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I want to make a map that shows my NDVI image (with 6 classess, natural breaks that I reclassified already)) that only contains zones with 500 cells or more and that are color coded to the area of each zones.

How would I do that? using which tools or function in arcmap? Im using ArcGIS 10.6

arcpy will help too

  • thanks for replying, i have edited my question. Trying to show Large area color coded by area. Thanks in advance – billy Jan 28 '18 at 20:56
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    I'm not on a computer with ArcGIS so not adding as an answer, but I would use the RegionGroup tool to generate zones, then filter by COUNT >= 500 using the Lookup tool. – user2856 Jan 28 '18 at 22:12

You could do a Raster to Vector operation, which, if you use a number or string as your raster 'attribute', then it will be grouped by classification.

That will mean you have vectors that can easily have an area attribute added, and then you can visualise that.

I don't think you'll be able to do it using a raster without some kind of bespoke scripting to export vectors anyway.

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    With some raster algebra, this can be done using zonal statistics. Coercing rasters to vectors sould always be a last resort and is rarely necessary. – Jeffrey Evans Jan 28 '18 at 21:49

If I understand you correctly, you would want to create two new interger rasters representing the desired class breaks and valid ndvi values reclassified to 1. You would then use zonal stats to create a raster representing the counts based on sums of the reclassified to one ndvi raster. This would result in a raster representing the number of valid ndvi values in each classified zone. You could then subset the original ndvi raster by using set null or con to make all values in zones with <500 cells nodata values. The advantage here is that in the step where you turn ten ndvi values to one, you could apply a threshold.

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