# Using Raster calculator with ModelBuilder?

I am making a model in ModelBuilder and there is a problem with Raster calculator result. I have to rasters with 0 and 1 values, I want to know where do they intersect and make a new raster with value 1 in that places. In Raster calculator I put the expresion like: raster1 * raster2. The problem is that it returns empty raster (with 0 values only), but when I look at rasters I can clearly tell that they do intersect. Does anyone know what the problem can be?

• Make sure the projection are the same, just in case – gisnside Apr 4 '17 at 13:06
• There is same projection, but thanks to your comment I will check the resolution. – W. Tom Apr 4 '17 at 13:20
• That could also be a good reason :) – gisnside Apr 4 '17 at 13:23

## 2 Answers

In order to do what you are trying to achieve you need to do a 2 step process:

1. Use Raster Calculator and calculate Raster1 + Raster2.

This will give you a new raster with:

Values of 0 where both Raster1 and Raster2 have values of 0.

Values of 1 where one of Raster1 or Raster2 has a value of 1 and the other has a value of 0.

Values of 2 where both Raster1 or Raster2 have a value of 1.

The cells with a value of 2 are the ones you are interested in. But you said you want these to have a value of 1.

1. You can now use the Reclassify tool to reclassify your new raster. Using this tool you can reclassify you raster so that all values of 2 become 1.

Depending on what you are trying to do, you might also need to reclassify the cells with a value of 1 to something else so that you can still differentiate between these and your new value 1 cells.

• Sorry, I made a typo, I want new raster values to be "1" where old raster values "1" intersects and "0" in other cases. – W. Tom Apr 4 '17 at 13:19
• Have changed my answer accordingly. When using the reclassify tool, just reclassify the 2's to a 1. – Dan_h_b Apr 4 '17 at 13:37
• It sounds like OP's problem was unrelated, but in the general case, why would we expect addition to work when multiplication fails? Is this a workaround to a known bug with multiplication, or is something else at play? – Joe Apr 4 '17 at 15:29
• This doesn't seem to be what the OP wants. The OP seems to be interpreting 0 as "no value at this location." So "intersection" would be the cells where both rasters have a non-zero value, no? – jpmc26 Apr 4 '17 at 17:18

There was a problem with different resolutions :) The problem is solved