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I'm looking for solutions to this in ArcMap 10.2.2 Basic, with no Spatial Analyst extension.

I am trying to find parcels that have been damaged by a large fire. I have a raster image showing the burn path and surrounding areas. I'm overlaying a parcel layer on top of the raster and would like to extract polygons on top of raster cells that have a specific RGB range.

Here is the image: enter image description here

The dark red and black pixels always have a red value > 180 and < 210 with green and blue values less than 50. The lighter pixels all have RGB values > 200.

The raster has no attribute table as it is a multi band image. I converted it to a single band but the values are no longer discernible in the burn path from other areas of the image.

I then tried converting the raster to points. Still, no distinct values for the burn path.

Is there a way to select polygons using a specified pixel RGB range?

  • 1
    Have you tried converting your raster to a polygon after re classifying the values? Then select by location with polygon? – whyzar Oct 17 '17 at 18:50
  • @whyzar I converted to polygons but there is nothing to reclassify with except grid codes. Sampling these I get pixels inside and outside the burn path. I need to somehow get distinct R values, not an average of RGB (I believe this is what single band and polygon/point conversions do). – geoJshaun Oct 17 '17 at 19:14
  • Please decide which of ArcGIS Desktop and QGIS you wish to ask about in this particular question. That way you and potential answerers will be able to focus on precisely what you have tried and where you are stuck using that. You can always ask about the other separately. – PolyGeo Oct 17 '17 at 19:18
  • @Polygeo. I did specify what I had tried already. I don't see how I could be more specific as to the problem I'm having. Limited it to ArcGIS. – geoJshaun Oct 17 '17 at 19:49
  • what you're looking for is raster statistics in polygon, you are getting closer, have a look to the first answer: gis.stackexchange.com/questions/212107/… – Elio Diaz Oct 17 '17 at 20:59
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I'll try to find "white" parcels on this image without using Spatial Analyst:

enter image description here

  • Convert raster to points. This extracted red band values into the point layer
  • Select points in layer table that "match" white pixels
  • Intersect points with parcels
  • Use summary statistics to find count of "white" points inside individual parcel
  • Transfer that count to parcel table:

enter image description here

If you need to analise all 3 bands export RGB to grid and do similar thing with each. You might as well convert count of points inside individual parcel into ratio of burned area, because you know cell size and parcel area.

  • I ended up exporting the B band and selecting the low values and then converting them to points. This isolated the burn path values fairly well. Had to do a little manual clean up but it got most of the job done. Thx! – geoJshaun Oct 18 '17 at 21:52

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