.
For the Reclass by ASCII File tool, the input remap file must be formatted in a specific way. The
file can be created in any editor that will produce an ASCII text file.
The following list provides some details on the correct formatting for the ASCII file:
Comment lines can be entered beginning with the # symbol. There are no limits to the number
of comments that can be entered.
Each assignment line maps a value or range of values from the input raster to an output value.
Only numeric values are accepted on an assignment line.
All assignment lines in an ASCII remap file must be in the same format. Two formats are
supported: one for reclassifying individually specified input values, the other for reclassifying
ranges of input values.
●
200 250 : 50
251 299 : 20
Explain why this solution with a Reclass ASCII File is not preferred in a GIS project.
●
FIrst of all, it is difficult to type all the values one by one if we have a big dataset
●
Then, we cannot describe something that are not a numerical label
The Constant Raster output has the same cell size as the Euclidean Allocation outputs. The Euclidean
outputs have the data type ‘float’. Why is it necessary that the output of the tool Constant Raster have
the same data type?
●
A floating point raster. Each cell will have as a value the distance to the closest input point
(Source). The extent of the output is equal to the extent of the input feature class.??
Why is the output of the Constant Raster tool given the value of -9999?
●
It is helpful when we run the model “CON” because then we have conditional statement to
identify the different cells.
Explain in your own words what the Mosaic tool does?
●
Merges multiple existing raster datasets into an existing raster dataset
Why does the Mosaic Operator need to be set to Maximum?
●
Because the default we set up is -9999, it means that when the cell value is not -9999 we need
take this value. In this case, we will always have cell values that are larger than -9999. Thus, we
need to choose the option “Maximum” to take the maximum value.
What raster value does the red colour represent?
●
Red color parts represent main roads and secondary roads, which also means that raster values
are equal to 3.
What raster value does the white colour represent?
●
White color means that cell values are -9999
What does the ~IsNull mean in your own words?
●
ISNULL means the raser value is Null, which can be nothing in this case.
ALTERNATIVE SOLUTIO: Raster Calculator
Module 9
Explain what the purpose is of each action in this test model. Also explain which "simplification tolerance
distance and area" combination you would use in this project. The values you choose can be different
than the given used in this example. Use the ArcGIS help to find background information.
●
Select: We wanna only select the neighborhood in Wageningen
●
Clip: Use the neighborhood to clip buildings in Wageningen near neighbourhood
●
Simplify Building: Simplifies the boundary or footprint of building polygons while maintaining
their essential shape and size.
Explain in your own words what the purpose is of this aggregation action in the model. Also explain
which "aggregation distance, minimum area" combination you consider best for this project. Use the
ArcGIS help to find background information.
●
The purpose of this aggregation action in the model is that Combines polygons within a specified
distance of each other into new polygons.
●
Aggregation distance: The distance to be satisfied between polygon boundaries for aggregation
to happen. A distance must be specified, and it must be greater than zero. You can choose a
preferred unit; the default is the feature unit.
●
Minimum area: The minimum area for an aggregated polygon to be retained. The default value
is zero, that is, to keep all polygons. You can specify a preferred unit; the default is the feature
unit.
You have erased the aggregated buildings from the preferred building zone around the main and
secondary roads. By means of a visual check, is there more than one polygon created after the erase
tool?
●
All the polygons become pieces.
Open the attribute table of the result after applying the Erase tool twice. How many records are in the
table?
●
Only one
Does the number of polygons correspond with the number of records in the attribute table?
●
Nope.
What does the tool Multipart to Single tool do? and Why do you think this tool is necessary in this model?
●
For some parts, they are seperated but in the project we can make them as a whole part
●
Thus, we reduce the redundant data
Why do you think this selection operation is necessary?
●
Because for the small part, maybe constructors can build something to avoid it. But for the big
parts that are larger than 1 hectare, in the fact, they are difficult to avoid so we may need to do
some changes there.
14/11/2018
Module 10
10.2 Computing Slope areas
A slope of 100% is equal to how many degrees slope?
●
45 degree
What is the raster Source type, Pixel type and Pixel depth of the computed slope raster?
●
Raster Source Type: Generic
●
Pixel Type: Floating point
●
Pixel depth of the computed slope raster: 32-bit
Why does the Slope raster not have a Raster Attribute Table?
●
A raster grid file only holds a single attribute for each cell, to hold more attributes you would
need new rasters for each category.
In which GDB did you save this result?
●
I created a new GDB for test. Afterwards, I will adapt the model to the project so at that
moment I will save it in Component partly and also some results are only for temporarily using,
then I will save them in step results.
What does the tool Region Group compute?
●
For each cell in the output, the identity of the connected region to which that cell belongs is
recorded. A unique number is assigned to each region.
What is the difference between Number of Neighbours to use option Four and Eight in the Region Group
tool?
●
If we only see the results of Region Group, it’s not difficult to find that:
●
Using four pixels has bigger value and more detailed
●
Using Eight pixels has smaller values and less detailed
Results of Region Group: 4/8
Which combination of Number of Neighbours and Zone Grouping Method did you use in your model?
Motivate your answer
●
When you raster zones are long and thin (in other terms the ratio between and area is very big),
the connection between the raster cells to define the zone is defined by the corner cells, for
example steep slopes alongside a dike. In this case it is best to use eight. When the ratio
between perimeter and area slope area is not so big then it is best to use the four option to
define the grouped zones. What a big or small ratio factor is must be decided by the user. It is
necessary to explore where you as a user want to set the ratio threshold between big and small
ratios. This can change per study area.
22/11/2018
Module 10
10.3 Computing "Sink" areas
What does the Flow Direction tool calculate?
Why should the option "Force all edge cells to flow outward" be turned on in this project?
●
If the Force all edge cells to flow outward option is chosen, all cells at the edge of the surface
raster will flow outward from the surface raster. We don’t want the edges cells to influence cells
at the surface.
What do the accumulated values in the Flow Accumulation tool represent?
●
Areas that are easy to be flooded.
Why is the accumulated threshold value needed in this model?
●
50000 means that all 50000 pixels surrounded by this pixels. If the study area is bigger than
that in this case, probably we will increase the number. That’s the function of the threshold
value.
What does the Expand tool do?
●
Expand areas that are easy to be flooded to 10 meters (which also represents 2 pixels because
one pixel is 5 meter here)
Using the wind rose directions as a guideline, what is the main direction of the stream runoff pattern?
Does this coincide with your expectations with the river Rhine as the southern boundary of the project
area?
●
If the Rhine, also called Neder-Rijn in Dutch, where to follow it's natural course, it would flow
between Wageningen en Rhenen in the northerly direction towards Veenendaal and eventually
go to Amersfoort.
●
The Dutch, having a long history in water management, did not like this option and made a dike
between Wageningen and Rhenen to make sure that all water flows in a westerly direction so
that the agricultural development between Wageningen and Rhenen was and still is not
threatened by frequent floods.
Module 11
Why is the Cell assignment type Cell-Center?
●
When the Cell assignment type parameter is set to Cell center option:
Why is the attribute LR_WGT used in the polygon to raster conversion?
●
Because we need LR_WGT to distinguish different suitability
What is the default attribute in the polygon to raster conversion?
●
The first field: ObjectID
Why is the DTM raster dataset used for the options Extent and Cellsize?
●
Then we don’t have to choose one by one for cell size. And also later we need to calculate them
together. Thus, we need to uniform all cell size and extent.
Which cell assignment option is best used in the lightrail application? Explain why you consider this
option to be the best cell assignment option. If necessary adapt your model to this new cell assignment
option you consider best and rerun the model
●
Maximum area method
When the Cell assignment type parameter is set to MAXIMUM_AREA option:
If no priority is specified, and:
Only one feature overlaps the cell, it must overlap by at least 50 percent to be selected.
Multiple features overlap a cell, the largest overlapping area must be greater than the
area in the cell that is not covered by any feature or the cell will be assigned a NoData
value.
Only one feature has the largest area, then it is selected.
More than one feature has the same size area, then the one with the lowest FID is
selected.
If priority is specified:
The feature with the largest positive priority is always selected for conversion
irrespective of the size of the overlapping area.
The feature in question overlaps the cell by less than 50%, and:
The priority is greater than zero, then it is considered.
The priority is equal to zero, then the feature is not considered.
Only one feature has the largest area, then it is selected.
More than one feature has the same largest area, and:
Their priorities are different, then the one with the highest priority is selected.
Their priorities are the same, then the one with the smallest FID is selected.
The feature boundary coincides with a cell boundary, then the boundary rules apply.
●
Maximum combined area method
When the Cell assignment type parameter is set to MAXIMUM_COMBINED_AREA option:
For this description, the combined feature is considered to be a single feature with the
FID equal to the lowest of the combined features and the priority equal to the highest of
the combined features.
If no priority is specified and:
Only one feature overlaps the cell, it must overlap by at least 50 percent to be selected.
Only one feature has the largest area, then it is selected.
More than one feature has the same size area, then the one with the lowest FID is
selected.
If priority is specified:
The feature with the largest positive priority is always selected for conversion
irrespective of the size of the overlapping area.
The feature in question overlaps the cell by less than 50 percent, and:
The priority is greater than zero, then it is considered.
The priority is equal to zero, then the feature is not considered.
Only one feature has the largest area, then it is selected.
More than one feature has the same largest area, and:
Their priorities are different, then the one with the highest priority is selected.
Their priorities are the same, then the one with the smallest FID is selected.
The feature boundary coincides with a cell boundary, then the boundary rules apply.
●
Maximum area I think is the best option for light tram project. Because I will think about within
5m*5m, the largest area can decide which lancover or suitability can represent for this area. In
the previous case, we used Cell Centre. I don’t agree that it is a good idea. It cannot represent
the whole cell when it comes that only a lit bit things in the middle, which makes errors.
Which polygon feature dataset concerning suitability will create the smallest bounding box area extent by
default in the polygon to raster conversion?
The Resample tool also has the option Resampling Technique. Which option do you think is appropriate
to make sure you have the most detail when resampling the suitability raster from 5 to 10 metres?
Motivate your choice.
●
The resample tool has Nearest, Bilinear, Cubic, Majority
●
In this case, I chose Bilinear because compared with the four methods I found out that Bilinear
has the most details. Meanwhile, it won’t influence the suitability values.
24/11/2018
Module 12: Cost Path and Corridors
Will cell values of the "clipped" raster differ from the cell values of the original? Why yes/no?
●
No, I don’t think they are different. Clip is not a tool that changes the pixel value
View your result in ArcMap. Does the result raster have a Value Attribute Table? If so, what are the
attribute names?
●
Yes, it has a attribute table. Names are shown in the figure above.
Do both "Cost Paths" coincide exactly?
●
No, it is shown in the figure below.
Why do you think that both "paths" do not coincide?
●
In general, two paths look kinda similar, but there are several some details are different. I would
think that it’s because the target direction is different for some pixel, which could make
differences.
Where do the biggest differences occur?
Why do you think these differences occur?
●
Compared 5 meters and 10 meters resolution, we can easily find that 5 meters has more details,
which also provide more options when cost path model runs.
Why is it not necessary to change the intermediate model results names?
●
Are there major differences between the lightrail routes when you compute from Source to Target and
Target to Source? If so, explain why these differences took place.
●
Was there a substantial difference in computation time between the computation with the locations
"Environmental Sciences" and "Station Rhenen" and "Bus station Wageningen" and "Station Rhenen"?
HINT: see model reports.Explain why the computation time is the same or not the same.
●
如何将数据里面的几何图形全部分离成独立