[postgis-users] Rounding the angle of the polygon

[Stefan Zweig]

Hi Christian,

i don't think that your task is a question that can be solved with typical GIS databases. At least postgis cannot. And I am quite sure that orcale & co. cannot either. Probably this would be a job to do with a adjustment package that allows to set angles as constraints. The Point is: to get one angle of the polygon correct you would have to move two other points which leads you into troubles with their enclosed angles.

I think taking the bounding box of the buildings will not help you, because most buildings have more than four corners, haven't they? Furthermore the bounding box would align all your building outline in north-south direction.

Have a look at adjustment /approximation software, just as http://www.xdesy.de/freeware/xdesy.html (german software, freeware) or similar products,


regards,

stefan


> -----Ursprüngliche Nachricht-----
> Von: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
> Gesendet: 17.01.08 20:02:20
> An: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
> Betreff: Re: [postgis-users] Rounding the angle of the polygon


> 
> Hi,
> 
> if I got your point of question correctly, why not calculating with the
> bounding box of relevant polygons?
> 
> Regards,
> Christian.
> 
> Am Donnerstag, den 17.01.2008, 09:32 +0100 schrieb Witteveen, Eduard:
> > Hello,
> > 
> > I have a large collection of polygons, where each polygon represents the shape of a building. The quality of the data is not perfect , but it can be used in a good way to give orientation in a map. However the problem is that not all the corners are 90 degrees, due to the quick-and-dirty way we gatherd the data. I want to change the corners, within a certain treshold (85-95), to become 90 degrees so it "looks" better on the orientation-map (and i think it will even improve the quality of my data, but im not sure of this).
> > 
> > Question: 
> > 	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?
> > 
> > Furthermore, i've did searches on the mailinglist/google/oracle/.. but i couldnt find any leads except for the "degrees" function but im not sure how this method could help me
> > 
> > Eduard Witteveen
> > 
> > 
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