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How to create polygons from a raster by using specific RGB values

Question asked by danivbb0 on Feb 10, 2019
Latest reply on Feb 11, 2019 by danivbb0

Hi everyone,

I would like to create polygons, from a hardcopy map, which encloses the yellow, orange and red areas on the (hardcopy) map. (Please see attached 'NZ-CommercialFishing-AllMethods-A4-2.tiff'.) My approach so far has been to convert the map from a pdf to tiff file format, georeferencing and then manually creating the polygons. Manually creating these polygons is taking a really long time to do (two weeks and counting) and was hoping there was a quicker way of going about it. I'm considering cells with RGB values that meet the following criteria to be enclosed in a polygon: R > 200 && R > = G. (I'm using ArcMap 10.4.1 desktop and have access to quite a number of extensions.) 

 

Any help would be greatly appreciated!

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