[GIS] Calculate Number Of Pixels Visible From Pixel

demgdalspatial-analystviewshedvisibility

I am looking for a way in which to take an input DEM and create an output raster whose pixel's value is the count of pixels "visible" from that location.

I use ArcGIS with Spatial Analyst, but also Manifold, GlobalMapper or GDAL.

How would I go about this task?

Best Answer

In ArcGIS you can use the Viewshed tool (Spatial Analyst Tools > Surface). The Viewshed lets you calculate the surface locations visible to a set of points or lines (see the documentation).

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ArcGIS-Desktop Raster Selection – How to Select Pixels in Raster Using Polygon Selection Tool

Edit your polygons to cover where you want to change the landcover raster, be sure to use the same pixel codes, for example if grass = 8 then make sure your grass polygons has a numeric field with a value of 8. It is also best for the vector to be in the same coordinate system as the raster.

Set your environments snap raster and extent to match your existing landcover raster and convert polygon to raster using the value field which matches the classes, be sure to use the same cell size as your existing raster, this will ensure your cells match exactly. Your polygon raster will now have values where the polygons are and everything else should be nodata.

Using the Raster Calculator use an expression like:

Con(IsNull(PolyRaster),OriginalLandCover,PolyRaster)

Substituting the values for your polygon raster and landcover raster, this will use original landcover where your polygons aren't (is null) and polygon raster where a value exists (is not null). The Con tool is a true/false decision tool, paired with IsNull which is true where the raster is NoData and false where it has a value.

Best Answer

Related Solutions

ArcGIS-Desktop Raster Selection – How to Select Pixels in Raster Using Polygon Selection Tool

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