[postgis-users] Expand odd shapes

[Andy Colson]

At first I thought no, because it creates a circle around a point:

"Returns a geometry that represents all points whose distance from this Geometry is less than or equal to distance"

But now that I read it again, maybe it does do what I'd like.  If I pass a rectangle, it'll return all points <= radius.

I'll give it a shot and try it out.  Thanks for the help.

-Andy


On 06/09/2015 04:48 PM, Basques, Bob (CI-StPaul) wrote:
> Can you use ST_Buffer??
>
> bobb
>
>
>
>> On Jun 9, 2015, at 4:34 PM, Andy Colson <andy at squeakycode.net> wrote:
>>
>> Hi all.
>>
>> I have buffer selection problem.  My site can drop a point, then find all the parcels within 100 feet of that point.  No problem.
>>
>> One client however would like to select a parcel (maybe its a square, maybe its a triangle, or any other odd shape), and find all other parcels within 100 feet of any point within the source parcel.
>>
>> 100 is optional.  They could choose 50, or 150.
>>
>> I'm not sure how to do something like this.  I found ST_Expand, but that'll create a bounding box around the triangle.
>>
>> ST_TransScale could scale it, but I'm not sure what the scale is.  The user might type in 50 feet or 150 feet, I'm not sure how to calculate a deltaX and deltaY scale for that.
>>
>> Any hints on how I might go about this?  I'm a bit stuck.
>>
>> Thanks,
>>
>> -Andy
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