Field GISSummer, 2003 Assignment 3GPS ProjectGPS Class Project:Trimble Tutorial File (600+ pages!!!)Pathfinder WalkthruPart 1. The objective of this exercise is to collect data for a comparison of methods using different GPS observations. The football practice area west of the library has a "benchmark" in each corner (called A, B, C, D). Benchmark A is a punch-mark on the east side of the rim to a manhole cover at the SE corner of the practice field. B is the northerly most bolt on top of a fire hydrant at the SW corner, C is the center screw on an small access cover in the NW corner, and D is a punch-mark on the south side of the rim to a manhole cover at the NE corner. You are to collect and process a series of GPS data and compare GPS distances between benchmarks with measured distances between benchmarks (this area has been surveyed using a Total Station). You are also to compare results from the different GPS methods. You will work together in groups, but write-ups will be each person's responsibility. The DGPS and position data should be collected at 5 second intervals. All GPS positions should be in the WGS84 (NAD83) datum. Use State Plane Custom (goofy) coordinates for all final positions so they plot on your basemap (DOQ). For the NE corner (D) benchmark the following data will be collected.
This data will be analyzed as part of the final writeup, and compared with the Field Methods Class results. Transfer the data to PC format in the Geology computer lab, differentially correct as appropriate, and bring the data into Arcview. Average the data where apropriate. Print a map clearly showing the different data sets, use multiple maps if necessary. You will also determine your pace using a tape measure, include this result in your report. Also discuss line width relationship to scale of map. For example, how wide is a 0.1 point line at 1:24,000? 1:100,000? Note: A point is 1/72 of an inch. So 72 point font results in one inch high letters! Discuss sources of error in using GPS in your report. Discuss applications for which you would use different collection methods. Part 2. Collect data with garmins and trimbles at the Duniway track. Note which track number you are on (8 tracks?). Plot differentially corrected data, non-corrected data and garmin data to see how they are related. Use data collected by your classmates to fill in the database of observations. How would you collect the data differently next time? How would planning software help? Part 3 Use the planning software to determine the best time to avoid obstacles at Duniway, also for the Marquam trail. Create a data dictionary for collecting points, lines and polygons at these 2 sites, download the data dictionary to a Trimble and go collect the data! Plot this data on your basemaps from assignment 2. Which basemaps work best? Why? Questions? Comments? Contact Percyd@pdx.edu
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