[postgis-users] Minimum Bounding Rectangle

[Madison Shaw]

Thanks Martin - Ill have a look at JTS - otherwise I think I will be
implemeting it based on the steps Brent mentions.

I believe ArcGIS 10 has a set of tool to create them as well - but
requires an info license.

Thanks everyone for the help :)

Madison




On 19 June 2012 04:39, Martin Davis <mtnclimb at telus.net> wrote:
> JTS has a class for computing a Minimum Bounding Rectangle:
>
> http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/algorithm/MinimumDiameter.html
>
> This may be in GEOS as well.
>
>
> On 6/18/2012 9:36 AM, Brent Fraser wrote:
>>
>> 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
>>> _______________________________________________
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>>> postgis-users at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>
>>
>>
>>
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