Friday, October 8, 2010

Random Feature Selection

I met with a gentleman today who needed to select random streets in Wilmington in order to do a field survey of urban forestry there. Here are the steps we took to do so:

-Use Excel and the RANDBETWEEN function to generate random numbers in a range = total number of features (in this case, streets in Wilmington). Drag this equation down a column = number of features in sample. Once this has been done, save/export (I usually like to use DBF for ArcGIS)


Bottom is the smallest integer RANDBETWEEN will return.

Top is the largest integer RANDBETWEEN will return.

- with data added to ArcGIS, use "Frequency" tool to check that no duplicate values were generated

- do a regular one to one join, dropping out all values that don't match. The result will be a random set of features -- in this case, street segments.

Thursday, October 7, 2010

View KML Source from MyMaps

Google MyMaps allows you to export KML by using the "Export to Google Earth" feature. If you copy/paste the URL that this button links to you get a KML, but it is a network reference to the actual KML. If you copy/paste the URL referenced in this KML in your browser, you'll get a warning "{errorText:"Unable to contact server."}". To get past this warning, you must decode the encoded URL reference. That means getting rid of all the "amp;" strings.

For example, change:


and you'll get the actual kml. You do not need to do this within any script or program, since those tend to encode URLs anyway. However, it is very useful for debugging issues with KML.

Friday, October 1, 2010

Geoserver Labeling, Font Changes

Wierd Geoserver Behavior (bug): font changed from Arial to some kind of serif font for no apparent reason. I fixed this by clearing all caches and restarting the Geoserver service. I'm still not sure what caused the issue.

Animal Movement and Home Range Options for ArcGIS

The Animal Movement Extension was written in Avenue, and development stopped many years ago. Therefore, Animal Movement Extension is not available for ArcGIS 9.x or 10.

There are a couple of options if you'd like to move forward with ArcGIS

  • A lot of people using Animal Movement extension migrated to Hawths Tools, to be able to use ArcGIS. Hawths tools offered many of the functions in Animal Movement, though Hawths tools is also now a discontinued project, and will not work with newer versions of ArcGIS (9.2 was the last version it worked with).
  • Hawths tools has been been merged into the Geospatial Modeling Environment, which works with ArcGIS 10. You can download this and find more info at:
  • Home Range Tools for ArcGIS works on ArcGIS 9.x, and is available at
  • There is a lot of work going on with Agent Based modeling right now. I met with an agent based modeling working group at the ESRI conference. They've developed an extension for ArcGIS based on repast called Agent Analyst: . I didn't hear about any scenarios involving wildlife movement, buy there is a book coming out, and I would assume those scenarios might be discussed. I'll keep my ear to the ground on this one
  • There are also contributed and native tools and scripts that could be used to perform many of these functions if strung together in the right order
Other Resources