[Qgis-user] Edit raster (DEM) values with polygon

[Doug Johnston]

Hello all.

I am attempting to edit (change) the values for all pixels in a DEM in
region of the DEM.

The real-world problem is I want to burn in a proposed flood wall/dike into
an existing DEM.

I have a polygon with the desired elevation field, and I also have a raster
with the desired elevation values (rasterized from the polygon).

I have looked at rasterize tool, however cannot find the correct way burn
the overlying polygon into the dem (referencing an attribute field), or if
it is even possible.

I would also think raster calculator would do it with the two rasters, but
I do not have the syntax down:

pseudo-code: if dike-dem is_not "no_data" |> use dike-dem; else use
original-DEM.

Here is a screen shot of the two rasters.

All help is appreciated; thanks in advance.

Doug Johnston
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