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TAITA TAVETA UNIVERSITY
Caleb Y. Mutie
TU01-SG214-0869/2019
SIG 2312
Spatial and Network Analysis
Assignment
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NETWORK ANALYSIS
Explain various sources of x, y, z data in spatial analysis
Spatial analysis or spatial statistics includes any of the formal techniques which studies
entities using their topological, geometric, or geographic properties. Spatial analysis includes a
variety of techniques, many still in their early development, using different analytic approaches
and applied in fields as diverse as astronomy, with its studies of the placement of galaxies in
the cosmos, to chip fabrication engineering, with its use of "place and route" algorithms to build
complex wiring structures. In a more restricted sense, spatial analysis is the technique applied to
structures at the human scale, most notably in the analysis of geographic data or transcriptomics
data. According to ESRI, spatial analysis includes examining the locations, attributes, and
relationships of features in spatial data through overlay and other analytical techniques in order
to address a question or gain useful knowledge. In conjuction to that, "XYZ" data can be entered
into the Utilities datasheet to represent X and Y location coordinates and a measured "Z" value
of some kind, such as elevations or geochemistry. This basic data layout can be run through Map
to create a simple point map or line/color-filled contour map.
Uncertainty in the raster data structure: The raster structure partitions space into square
cells of equal size (also called pixels). Spatial objects x, y, and z emerge from cell classification,
in which Cell A1 is classified as x, Cell A2 as y, Cell A3 as z, and so on, until all cells are
evaluated. A spatial object x can be defined as a set of contiguous cells classified as x.
Commonly, a cell is not purely one thing or another, but might contain some x, some y, and
maybe a bit of z within its area. These impure cells are termed "mixels." Because a cell can hold
only one value, a mixel must be classified as if it were all one thing or another. Therefore, the
raster structure may distort the shape of spatial objects.
Location Data Sources and Types of Location Data
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Global Positioning System (GPS) A GPS provides latitude-longitude coordinates
gathered by the hardware on a device which communicates with a satellite such as a car
navigating system, a mobile phone or a fitness tracker.
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Software Development Kit (SDK)
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Bidstream
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Location data lets someone use a smartphone or GPS device to accurately navigate, for
example. Moreover, location data can be used in a variety of contexts, such as manufacturing
and industrial settings to manage risk and improve safety and security.
Global Positioning System:
This tool provides the three-dimensional cartesian coordinates in which they are called EarthCentered-Earth-Fixed coordinates. It is a right-handed orthogonal system that rotates with and is
attached to the Earth, which is why it is called Earth Fixed. GPS (global positioning system)
coordinates are usually expressed as the combination of latitude and longitude. Latitude is a
measure of degrees of distance from the equator, which is 0 degrees. The north and south poles
are at 90 degrees in either direction.
In order to get the XYZ data from GPS, conversion of latitude and longitude to XYZ coordinates
is done. This value is the scientifically derived value for radius of the earth. Calculate latitude
and longitude using the formula: latitude = asin (z/R) and longitude = atan2 (y,x). In this
formula, we have the values of x, y, z and R from step 2.
Photogrammetry:
The XYZ data can be achieved when photogrammetry is carried on. In aerial photogrammetry,
data are captured from an aircraft with a camera mounted vertically or obliquely towards the
earth surface. Its achieved in terms of image space coordinates and ground space coordinates
during the time of data capture. There is also collinearity condition and equations whereby when
achieved on both photos in a stereopair then the ground X,Y,Z can be computed from x and y
within the image coordinate system on both photos. The equations can be derived using GCPs
and tie points
Data from Images
We can achieve three-dimensional data from images. This can be achieved from the projection of
light patterns into a scene. The light patterns are projected onto the objects which lie in the field
of view of the camera. The distance of an object to the camera or the location of an object in
space can be determined through analyzing the observed light patterns in the images. The active
manipulation of the scene by using light patterns simplifies the 3D reconstruction task
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enormously.
Data from Bidstream:
This involves implementation of Global Navigation Satellite System technique in civil aviation
for recovery of aircraft position using precise point positioning method in kinematic mode.
Design/methodology/approach. The aircraft coordinates of Cessna 172 plane in XYZ geocentric
frame were obtained.
Software Development Kit.
In the TobiiPro SDK, there are different coordinate systems. In order to be able to correctly
interpret coordinates delivered from the SDK it is important that you understand the difference
between these coordinate systems.
In the description of the coordinate systems, the word user denotes the person whose eyes are
being tracked by the eye tracker.
Active Display Coordinate System (ADCS)
All gaze data are mapped into a 2D coordinate system aligned with the Active Display Area.
When using an eye tracker with a monitor, the Active Display Area is the display area excluding
the monitor frame. For eye trackers used without a monitor, the Active Display Area is the area
used to show the calibration points when doing the calibration of the eye tracker to the user’s
eyes.
The origin of the Active Display Coordinate System is the upper left corner of the Active
Display Area. The point (0, 0) denotes the upper left corner and (1, 1) the lower right corner of it.
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User Coordinate System (UCS)
Most data, available from screen based Eye Trackers from Tobii, that describe 3D space
coordinates are given in the so-called User Coordinate System or UCS for short. The UCS is a
millimeter-based system with its origin at the center of the frontal surface of the eye tracker.
The coordinate axes are oriented as follows: the x-axis points horizontally towards the user’s
right, the y-axis points vertically towards the user’s up and the z-axis points towards the user,
perpendicular to the front surface of the eye tracker.
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Other sources of spatial data in spatial analysis
Discovering Geographic Data.
Exploring GIS Data.
1. Discovering geographic data.
Most data and measurements can be associated with locations and, therefore, can be placed on
the map. Using spatial data, you know both what is present and where it is. The real world can be
represented as discrete data, stored by its exact geographic location (called “feature data”), or
continuous data represented by regular grids (called “raster data”). Of course, the nature of what
you’re analyzing influences how it is best represented. The natural environment (elevation,
temperature, precipitation) is often represented using raster grids, whereas the built environment
(roads, buildings) and administrative data (countries, census areas) tends to be represented as
vector data. Further information that describes what is at each location can be attached; this
information is often referred to as “attributes.” Thus, as the information in the geographic data
discovered can contain attribute having X,Y & Z data .
2. Exploring GIS data
Spatial data have traditionally been generated through mapping data in the field, but
recent technological developments have widened the possible avenues for creating data
for use in GIS. The most common method of collecting spatial data is the use of global
positioning system (GPS) receivers. Thus, as stated earlier GPS provides XY and Z hence
being a source of data in spatial analysis.