Thursday, March 26, 2015

Vector Analysis: How to Find a Good Campsite

Another fantastic week! Can't believe I am so close to finishing GIS4043. Not that I am happy to be done, but I am happy I made it this far.  This week, we continued our examination of Spatial Analysis of Vector and Raster Data.  The specific objectives were:

- Define and use two of the most common modeling tools in ArcGIS: buffer and overlay
- Use the Dissolve tool to merge overlapping borders of buffer zones
- Create a script in ArcPy to run the buffer tool
- Analyze vector data using spatial queries
- Create a simple buffer around vector features
- Create a variable distance buffer around polygon features
- Identify the 6 overlay operations available and recall when to use each
- Use the overlay modeling tool to combine or exclude multiple features
- Distinguish between multipart and singlepart layers and convert between the two
- Quantify and explain the difference between results derived from buffer and overlay operations

Wow! That seems like a lot to do and believe me, it was. The main objective was to become familiar with Analysis Tools and ArcPython. The ArcToolBox is full of great items to use, though some are difficult or tedious to find when you've never used them before. As was my case. I learned to use the Search Icon often. This helped me tremendously and probably saved me countless hours of searching for the right tool. Kind of how I am in the garage.  Anyway, I used the Buffer tool to create zones (buffers) around Lakes, Rivers and Roads to ultimately find a suitable campsite somewhere in The DeSoto National Forest.  The criteria for the campsite was:

- Within 300 meters of a Road
- Within 150 meters of a Lake
- Within 500 meters of a River and
- Outside the Conservation areas

Additionally, I learned how to use the Multipart to Singlepart tool-- this one was definitely hard to find and I couldn't have done that without the Search Icon.

As for the ArcPython, it's a good thing I am familiar with Python from my website development study of Drupal. The most challenging part for me was to ensure I had the code syntax correct. Sure enough, I forgot the "close parenthesis" on one of my scripts and it just blew up in my face.  But, I did catch my omission and the code ran smoothly afterward.

Below is my final map.

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