Bathymetric Mapping of
Dells Mill Pond
Tools of the Trade
This is the Trimble GeoExplorer. It
allows the user to set data categories
and use them to store data to be transferred
to the computer for use in the map.
This is a Humminbird depth locator
this is used with the GPS to acquire
water depths, which are stored in the
GPS and later put in the map.
More Tools
Moving about the lake is made easier by using an
electric trolling motor like this one. They are easy
to use, and starting and stopping is very convenient.
I used a boat like this one. A flat
bottom for stability and it does not
need a lot of water to float in. The
seats were handy for setting the GPS
and depth sounder on.
GPS
The GPS is a very unique and useful tool. It uses satellites in space to
locate a way point on earth. These way points are then used to make the
map. There are several different steps that must be taken to get the GPS
set up before use.
1. System Setup: After the GPS has been stored for a while it
needs to find the satellites again.
2. Enter Data Dictionary: This is a program that the GPS uses, it
allows the user to select the type of data to be saved, whether it is, point,
line, numbers, or one of the many that are available.
Data Dictionary
This is an example of a
Data Dictionary. The
features are on the left
side, I have entered
Depths. On the right
are the Attributes, for
this I have entered the
depths: 2,4,6. When I
crossed a depth change
I would enter it in the
correct attribute.
Getting the Shape
The first step to the mapping process is to make an
outline of the pond. I used the GPS and the boat to
follow the shoreline. Once that was completed I went
to the computer and saved the data for later use, with
Pathfinder Office.
Collecting Data
Getting out on the water and actually getting the information that is
needed was the fun part of this project. The best way that I found was
to go in a zig-zag pattern. Every time a depth change was crossed its
way point was entered into the GPS for later use. Getting good data is
important for having an accurate map. I worked on both ends of the pond,
while doing this I found that the north end had more irregularities than
the south end. Because of this I had to spend more time on the north end
getting very accurate information. When I got to the south end I was able
to go over it quickly because it didn’t change very much.
Information Processing
The first step in getting
the data from the GPS to
the computer is to select
the data transfer option.
This will allow you to get
the information and start
making the map.
Information Processing 2
This is the Data
Transfer option. In this
step the files from the
GPS that are to be
transferred are selected,
also the place where it is
to be saved is selected.
This process transfers
raw data from the GPS to
the computer. Because
of government scrambling
the information must be corrected. The UFCORS is a web site that
provides the necessary information, for correcting.
Correcting Files
This is the web
page that is used to
correct the GPS
Data. Certain
numbers and other
information must
be entered into the
form, then the file
for correcting the
files will be sent.
Get Unzipped
Because the files are zip files I had
to unzip them. This was easy enough,
I used the program WinZip. The files
were changed to a format that could
be used by the computer. Now I was
able to correct the data to be very
accurate.
Formatting
Using Pathfinder and
the differential
correction option along
with the correction files
from the internet, all
information was
corrected. This moves
all data points to the
correct position, doing
this makes the map very
accurate.
Starting the Map
Here is a sample of a map.
The outline of the shore and some
of the data have been added to
the view the next step will be to
add the rest of the depths.
Then every depth category will
be connected.
Connect the Dots
Here is the map with
some of the raw data
from the GPS on the
shoreline map of the
pond. There are three
depths with different
colors. Connecting
the dots at each color
will give depth
contours for each
value.
Getting Close
Here is the map before
the final touch-up stage
some of the lines run
together, and some don’t
go anywhere. These
are all things that will
be fixed before the
final stage.
Wrapping it up
Here is the final map
the keys have been
inserted, the depths
labeled, and the whole
thing has been cleaned
up. Now all that is
left is to publish it,
and get it out to the
public.
Useful Tools
Howie’s Funware- This was used to take pictures of the computer.
ArcView- This program was used in the map making process.
Pathfinder- Another mapping program.
Power Point- Used to make this presentation.