Replacing Raster Values

[GianlucaZampa]

Hi,
I'm working on a thesis about soil sealing and I'm using Arcgis 9.3. I have two rasters and I have a problem in replacing raster values from a raster to another one. In a few words I have two rasters Ras1 and Ras2 and I want to change the Ras1. For those interested areas of Ras1 having nodata cells and wrong data cells, I want to replace cell values with Ras2.
Is there any way to replace raster values in Ras1 with Ras2 of my chosen area in the image?

Thanks
Gianluca

[CarrieDavis]

Hi Gianluca ,

In version 9.3 you could use the Raster Calculator tool and map algebra to create a conditional statement. You will need to have the Spatial Analyst extension to use this tool. Add your rasters an ArcMap session, enable Spatial Analyst and open the Raster Calculator.  To replace a particular value in Ras1 with Ras2 you would enter.

Con([Ras1] == value, [Ras2], [Ras1])

Below are two how to articles on this topic.

HowTo:  Convert NoData values to other values for raster data
http://support.esri.com/en/knowledgebase/techarticles/detail/34932

HowTo:  Change a particular value of a raster dataset to zero without changing the other values
http://support.esri.com/en/knowledgebase/techarticles/detail/39974

Con tool documentation for 9.3
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?topicname=con_

Best wishes.