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Goal
Background: The goal of this assignment was to create a map based on Global Positioning data gathered through the use of a Trimble Juno SB handheld unit.
Purpose: The purpose of the assignment was to gain a better understanding of how to acquire data from the field and how to analyze that data for use in maps and potentially for other products as well.
Methods
Step One: In order to initiate the process of data acquisition through the use of a Trimble Juno SB handheld unit, a geodatabase was created through ArcCatalog. Feature classes were created in the form of points, lines, and polygons and a field named "Type" was assigned to each created feature class in order to assign attributes to the feature classes in the field. The geodatabase was given the coordinate system "NAD_1983_HARN_Wisconsin_TM meters". A blank map was opened in ArcMap and the features were added to the map, along with a "CampusImage" raster file. Different symbologies were assigned in order to make the features more aesthetically pleasing.
Step Two: The map containing the feature classes that was just created then was uploaded to the Trimble Juno SB unit for deployment into the field. Using ArcMap, the extension to allow data management through ArcPad was activated. This menu allows for the uploading and downloading of data acquired from the Trimble Juno units that use the ArcPad program. The correct files were selected and they were uploaded onto the Juno units.
Step Three: In the field, various methods were used in order to demonstrate the various ways to collect data. In order to commence data acquisition, ArcPad was launched through the Trimble Juno, the correct map was opened, and the correct feature was selected for acquisition. Six polygons were recorded in this exercise, three of which were recorded using point averaging, and three of which were recorded using point streaming and each polygon's "Type" was specified in the field. Point averaging is a process where an initial point was recorded averaging three point in the surrounding area and mathematically placing one point, depending on the average of those three other points. This resulted in a series of connected, straight lines. Point streaming is a process of continuous data acquisition through recording data points every few seconds, resulting in a non-linear line. Issues can arise with both methods if the Position Dilution of Precision (PDOP) value is too high, increasing the likelihood that that the location of the data will be off. In the field on the day of acquisition, the PDOP value was significantly low, usually reading 1.4. A lower PDOP, especially anything below a 4.0 will provide significantly accurate data acquisition.
Six point values were also acquired. In this exercise, three lamps and three trees were recorded and their "Type" was specified in order to gain a better understanding of the process.
A line was also recorded in order to gain a better understanding of how to acquire line data through ArcPad. Instead of only taking a point average line in this portion of the exercise, I also retraced my steps using a point streaming method. The various methods can be seen, labeled, on the map above. Not much difference was noticed, other than swaying in my line that I walked. As noted before, the PDOP value was significantly low on this day, so the point streaming values seemed to be very accurate.
Step Four: After recording the data in the field, it was transferred back onto the computers used before to construct a map in ArcMap. This process involved reconnecting the Trimble Juno units to a computer, navigating to the correct folder, and copying the data into our class folders. Following this, the ArcPad Data Manager was used to check in the data, using the map that was created during the first part of the exercise. It should be noted that I encountered some initial errors here. When attempting to transfer the data back, an error message was received that told me that I was unable to check in the data because the map was not editable. After some troubleshooting, it was found out that at some point I had attempted to organize my lab folder and the original file was moved to within another file. This severed the connection between the initial geodatabase and the current data. The geodatabase was moved back to where it had been and the data transferred in the way it was supposed to.
Step Five: A map was constructed with all the recorded data and the necessary components for a distinguishable, cartographically and aesthetically pleasing map.
Results
Through this exercise, I was able to gain a much better understanding of multiple software components. I gained a better understanding of the construction of geodatabases and building feature classes through ArcCatalog. I learned how to transfer data to and from Trimble Juno SB units. I learned how to properly record data while in the field for multiple feature classes, using multiple methods. Finally, I learned some various methods to troubleshoot on the fly. For example, at the beginning of my data collection I was unable to get a satellite fix. A simple reboot of the system was able to rectify this issue. As stated previously, I had issues transferring my data back from the Juno units. I was able to rectify this by remapping my geodatabase back to its original location.
Data Collection by Zach Hilgendorf on October 16, 2013
NAIP 201X
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