Using ArcGIS Desktop, how do I extract a certain area (uniform 1 km from the entire coastline) from a particular year's DEM image?
To achieve this you would need to use a combination of raster processing tools, a bit of editing then buffer and extraction.
The Initial workflow would be this model:
- IsNulll creates a binary mask of land and nodata.
- Majority filter (set neighbours to use to EIGHT) removes small pixels of nodata
- Focal Stat tool is set to SUM values and this captures the edge
- Reclassify allows you to pull out specific pixels at edge and convert rest to NODATA
- Convert the reclassified pixels to a vector line
The output would be this:
Note that there was nodata in the middle of the DEM so these have come out and generate polylines, you would need to select and delete these out, also delete the obvious edge of raster lines (may require you to split the line with split tool) so you are left with just the coastal edge.
Then as Michael suggests buffer the polyline (make sure you set Dissolve type to ALL) and then use extract by mask, the final output is as below:
Red line is the polyline coastline you had edited, grey is the extracted section (1Km) and background is the source DEM data.