[postgis-users] Minimum Bounding Rectangle

[Brent Fraser]

Regina,

Yep, I used ST_LongestLine to confirm my length calc.  I didn't think my 
PostGIS fu was good enough to create a Postgresql function to find the 
width and construct a rotated bbox (maybe some day)...

Thanks!

Best Regards,
Brent Fraser

On 6/18/2012 11:28 AM, Paragon Corporation wrote:
> It's on my todo.  well first step of my todo anyway.
>
> http://trac.osgeo.org/postgis/ticket/1332
>
> Brent -- thinking of your idea
>
> Have you tried using ST_LongestLine?
> http://www.postgis.org/documentation/manual-svn/ST_LongestLine.html
>
> I'm hoping to get back to this ticket soon but tied up with other things.
>
> Thanks,
> Regina
> http://www.postgis.us
>
>   
>
>> -----Original Message-----
>> From: postgis-users-bounces at postgis.refractions.net
>> [mailto:postgis-users-bounces at postgis.refractions.net] On
>> Behalf Of Brent Fraser
>> Sent: Monday, June 18, 2012 12:37 PM
>> To: PostGIS Users Discussion
>> Subject: Re: [postgis-users] Minimum Bounding Rectangle
>>
>> Madison,
>>
>>     I went looking a few months ago, but could find nothing.
>> I wrote some PHP to:
>>       1. Find the length of the polygon (vertices farthest apart)
>>       2. Find the width (based on vertices farthest from length line)
>>       3. Build bounding box using length (with angle of the the length
>> line) and the width
>>
>> I'm still pondering the result when the input polygon is a square...
>>
>> But there should really be something like a
>> "ST_ExtentRotated" or "ST_RotatedBBox"  function in PostGIS.
>>
>> Best Regards,
>> Brent Fraser
>>
>> On 6/15/2012 2:03 PM, Madison Shaw wrote:
>>> Hi,
>>>
>>> I was wondering if any one could possibly offer some advice.
>>>
>>> I am wanting to calculate the area for a minimum bounding rectangle
>>> for individual polygon features.  I know I can use st_envelope or
>>> st_extent along with st_area but this doesn't quite give me the
>>> results I am after.
>>>
>>> For example if the polygon was already a rectangle but was
>> orientated
>>> on an angle the bounding box area is much larger than the
>> area of the
>>> original rectangle, whereas I would like it to be the same
>> value.  I
>>> suppose what I am after is a convex hull but as a
>> rectangle. Is this
>>> possible?
>>>
>>> Any help is greatly appreciated.
>>>
>>> Cheers
>>>
>>> Madison
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>
>>
>>
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