Term Project Paper
CE 394K - GIS in Water Resources, Fall 2002
University of Texas at Austin
Topographic Analysis of City of Austin Parks (click to go to trails)
by Brian Carrico
Outline
- Obtaining the shapefiles and topographic maps
- Getting DEM data from the USGS Seamless Data Distribution System
- Incorporating the trail maps into ArcMap
The primary goal of this project was to use GIS tools to create maps for topographic analysis of some of Austin's recreational cycling areas. Moreover, the maps were integrated into HTML format to make a functional website that would allow users to click on the riding are of their choice in order to obtain a description of the area, maps of the trail, and elevation profiles associated with each trail. This would allow users on the web to benefit from the GIS analysis of the trails in order to select where to ride. For this project, three of the most popular mountain bike trails in Austin were chosen: the Barton Creek Greenbelt trail in Zilker Park, the Emma Long (City Park) Motocross trail, and the Walnut Creek Park trail. This project report focuses on the steps associated with obtaining the GIS maps, the Digital Elevation Maps (DEMs), integration of hand drawn trail maps into ArcMap, and the synthesis of it all into the HTML format to create the trail website.
Obtaining the shapefiles and topographic maps
All of the two dimensional maps used for this project came from the City of Austin's GIS Data Sets website. To start, the Austin base map, street centerlines, rivers, lakes, and City of Austin parks layers were loaded into a personal geodatabase created in ArcCatalog. These maps were used as the basis for the map of Austin usedon the website main page and they were also valuable in orienting the trails that were later added. The next step in the data collection for this project was to obtain the topographic maps for each park area. The topographic maps were also obtained from the City of Austin's GIS Data Sets website. Since they are such large files, the website has directions for downloading the contour files based on USGS 7.5 minute Quarter Quads of the city.
Getting DEM data from the USGS Seamless Data Distribution System
The DEMs used for this project were obtained using the USGS Seamless Data Distribution System. This system is an exciting new development in obtaining elevation data for use in GIS applications. In order to obtain the data sets, you first click on the "View and Order Data Sets" icon from the USGS Seamless Data Distribution System homepage. That icon then takes you to a map of the entire United States, where you can use the "Zoom In" tool to focus on your specific region of interest. You can then manipulate the layers located on the right side of the screen to orient yourself and obtain a map of the area you are interested in. Mine looked like this:
After finding the area you want, you can download maps for the region you are interested in by clicking on one of the "Download" tools, and selecting the area that you want to download data for. If your selection can be downloaded for free, the selected area will be highlighted in green, and then all you have to do is follow the ordering instructions to get your data! I ordered DEM data from the National Elevation Dataset (NED) for the area corresponding to each park and then added those as layers to my ArcMap document that was created with the aforementioned layers.
Incorporating the trail maps into ArcMap
The last step in the data collection for this project was obtaining the trail maps themselves. I obtained the trail maps for each riding area from Discovery Cycles in Austin, TX where I have worked as a bicycle mechanic for the last three years. These maps were created by trail riders and, like all bicycle trail maps, are not exact representations of the trail. One reason for this is that the precise layout of the trails tends to change with erosion, fallen trees, and other factors. That said, I traced the trail maps into the ArcMap document "by hand" using the 3-D analyst line interpolation tool, which will be discussed further in this report. I used both the trail maps and my own knowledge of the trails to fill in any gaps when tracing the trails into ArcMap, and I feel that the combination of the trail maps available and my own experience in riding these trails regularly resulted in a highly representative, although not entirely accurate, map of each trail.
To begin with, I created a personal geodatabase in ArcCatalog and loaded the Austin basemap file, austin_base.shp. Next, the other layers were added to the geodatabase to create the Austin map that includes the lakes, parks, and major arterials.
Next, the DEMs and topographic maps were added to the ArcMap document based on the methods described in the Data Collection portion of this report. After all of the layers needed for the analysis were loaded into the map, I played with the display of the layers and zoomed in on each of the parks in order to add the trail maps.
To add the trail maps, I zoomed in on the ArcMap and then made the trace of the trail map "by hand" using the 3-D analyst. Originally, I investigated adding a scanned version of the map into ArcMap as a layer. Upon closer inspection though, both the trails and the surrounding roads on the maps were originally drawn by hand, so transferring them into the Arcmap document would not necessarily make the trail maps any more accurate. Instead, I created new three dimensional lines using the Interpolate Line tool in the 3-D analyst based on looking at the trail maps, comparing them with other layers contained in the map, and using my own knowledge of the trails to try to orient them more accurately. This process was used for both the City Park and Barton Creek Greenbelt trails, but for the Walnut Creek trail, trail maps are not yet available. Since the Walnut Creek Park trails are a new system of trails and no trail maps are available yet, I created a "hypothetical trail" that traversed over the major elevation changes to give an idea of the potential of the Walnut Creek trail system in terms of elevation changes.
Finally, after adding the line representing the trail, the profile graph was created for the trail by using the Create Profile Graph tool in the 3-D analyst toolbar. Since ArcMap offers very little manipulation of the graphs, he profile graphs for each trail were copied to the Windows Paint program to change the size and look of the graphs.
Incorporating the ArcMap documents into HTML is actually an easy process that can be applied to any GIS map, and provides a valuable tool for internet users who may not have access to GIS otherwise. First of all, you can just create a web page in a HTML editor (Microsoft FrontPage was used for this project) as the basis for the maps to be displayed. I found the best way to display the maps was to copy them by using Ctrl + PrintScreen while ArcMap is open to copy it onto the Microsoft Office clipboard and then pasting the map into Microsoft Paint or any other picture editing software. This method has a few advantages:
1. Microsoft Paint and other picture editors allow you to do basic manipulations of the map to make it more presentable in HTML
2. Picture editors allow you to convert your map to a much smaller file than if you use the layout view from ArcMap, shortening download times.
After putting my overview map of Austin into the HTML editor, I made a clickable map that would allow users to click on their trail of interest and be sent to a web page specifically for that trail. I did this for my project by creating hotspots on the picture using the Image toolbar in FrontPage, this is a basic function that can be executed in any HTML editor program. I went on to create a new page for each of the trails, linked those pages to their respective hotspots, and incorporated four types of maps for each trail;
1. The scanned in trail map obtained from Discovery Cycle
2. The topographic map of the park with 2-foot contours
3. The elevation profile graph for the trail obtained from the 3-D analyst tool in ArcMap
4. The DEM for each trail with the trail overlaid.
Whenever I ran into problems creating my website for this project, I used the University of Wisconsin - Eau Claire FrontPage help website, which was a big help when I ran into little snags along the way.
- For me, this project was an interesting opportunity to use the skills I learned in Dr. Maidment's GIS class to create a useful tool for web users to benefit from ArcGIS's capabilities.
- Along the way, I learned how to use the USGS Seamless Data Distribution System, which is a great way to obtain elevation data for anywhere in the United States.
- The 3-D Analyst tool in ArcMap can be used for showing elevation data in an interesting manner.
- Incorporating maps created in ArcGIS into HTML is an easy way to display GIS data to users who do not have access to GIS software.
- Future GIS analysis of mountain bike trails could be greatly enhanced by precise plotting of points along the trail using a GPS.
Austin map layers: ftp://issweb.ci.austin.tx.us/pub/coa_gis.html
Deigitial Elevation Map layers: http://seamless.usgs.gov
Microsoft Frontpage Resources: http://www.uwec.edu/help/fpage00.htm
Trail Descriptions: http://www.austinridgeriders.com