Problem with Raster Calculator/burning streams

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12-26-2013 12:48 PM
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by Anonymous User
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Original User: dewey32167

Hello All,

I hope this will be a simple question.

I have a DEM that i am trying to burn streams into except that my streams are road side ditches.
I have converted the polylines into to a raster and i am trying to to burn them in using raster calculator but when i minus the difference between the two the only thing that comes back is the ditch. See pictures attached [ATTACH=CONFIG]30123[/ATTACH][ATTACH=CONFIG]30124[/ATTACH]

Any idea for a quick fix?

Thank you ahead of time




Additional note: I know about arc hydro tool set but it converts my DEM to meters which wouldn't be a problem except we have 70+ DEM to work with and are trying to automate this processes as much as possible
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MVP Esteemed Contributor
I suspect non-ditch areas are classed as nodata.  reclass that area to 0, then do the subtraction, otherwise you will end up with just the ditches

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MVP Esteemed Contributor
I suspect non-ditch areas are classed as nodata.  reclass that area to 0, then do the subtraction, otherwise you will end up with just the ditches

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by Anonymous User
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Original User: dewey32167

I suspect non-ditch areas are classed as nodata.  reclass that area to 0, then do the subtraction, otherwise you will end up with just the ditches


Thank you so much!

I ended up taking this one step further and Did a ISnull Function Then A Con Function to combine the DEMS.

For anyone interested i simply Did Isnull to my Ditches then did:
[ATTACH=CONFIG]30126[/ATTACH]
Null is the ISnull Raster
DEM_q29... is the background DEM
Ditch is the New Ditch that has been converted from a polyline to a Raster
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