Yellowstone GPS On the Internet

Corey Cortez
Spatial Data and Visualization Center
July 29, 1998

Abstract

Using maps these days just doesn't seem to cut it for most people. People want to know exactly where they are, where their house is, where their dogs bury that bone or where their daughter or son went with your brand new car. Using the Global Positioning System (GPS), we can accurately map the location of where that bone went. For my project this summer, I applied GPS technology to collect scientific information. While in Yellowstone National Park, I used the GPS equipment to gather digital locations of radon sites, along with thermal sites, paths, walkways, buildings, and fences. The mapping of these sites were done so the scientific information could be served on the Internet for other scientists, researchers, and the general public to access.

Introduction

During the seven week Student Research Apprentice Program (SRAP), I worked at the Spatial Data and Visualization Center (SDVC). I worked with one SRAP student (Maricella Sanchez) and a University of Wyoming (UW) undergraduate Rose Gonzales. For the first week, we learned about using Trimble's GPS Pathfinder Pro XR. We also prepared for our field work in Yellowstone National Park (YNP). In late June 1998, we spent six days gathering digital coordinates for radon sites as well as mapping out paths, buildings and other objects. In early July 1998, we took the information from the GPS units and downloaded the information to the computer (using Trimble's Pathfinder Office 2.01). Now with our digital points on the computer, we began to look over the data, and differentially correct them because of selective availability. We exported the differentially corrected data into Geographic Information Systems (GIS) software (ArcView 3.0). We overlaid the GPS data on digital raster maps and digital orthophotos. Then we got the data ready for the Internet Map Sever (IMS), where we will display the data for public access.

Methods and Materials

After the field work in YNP we need to get the data on the computer so, we took the information from the GPS units and downloaded the data to the computer using software called Trimble's Pathfinder Office 2.01. Now with our digital points on the computer we began to look at them. The points' accuracy rate is +/- 100 meters without differential correction, so I differentially corrected the files from The Montana Department of Transportation base station in Helena, MT (http://www.mdt.mt.gov/isb/gps.htm). Now with the files corrected the accuracy rate is +/- 10 meters. It is because of selective availability that I had to differentially correct the data. Selective availability is the largest source of error in GPS, generated on purpose by the military to reduce GPS position accuracy. Without correcting the data, our GPS points would not overlay with the DRGs, or the digital orthophotos. Now with the corrected data I could delete unwanted points or incorrect points.

Next, I begin to export them into ArcView 3.0. In ArcView 3.0 desktop-mapping software, I add DRGs and digital orthophotos for overlay with the GPS points. I got the DRGs on the Internet from the Wyoming Spatial Data Clearinghouse (http://wgiac.state.wy.us/wsdc). The digital orthophotos I imported into ArcView 3.0 from CD-ROMs available from SDVC. Because the digital maps and data are not in the same datum, I had to change the datum of the GPS data. The DRGs are in datum NAD 1927. The digital orthophotos are in datum NAD 1983, and the data from the GPS is in datum WGS 1984. Therefore, I had to transform the data to NAD 1927 and NAD 1983. I did this using Trimble's Pathfinder Office 2.01. Soon afterward, I exported the corrected files in the correct datum to ArcView 3.0. I ended up with two separate ArcView 3.0 files in one folder with the GPS data in datum NAD 1983 for the digital orthophotos, and one folder with the GPS data datum NAD 1927 for the DRG's. Now with the information correctly exported, I added the DRGs and digital orthophotos so we could see where are sites were positioned on the digital maps.

From ArcView 3.0, I began to clip the DRG's and digital orthophotos. I made these clippings from the DRGs and digital orthophotos, along with legends, north arrows, and the scale of every map using a program called Image Magic. I clipped 28 DRG's, 18 digital orthophotos, 28 scales, 3 legends and 1 north arrow (Appendix C). To make sure that all the radon sites were clipped and made into an image. I took the coordinates of the radon sites that we didn't GPS from the maps and entered them into ArcView 3.0.

When all the images were finished from the clipping process, I designed the web page for displaying the results. I use HyperText Markup Language (HTML) to design this page. In addition to the clipped images, the web page also has digital pictures of the field work from 1993 and 1998.

Results

With the GPS unit 75 out of the 95 radon sites were mapped. I took the coordinates of the radon sites that we didn't GPS from the maps and entered them into ArcView 3.0. Position dilution of precision (PDOP) is the best indicator of accuracy when using the GPS units. Our PDOP on average was 4.0 during the days that we were in YNP. The charts in Appendix B (example) were taken from the Trimble web site http://www.trimble.com. The dates are from June 23, 1998 to June 27, 1998, that time duration is 12 hours.

On the IMS the radon information is not yet complete, there is still lot of work to be done to make all the information complete.

Conclusion

Now with modern technology we can accurately find our exact coordinate using GPS. Anybody can use it, but mainly it's used in ships, airplanes, for land surveyors, science reasons and for recreational uses. It has helped me to accuracy map the radon sites. It has made it easier for anybody to relocate those sites I mapped, in the future. But if you are going to use GPS to find your way around a forest or desert, remember always bring an extra set of batteries and don't rely on the GPS totally. A good map and a trusty compass are always handy to carry around in your pack just in case.

Future Plans

I graduate in May 1999 from Laramie Senior High, Laramie Wyoming. When I graduate, I plan to spend my summer filled with lots of relaxation. For the fall of 1999, I plan to attend a college in the New England area and pursue an MBA in Business Management or Computer Information Systems. However, I still have another year of school ahead of me to decide my future in the world.

Acknowledgements

I would like to thank the Spatial Data and Visualization Center (SDVC) staff for helping me learn and understand new tools that could help me later on in life. Working with the GPS's has been a great experience for me. I want to thank the following people in the SDVC office. Margo Herdendorf for changing the projections on the digital orthophotos and helping me get things done. Phil Polzer for helping me get that data on the web. Scott Parrill for helping me with those fun times when the computer didn't do what I wanted it to. Al Deiss for scanning the YNP pictures onto the computer. Jim Ward for hooking us up Power Point and other computer problems I ran into. Nick Visser for reading over this report and showing me first hand the cool 3D maps. Steve Gloss the director of SDVC for supporting the SRAP program. And to Cheryl Jaworowski, a person that can tell you everything there is to know about Wyoming Geology and more, "it's been an experience". I'd like to thank all the people in YNP that helped us. The park rangers for letting us use their showers. The staff of the Bridge Bay Campground for letting us use their power supply. To the Research office who gave us permission to work in the park by granting our permit. To the GIS office in Yellowstone http://www.nps.gov/yell/gis, for letting us use their computers having us come do research in YNP. And to the NSF-EPSCoR program for funding our field work in YNP. To Rose Gonzales thanks for helping me out. A special thanks to Maricella Sanchez my partner for telling me all the days gossips, so I was always informed about what was going on and for being a fun sidekick to work with this summer. Thank-you everybody.

Appendix A

Log while at Yellowstone National Park

I took this log while we did our field work in YNP. It starts June 22, 1998 and ends when we returned to Laramie, Wyoming June 29, 1998.

Monday 22: Left Laramie in the morning. Stopped in Riverton to eat lunch and get groceries. Stopped in Dubois at Motel 8 for the night.

Tuesday 23: Left Dubois to YNP (we entered through the south entrance). Set up camp at Bridge Bay Campground. Then headed up to Mammoth. At Mammoth, we got the permit. From Mammoth, we went to Boiling River. From Boiling River, we made the data dictionary then headed back to camp.

Wednesday 24: left camp for Boiling River. Mapped the path to the springs and radon sites. Then headed to the town of Mammoth where we mapped more radon sites and around the Mammoth area quad.

Thursday 25: Went to Norris and West Thumb quads to map out radon sites with GPS rained most of the day.

Friday 26: GPS Mary Bay Point and Steamboat Point. Ate lunches at Lake. Went back up to Mammoth/Norris (snowed on way up to mammoth)

Saturday 27: woke up with snow on the ground, the rest of the day was bright and sunny. Stopped to eat lunch watch Old Faithful. GPS Lone Star geyser area and Firehole River. We walked about 8 miles altogether today.

Sunday 28: Last day in Yellowstone. Went to Mammoth to differently correct GPS data. The Internet was down so we decided to wait until we got back to Laramie to differently correct the GPS data. Left the park at about 4:30pm. Headed to Shoeshine National Forest were we stayed the night at a Cabin in Sunlight Basin.

Monday 29: Left Sunlight Basin in mid morning and headed home. We stopped at Shoshoni to eat lunch. Got back in Laramie early Monday evening. Page 5 of 11