[JPP-Devel] Shape analysis using area-perimeter ratio
I had a need to classify polygon shapes into general categories such as roads and buildings, and I though it might be possible to use a thinness factor calculated using the area and perimeter. After fooling around with it for a while and not getting the answer, I goggled and found the following solution: Slide 11 lCircularity ratio: the ratio of the area of the shape to the area of a circle (the most compact shape) having the same perimeter. (area-perimeter ratio) M = ( 4 * Pi * Area of Polygon) / (Perimeter of Polygon)^2 For a circle, the ratio is one; for a square, it is π / 4; for an infinitely long and narrow shape, it is zero. I found it at: http://ce.sharif.edu/~alamgir/ Further searches indicate that this method of classification may be relatively unknown. Does anyone have knowledge in this area? regards, Larry Becker -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd___ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
Re: [JPP-Devel] Shape analysis using area-perimeter ratio
Hi Larry, I don't know if this ratio is often used in geomatics, but I implemented it in a plugin available on the site : https://sourceforge.net/projects/jump-pilot/files/p_%20More%20Plugins/OJ%20graph%20toolbox/ I called it circularity and defined it as an integer (where 100 means perfect circle) When I did it, my need was to recognize roundabout on a linear network, so that it does't work only on a polygon layer, but also on a linear network (where cycles are detected by the JGraphT functions, and transformed into polygons) The plugin creates also a few other indicators. Let me know if it's useful or if it has to be improved for your use-case. Michaël Le 27/04/2011 23:00, Larry Becker a écrit : I had a need to classify polygon shapes into general categories such as roads and buildings, and I though it might be possible to use a thinness factor calculated using the area and perimeter. After fooling around with it for a while and not getting the answer, I goggled and found the following solution: lCircularity ratio: the ratio of the area of the shape to the area of a circle (the most compact shape) having the same perimeter. (area-perimeter ratio) M = ( 4 * Pi * Area of Polygon) / (Perimeter of Polygon)^2 For a circle, the ratio is one; for a square, it is π / 4; for an infinitely long and narrow shape, it is zero. I found it at: http://ce.sharif.edu/~alamgir/ http://ce.sharif.edu/%7Ealamgir/ Further searches indicate that this method of classification may be relatively unknown. Does anyone have knowledge in this area? regards, Larry Becker -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd ___ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd___ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
Re: [JPP-Devel] Shape analysis using area-perimeter ratio
We implemented this as part of the JCS Conflation Suite (which was the reason JUMP was originally developed!) There's a whole body of theory around shape recognition - much of which is very complicated and hard to implement/use. The circularity ratio is one of the more usable techniques. Martin On 4/27/2011 2:00 PM, Larry Becker wrote: I had a need to classify polygon shapes into general categories such as roads and buildings, and I though it might be possible to use a thinness factor calculated using the area and perimeter. After fooling around with it for a while and not getting the answer, I goggled and found the following solution: lCircularity ratio: the ratio of the area of the shape to the area of a circle (the most compact shape) having the same perimeter. (area-perimeter ratio) M = ( 4 * Pi * Area of Polygon) / (Perimeter of Polygon)^2 For a circle, the ratio is one; for a square, it is ? / 4; for an infinitely long and narrow shape, it is zero. I found it at: http://ce.sharif.edu/~alamgir/ http://ce.sharif.edu/%7Ealamgir/ Further searches indicate that this method of classification may be relatively unknown. Does anyone have knowledge in this area? regards, Larry Becker -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd ___ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel No virus found in this message. Checked by AVG - www.avg.com http://www.avg.com Version: 10.0.1209 / Virus Database: 1500/3600 - Release Date: 04/27/11 -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd___ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
