[postgis-users] Expand odd shapes

[Andy Colson]

Huh.  My email from last night didnt make it though.

Sorry to spam the list.  This is my last one, I swear.

ST_Buffer was exactly what I was looking for.

Thanks Bob for pointing me back the right direction.

-Andy


On 6/10/2015 8:31 AM, Andy Colson wrote:
> Like this:
>
> http://testmaps.camavision.com/map/cassmo?pin=080834303000032000
>
> The blue part is the selected parcel.  The gray is the ST_Buffer.
>
> -Andy
>
>
> On 6/10/2015 8:27 AM, Andy Colson wrote:
>> Because I actually need to see the shape.  One step is to see the shape,
>> the second will be to find the parcels that touch it, which will use
>> ST_DWithin for speed plus ST_Buffer for accuracy.
>>
>> -Andy
>>
>>
>> On 6/10/2015 1:43 AM, Rémi Cura wrote:
>>> Why not use ST_DWithin with the original triangle, it is the best option
>>> regarding speed and precision.
>>> Cheers
>>> Remi-C
>>>
>>> Le 10 juin 2015 01:30, "Andy Colson" <andy at squeakycode.net
>>> <mailto:andy at squeakycode.net>> a écrit :
>>>
>>>     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 <mailto: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