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Is there an easy way to get just the "data" footprint for a raster. I have 3 DEMs and a tile layer. I'll be using the tile layer for referencing tiles of contours and ultimately I want to flag tiles along the edge (with a field) as "incomplete" if the entire tile isn't covered by data.

I tried to use gdaltindex because I remembered using it to create reference layers for imagery and I figured it would do what I want but the result includes all the NoData in the extent of the image and I can't seem to get around that. I was hoping to do a quick selection of the tiles that are "completely contained" and then switch selection to get the ones that are outside the "data" area.

I figure I can (as a last resort) just render the DEMs as all values of 1 and mask out the NoData values and then convert to polygon but I was hoping there was an easier way?

I can make use of a QGIS or ArcMap solution if someone has one.

Desired Result

jbchurchill
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  • Check the answers to this old question http://gis.stackexchange.com/questions/61512/how-to-calculate-image-boundary-footprint-of-satellite-images-using-open-sourc. The "create alpha - polygonize alpha" route should at least work. – user30184 Jun 27 '16 at 09:08

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There really was no easy way for me to complete this other than what I suggested in the first place which was to "render the DEMs as all values of 1 and mask out the NoData values and then convert to polygon". Technically I converted the NoData to 0 and all valid pixels to 1 with this Con Statement ...

Con(IsNull("myDEM"), 0, 1)

and did away with the "0" polygon. At this point I could have used the "Image Boundary" plugin with QGIS as the commenter @user30184 suggested but I opted instead to use Raster to Polygon in the "Conversion Tools"->"From Raster" Toolbox in ArcGIS since I was in there already. I noticed that the author of the Image Boundary plugin indicated that the NoData values had to be zero in order for the "valid pixels" output to create the desired result. The resulting polygon had the values of 0 and 1 but that got me close enough to finish the task.

jbchurchill
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