Creating a line at the intersection line of 2 DEMs

[DavidLoibl]

Hello,

I'd like to automatically create a line feature at the intersection of 2 DEMs. One DEM represents earth's surface, the other the snowline. The result should be a line feature that shows the snowline as it runs along the mountain slopes.
Any suggestions on how to achieve this would be greatly appreciated.

Cheers,
David

[MarkBoucher]

Welcome to the forum!

Can we assume that the DEMs cover the same area and that the difference between the two DEMs is the depth of the snow?

If so, with Spatial Analyst,

1. You can do raster math subtracting the earth DEM from the snow DEM.[INDENT]Toolboxes\System Toolboxes\Spatial Analyst Tools.tbx\Math\Minus
This will give you a depth raster. If the DEM grid cells where there is no snow is the same in both DEMs then the result of the subtraction will be zero. (side note: With the depth raster you can modify the symbology so the zero values have no color and the rest of the values are in a color ramp. You can then visualize the depth)

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2. You may need to run a Con() function to make all the non-zero values one  value such as 1. (Otherwise skip this and go to step 3). You use the Con() function in Raster Calculator or you can use the conditional tool Con.[INDENT]Toolboxes\System Toolboxes\Spatial Analyst Tools.tbx\Map Algebra\Raster Calculator
You could alternately use the Conditional tool in Spatial Analyst.
Toolboxes\System Toolboxes\Spatial Analyst Tools.tbx\Conditional\Con

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3.  With the raster with zero values where the snow depth is zero and 1 where the snow depth is greater than one, you should be able to convert the raster to polygon or polyline.[INDENT]Toolboxes\System Toolboxes\Conversion Tools.tbx\From Raster\Raster to Polygon
or
Toolboxes\System Toolboxes\Conversion Tools.tbx\From Raster\Raster to Polyline
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[DavidLoibl]

Dear MBoucher21,

thank you very much, your answer helped me a lot.

Steps 2 and 3 of your approach did not work well in my case, because the resulting line had many small intersections.

As an alternative, I used the "contour"-tool with the "dem1 minus dem2" result as input, "0" as base contour, and an interval high enough to make sure no other contours are drawn.

Kind regards,
David