topic Re: How to create Circle Polygons with minimum area inside of other Polygons? in Mapping Questions

How to create Circle Polygons with minimum area inside of other Polygons?

PhilipUrban — Tue, 05 Mar 2019 17:46:47 GMT

I have a Feature Class with Polygons to show areas, which fit to different characteristics I chose. In this case the Polygons show a combination of a landcover classification and the slope of the terrain. The goal is to find possible landing spots for helicopters. I extracted the areas with no forest oder any other obstacles out of the landcover classification and the areas with a maximum slope of 8° out oft he terrain model.

This leads to the polygons where helicopters can land, but one characteristic is missing: the area, a helicopter needs to land.

To use the shape_area isn’t an option, because it does not validate the shape of the area.

How can i find cirlces with a diameter of 22m, that are completely contained inside of the described polygons?

I tried the Feature to Point Tool and buffered the Points with 11m. But there is only one point per Polygon and i need to find circles of 22m diameter anywhere inside the Polygons and not only around the center.

Thanks for your help,

cheers

Re: How to create Circle Polygons with minimum area inside of other Polygons?

Anonymous User — Tue, 05 Mar 2019 18:55:50 GMT

Hi Philip,

You could try creating a sampling of multiple points within the polygons using either the Create Fishnet tool, or the Create Random Points tool. From there you could create the 22 m Buffer and use a Spatial Join to identify the circles entirely within the no-forest areas.

Additional Documentation: http://gis.mtu.edu/wp-content/uploads/2012/06/Regular_Sampling_Tutorial.pdf

Hope this helps. Let me know if there are any questions.

Re: How to create Circle Polygons with minimum area inside of other Polygons?

JoshuaBixby — Tue, 05 Mar 2019 21:39:17 GMT

i need to find circles of 22m diameter anywhere inside the Polygons and not only around the center.

Once you have a polygon large enough to hold a 22m diameter circle, there are an infinite number of locations (assuming infinite precision) in that polygon where a 22m circle can be centered. For example, below is a square with 12 circles centered at random locations in the square.

In terms of landing a helicopter, there is nothing unique or special about the 12 locations above since everywhere in the square has the same land classification/attributes.

Re: How to create Circle Polygons with minimum area inside of other Polygons?

PhilipUrban — Wed, 06 Mar 2019 08:18:34 GMT

Thanks for your help!

Creating Random Points inside the Polygons and then buffer them worked very good. When I do the spatial join, i get the complete Polygons where helicopters can land. But I need the buffered Points, which fit into these polygons. It's a matter of selection, but I don't get, how to select only the fitting buffered Points.

Do you have a hint for me?

Re: How to create Circle Polygons with minimum area inside of other Polygons?

Anonymous User — Wed, 06 Mar 2019 17:56:29 GMT

Sure! As I understand, we would want to select all 22m circles that fit entirely in the non-forested polygons. Here is are the criteria I used for my Spatial Join (or Select by Location) when testing this:

Target Feature: Buffer
Join Feature: Polygon
Join Operation: One to One
Keep All Target Feature: Unchecked (we only want the matching ones)
Match Option: Completely within

Select By Location: graphic examples—Data Management toolbox | ArcGIS Desktop

Hopefully that helps!

Re: How to create Circle Polygons with minimum area inside of other Polygons?

PhilipUrban — Thu, 07 Mar 2019 10:29:19 GMT

Hello Claire,

thank you very much for your help! My issue is solved, so i can continue with my Master Thesis