Friday, October 9, 2015

New tool - Generate points around points aka generate background points or available points

Habitat modeling techniques, such as conditional logistic regression, require a random sample of background points used to quantify available habitat. One common assumption of resource selection functions is that animals have an equal probability of using background points as they do occurrence points. For animals that move across the landscape this assumption is often violated if the entire movement corridor is considered as background. This tool alleviates this concern by creating a local sample of background points around known occurrence points. There are two versions of this tool. The large version is recommended for most applications as it tiles the data resulting in faster processing times. It does this by using a parameter specifying the number of features per tile and then tiling (splitting) the dataset. The smaller datasets result in much faster run times and the results are appended to an empty output shapefile continuously.  If there is a power outage or some other interruption it should be possible to go back and determine how much of the dataset got processed and which points got processed.

The map on the left shows the original occurrence points as white dots and 10 random points around each occurrence as small black points. The new tool is available HERE . Other GIS tools are available as always from the download page on our lab's website HERE

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