Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon
Area of Irregular Polygon Area of Irregular Polygon
Area of Irregular Polygon
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Old 06-08-2012, 08:19 AM
holtzy holtzy is offline
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Talking Area of Irregular Polygon


I have searched and found several ways of finding the area of an irregular polygon. However, none of them are giving me the correct area. I have an array of pointF that I need to calculate the area of. I have tried using forumlas like http://blog.open-design.be/2009/03/0...gular-polygon/, but it is not even close to correct. I have tried breaking it into triangles using http://www.codeproject.com/Articles/...ngulation-in-C, but it gives me incorrect area randomly.

I would really prefer not to use triangulation. Are there maybe limitations to these methods that would make it not work for the attached polygon (see polygon.jpg)?

I have also attached a sample project that includes the points for the polygon. Any help or direction would be greatly appreciated.
Attached Images
File Type: jpg polygon.jpg (5.3 KB, 2 views)
Attached Files
File Type: zip SketchAreaTesting.zip (72.9 KB, 10 views)
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Old 06-08-2012, 09:38 AM
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passelArea of Irregular Polygon passel is offline
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I haven't had to do anything like that before, but just looking at the figure I wonder if it wouldn't be easier to figure out the bounding rectangle (simple), then work your way around the figure and determine the area outside the figure and subtract that from the bounding rectangle area.
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Old 06-08-2012, 09:50 AM
holtzy holtzy is offline
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Thanks for the idea, I never thought of that. I'm not sure how I would get the outside area though. This is just a sample polygon. It can really change to about any shape of irregular polygon.
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Old 06-10-2012, 03:31 AM
surfR2911 surfR2911 is offline
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Default area of an irregular polygon

Here is the vectors into coordinates method (using positive and negative widths).

A good starting point for polygon area calculation using VB.Net code might be
this vbHelper code.

Browsing through this "Polygon and irregular area calculation" VB.Net article might also be of some interest.

An explanation of the Surveyor's Area Formula is here.

This article is also notably cited, but with the caveat that it doesn't work in self intersecting areas,
(I don't know if your algorithm/methodology needs to handle those special cases, but probably a self-intersected polygon can just be regarded as a number of non-intersected polygons).

There are some good diagrams towards the bottom of this page.

Last edited by surfR2911; 06-10-2012 at 04:11 AM.
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Old 06-11-2012, 12:33 PM
holtzy holtzy is offline
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Thank you guys so much for all the help and links!
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Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon
Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon Area of Irregular Polygon
Area of Irregular Polygon
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Area of Irregular Polygon
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