Let's say I have a vegetation raster that indicates the density of forest all over the world. I also have a shapefile that contains the admin boundaries of each country in the world. The easy part is to make sure the grid cells are within the country boundary, but what I want to do afterwards is to create a separate polygon boundary that will surround the region in question. It is best to do it dynamically based on a certain density threshold, that could vary from country to country. I haven't exactly figured out how to handle that yet, but once I do, how would I go about encasing that data within a polygon that can be saved as another shapefile. I have attached an image of what I want the result to look like. Polygon

So after a threshold is determined, a polygon will be drawn around the area as tight to the boundary as possible, excuse the freehand above, and then output it as a new shapefile. Is this possible and any ideas on how it can be done? Would using Model Builder be feasible to create a tool that would take the density shapefile, boundary shapefile, and threshold value as inputs to produce a polygon?

  • You might find these discussions useful: gis.stackexchange.com/questions/8/…
    – Branco
    Aug 5 '14 at 17:52
  • Indeed they are, turns out though, I have a raster file and not a shapefile like I thought, so that opens a whole other can of worms. OP fixed to reflect this.
    – twistr25
    Aug 5 '14 at 19:09
  • This question seems to be almost identical to the one at gis.stackexchange.com/questions/102468/…. How, if at all, does it differ?
    – whuber
    Aug 5 '14 at 19:21
  • Looks pretty similar. I'll try some of those techniques and see what I can come up with.
    – twistr25
    Aug 6 '14 at 12:19
  • I'm going to be honest @whuber, that is beyond my capabilities most of what you discussed in that post. I have resorted to using focal statistics to create a point shapefile of the region I want, and it seems like it should be really easy to trace an outline of the points, but I am having a real hard time figuring out how to do that.
    – twistr25
    Aug 6 '14 at 15:45

Is it possible to Convert Raster to Polygon, then use the polygons in one of the tools referenced by Branco's comment?

Feature Outline Masks

Minimum Bounding Geometry

  • I tried this, but my values are fairly small and it requires the Raster values to be integers. I'm sure there is a way around it, like multiplying by a large number then re-dividing later, but when I first did it, I got really large grid cells that were no longer representative of the area I was working in. But I am exploring this option as well.
    – twistr25
    Aug 6 '14 at 12:21

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