Ask A Cartographer

Area calculations from a .tif file

July 13 2011 | 3 comments
Categories: Map Data

I am working on a project to compare land uses in Arizona as a percentage of total land area. I am working with a tiff image from the USGS Land Cover Institute that has color bands representing various land uses, and I'm trying to calculate total area for each usage type. The file I have did not have a data table associated with it. I have no formal GIS training, so I'm working from online tutorials and the like. To add another wrinkle, the license I'm working with does not include the spatial analyst tools package. Most of the methods I am reading about require these tools. Is it even possible to do accurate area calculations without spatial analysis tools? Thank you in advance for any advice.

Mapping Center Answer:

I think most of your solutions for this will require Spatial Analyst as that is the extension that allows you to work with raster data such as a tiff. However, you could simply digitize the areas that you want to calculate the area for and then add a field and calculate the area. Here is a link to the help topic on how to calculate area.

More automated solutions will require the Spatial Analyst extension; however, as you are at an academic institution, you should actually have access to all the extensions! Please contact your site license manager to see about this. Once you get the extension, let us know and we can offer more automated solutions to this problem.

Geospatial Modeling Environment posted by Chris Pratt on Jul 22 2011 11:36AM
You need to check out SpatialEcologys (SpatialEcology.com) Geospatial Modeling Environment (GME). If I understand your problem correctly, you need to calculate the occurance of each classification down to the pixel. If this is true, the Mapping Center Answer is not a viable solution, but GME will work.

I faced a similar problem during a recent project. I needed to get area and percentages of GAP vegetation values within several watershed subbasins. GME worked like a champ.

Also, GME works with an ArcView license and does not require Spatial Analyst.

I hope this will help

Chris
Good tip! posted by Aileen Buckley on Jul 22 2011 11:43AM
Thanks for the tip, Chris! Sounds like a good one! Thanks for sharing this info with everyone!

If you would like to post a comment, please login.

Contact Us | Legal | Privacy |