[postgis-users] Rounding the angle of the polygon

Witteveen, Eduard ewitteveen at aaenhunze.nl
Mon Jan 21 00:04:43 PST 2008


Attila,

I'm fully aware of the consequences of rounding the degrees of the corners, which will automatically change the coordinates of the corners, this due to the fact that the direction of the borderline will change.

My first idea was(didnt make:
- Calculate the original weighted center of the polygon
- Describe the polygon as a ordered list of relative vectors (direction and length)
- Round the angle's
- Somehow fix the startpoint != endpoint (this should also give me a vector, which could be distributed evenly over the list of vectors, but i'm not sure if putting this in a loop it will end)
- Calculate the new weighted center and put this polygon with the center on the old center.

I now know that putting it outside the database is the way, i will now look which application/platform offers me the best tools.

Thank you for your response!

-----Oorspronkelijk bericht-----
Van: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net]Namens Attila
Csipa
Verzonden: 18 January 2008 15:27 PM
Aan: PostGIS Users Discussion
Onderwerp: Re: [postgis-users] Rounding the angle of the polygon


On Thursday 17 January 2008 09:32:08 Witteveen, Eduard wrote:
> 	Is there a way to round the angle of the corners to 90 degrees of a
> polygon, where the corner is between 85 and 95 degrees? If this can't be
> done in (pl)sql, what would be "the way" to do this?

From what you say this won't be easy - you can't change the angles 
of 'corners' unless you are altering the coords of the points (if you want to 
preserve straight sides for your polygons, that is). And if ARE changing the 
coordinates of the points, can you decide which points are on correct 
locations and which ones are skewed ?
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