Draw a polygon automatically around points,

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02-16-2016 02:21 AM
MajdoleenO_A__Awadallah
Occasional Contributor III

Draw a polygon automatically around points,

I am looking for a way to draw a polygon automatically around points that have similar value in one field of the attribute table.


For example, in the screenshot below, I wanted to draw a polygon around the points that have class B, and to have the points inside the curved polygon but not as if they are at the boundaries (not like minimum boundary geometry tool).

boundary.jpg

Thank you in advance,

Best,

Majdoleen

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13 Replies
XanderBakker
Esri Esteemed Contributor

You should probably use Thiessen polygons to get a simular result. See Create Thiessen Polygons—Help | ArcGIS for Desktop followed by dissolving on the attribute. Create Thiessen Polygons requires an advanced license, but Dan Patterson​ has created a tool for Basic license that creates them too.

Dan Patterson​, can you add the link to that tool? Thanks!

MajdoleenO_A__Awadallah
Occasional Contributor III

Thank you Xander, but my point here that I want to produce smooth curved polygons around the points that have similar value as shown in the screenshot.

Best,

Majdoleen

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XanderBakker
Esri Esteemed Contributor

You can apply a negative buffer after the dissolve step.

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XanderBakker
Esri Esteemed Contributor

Or better yet, use the Smooth Polygon—Help | ArcGIS for Desktop tool (Advanced license required)

DanPatterson_Retired
MVP Esteemed Contributor

Xander...

Called... Triangulation Tools ...since it does both Delaunay and Voronoi

XanderBakker
Esri Esteemed Contributor

Thanks Dan, I will bookmark it (include it in my local Wiki)

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XanderBakker
Esri Esteemed Contributor

I do wonder how you are going to manage the points identified with the letter "A". If I create Thiessen polygons the "C" polygon does not connect since the A points are nearer:

as you can see here (after dissolving):

Applying a negative buffer and Smooth polygon with the PEAK setting doesn't really get us there:

The BEZIER setting gets a little closer, although it still isn't the result you sketched.

MajdoleenO_A__Awadallah
Occasional Contributor III

Thank You, It is very helpful, but the only thing that missing here is: I want all the A's in one single polygon!!

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DanPatterson_Retired
MVP Esteemed Contributor

The A's can constitute a multipart polygon... that is a polygon that consists of discrete separated areas but share a common record in a table.  There is no way that you are going to get the geometries together into one physical polygon... unless you draw it yourself ...

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