topic How exactly does the Point Density tool calculate cell values in SA? in ArcGIS Spatial Analyst Questions

How exactly does the Point Density tool calculate cell values in SA?

DouglasSharp — Thu, 08 Mar 2012 21:24:57 GMT

I used the NONE value in the Population field and set a search radius such that many of the cells in the output raster included only a single point within their search radius.

I was expecting that these cells would have a value of 1.0 but they don't.

Here are input parameters for two runs of the tool:

Population field: NONE
Output cell size: 30
Neighborhood: Circle
Radius: 400
Area units: SQUARE_KILOMETERS

Cell value in cells that have a single point within the search radius: 1.989437

Population field: NONE
Output cell size: 30
Neighborhood: Circle
Radius: 500
Area units: SQUARE_KILOMETERS

Cell value in cells that have a single point within the search radius: 1.273239

Shouldn't the pixel values in both of these output rasters have been 1.0?

How exaclty are output raster cell values calculated in the Point Density tool?

Thanks

Doug Sharp

Re: How exactly does the Point Density tool calculate cell values in SA?

GayathriAlallasundaram — Thu, 08 Mar 2012 21:29:47 GMT

Hi,

Here is a link that gives information on how point density works,

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009z00000013000000.htm

-Gayu

Re: How exactly does the Point Density tool calculate cell values in SA?

DouglasSharp — Thu, 08 Mar 2012 21:46:58 GMT

Ah yes - was thinking that the average density would be the same for each pixel. Forgot that the count is divided by the total search area.

Thanks