Friday, October 20, 2006

Calculating Area in ArcMap - Why should it have to be so hard?

I got a call from Keri Van Camp in Biology who wanted to know if there was a way to easily calculate the acreage of a region on a map. I assume she meant to draw a polygon and have an answer spit out in a window next to the polygon. Seems a simple GIS task to me. I recall that XTools used to be able to do something like that, but it is no longer free. It's available for a 30 day trial.

XTools costs $1,500.00 for academic institutions. I will look into getting this for all of the labs that have ArcMap in them (GIS lab, Sci Vis lab, Mobile mapping lab number one, Mobile map lab number two (Vassar Farm tablets)).

This is what they say about XTools: "Originally developed as a set of useful vector spatial analysis, shape conversion and table management tools for ArcView GIS 3.x. XTools extension was then converted by Data East to ESRI ArcGIS environment and now is re-designed, enhanced and extended as XTools Pro to get to the newer level of functionality and performance."
Anyway, back to trying to get Keri an answer, this is what I sent her:

Try one of these two ESRI ArcScripts:

Number 1
http://arcscripts.esri.com/details.asp?dbid=13941

ESRI Description: Adds and populates ACREAGE and/or AREA field to the attribute table of a dataset. Will properly calculate acreage for projected data, regardless of the linear units (meters, feet) used in that projection. Some other scripts I've seen DO NOT account for the projection and will give you wrong results. Tested on ArcGIS 8.1 thru 9.0. Includes a readme file showing how to install.

Number 2
http://arcscripts.esri.com/details.asp?dbid=13910

ESRI Description: The Areal Interpolator is an extension that uses simple areal interpolation to calculate a variable for a given area. The tool assumes the variable is distributed uniformly over the area.

Go to http://www.healthgis-li.com/researchers/User_Guide.pdf (pg 153 of 189) for complete instructions on how to use the Areal Interpolator extension.

1 comment:

I am Meg said...

Hurray! Keri figured it out. She used XTools. XTools costs money. We need to buy XTools.