Introduction:
The purpose of this lab was to familiarize ourselves with the general process of collecting data with a GPS (create a personal geodatabase, collect data in that geodatabase, then making a map with the data).
Methods:
For data collection, a Juno 3B GPS unit was used. Prior to collection, a geodatabase was created in ArcCatalogue. In ArcMap: points, lines, and polygon feature classes were created. A raster image and campus buildings shapefile (shown as brown polygons in Figure 1) were also brought into ArcMap. Next the data was exported as an apo. file to the Juno unit and ready for data collection.
Results:
As Figure 1. shows the data collected wasn't very accurate. Although most of the time my PDOP value was under 2.0, my data still wasn't very accurate. The Juno unit should have given me 2-5m accuracy. However, there were many multi-path errors in the form of buildings and trees. The main source of error probably came from the atmosphere in the form of overcast skies. There was a mixture of rain and snow, so I imagine the error from the Troposphere was higher than usual. In conclusion I wouldn't recommend mapping out sidewalks with a GPS, digitizing would probably work better.
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| Figure 1. Collecting points, lines, and polygons on the lower campus mall at UW- Eau Claire. |
I had two hiccups during this exercise. The first came when my project file wasn't loading on the Juno unit. I think the issue revolved around my data dictionary. I ended up checking out a new unit and going through the creation of my dictionary again and re-deployed the data successfully to my new Juno unit.
The second problem came when trying to "check-in" the data to the mxd. would show the data collected. Apparently when trying to remove some of the clutter in my folder I deleted the old data for the first Juno unit. In the process I deleted the geodatabase for my points, lines, and polygons. To fix this I created a new geodatabase and brought the data back into that geodatabase.
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