topic Re: adding two rasters together in Data Management Questions

adding two rasters together

JoshuaGage — Tue, 21 Dec 2010 17:05:11 GMT

Good afternoon. I know this is simple but am missing something obvious.

I have two raster datasets that have cost-surface values. They both have the same extent (i.e. county boundary). The difference between the two is that one raster is a grid of land use and is continuous across the whole county. The other raster only represents public lands. Although it has the same extent as the whole county, there are some areas where there are no values (i.e. private lands).

I am creating a cost surface and want to add the two together. When I do this using raster calculator, the resulting grid only occurs where both datasets overlap. Am I taking the wrong approach to adding the two grids together? Any suggestions?

thanks in advance,

Josh

Re: adding two rasters together

RobertBerger — Tue, 21 Dec 2010 18:00:45 GMT

Hi Josh,

One thing you could try is to do a mosaic and use the mosaic method to specify what values come through. I'm not sure if this will work for you or not but it might.
Question: the private lands: what is the pixel value for all other values (not private)? I it NoData or 0 or something else?

Robert

Re: adding two rasters together

JoshuaGage — Tue, 21 Dec 2010 18:04:38 GMT

Robert,

Other lands (i.e. private) have a not data value.

update...

i reclassified no-data value equal to zero. when i then added using raster calculator, i got all the values i needed.

any other suggestions using raster calculator?

cheers,

josh

Re: adding two rasters together

RobertBerger — Tue, 21 Dec 2010 18:40:04 GMT

Josh,

You could also try using the spatial analysis CON tool. This is very similar to a programmatic "if" statement.

Robert