Add (SUM) Multiple Rasters of different extents

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02-15-2011 10:31 AM
MichaelMarkieta
New Contributor III
I am having trouble adding multiple rasters to create an overal classifications raster.

Currently, I have 3 criteria variables (polygons), which have been converted from vector to raster. Each raster represents a different extent of spatial coverage on my map (eg, highways, land usage, pop density by Census Tract... I am creating a human influence index)

I will use a simplified grid example, such as those used in the ArcMap help/resources.

Below you will see the addition (summation) of 3 raster grids, with the output that I am currently experiencing. This is NOT what I would like. (grey = nodata)



Here is an example of what I would like to happen.



I've spent too much time trying to figure this out. I hope someone can steer me to the right tool or option/setting?

Note: I am using ArcMap 10
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15 Replies
profchamberlain
New Contributor
Precisely! (Apologies if you do not have that version)
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deleted-user-IR249IovB3CN
New Contributor III
The method of using Cell Statistics with a raster of values = 0 covering the entire analysis extent worked, as described above. I had issues initially with an inaccurate extent so I set some environmental parameters of the tool. They were: Set output coordinate system, set the processing extent "union of Inputs", set the 0 raster as my snap raster, and in Raster Analysis settings I set the cell size and mask to the 0 raster. After doing this the tool worked. ESRI, if your listening, a blog post would be useful to share this process/fix with the greater community.

Thank you for your help.
AndrewKamerosky
New Contributor
Ok, I am having no luck in following what y'all have done.  I have the same task, multiple (100+) rasters of different extents and most not overlapping (But in the same area) that I am simply trying to sum the values (0,1).  The map is going to show how many times a given cell was "treated". All the rasters have had the noData changed to 0 (Using the reclassify tool, a lot easier than raster math).

So I tried to do the cell statistics.  The first attempt started with the creation of a basemap of pixel values of 0, which covers all the other cell locations.  I then entered a subset of maps (for the one year) that included the basemap. I set it to run "sum". I then set the environment settings as mattlove described (set spatial, snap raster, raster analysis settings to the basemap and chose untion of inputs).  But I still get "Invalid Output Extent".  When I set the Processing Extent to the basemap, it runs but the output is blank/corrupted/I have no idea why there's no data.

What've done, just so I can get this rolling while someone else can help me figure out whats going wrong, is mosaic the pieces to the basemap (Using Mosaic to Net Raster).  Then I can use the Cell Statistics tool to sum all the maps now that they are all the same size.  This process is not time efficent at all, I've tried building a model to run this but that hasn't worked out yet. 

Please tell me ESRI has created a tool that does this or help me figure out what I'm doing wrong with Cell Statistics that it won't cooperate.
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deleted-user-IR249IovB3CN
New Contributor III

Stumbled across this issue again. Solution: Create a continuous raster with value = 0. Run Cell statistics with all desired rasters, including the continuous raster. The Overlay Statistic = "Sum". Be sure to set "processing extent" in environment settings to "Union of Inputs". 

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MaryCoburn1
New Contributor

In the environment settings (at the bottom of raster calculator) set the processing extent to Union of Inputs.

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PhillipBurrows
New Contributor

Easy fix: use Cell Statistics tool. Select SUM as your 'Overlay Statistic' and check the Ignore NoData in calculations box

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