[postgis-users] create 1 cell/polygon per point inside bounding polygon

[Daniel Cole]

Thanks Brent for the good info.  You are always good help on this list..

And thanks as always Simon. Your St_Voronoi is going to do exactly what I
need done.

Simon has been a great resource over the last year to me and continues to
provide with this script.

Many Thanks,

DC

-----------------------------------------------------------
Daniel Cole



On Sat, Sep 8, 2012 at 10:30 PM, <pcreso at pcreso.com> wrote:

> Hi Daniel,
>
> Do you want regular cells or polygons?
>
> There are a few approaches for generating voronoi polygons in Postgis:
>
> eg:
>
> http://www.bostongis.com/PrinterFriendly.aspx?content_name=postgresql_plr_tut02
> http://geogeek.garnix.org/2012/04/faster-voronoi-diagrams-in-postgis.html
>
> If your points already represent the centre of cells, then a fishnet
> approach would work, generate a mesh to match the grid, then do a spatial
> join on points inside cells to generate the match. You just need to know
> the extent & size of the grid:
>
> http://trac.osgeo.org/postgis/wiki/UsersWikiCreateFishnet
>
>
> HTH,
>
>    Brent Wood
>
> --- On *Sun, 9/9/12, Daniel Cole <daniel at southernsolutionsms.com>* wrote:
>
>
> From: Daniel Cole <daniel at southernsolutionsms.com>
> Subject: [postgis-users] create 1 cell/polygon per point inside bounding
> polygon
> To: postgis-users at postgis.refractions.net
> Date: Sunday, September 9, 2012, 3:02 PM
>
>
>
> I want to be able to take a polygon that has 3 to 50 points inside of it
> and create polygon where each point is the only point inside of it a cell
> and it is located at the centroid, or at least close. The points are
> already in a sort of grid shape, so want my cells as uniform size as
> possible although I assume the cells containing the outer-most points may
> be larger or smaller.  Any cell on the outer edges will be clipped by the
> original bounding polygon.
>
> I  thought that I might could use something like fishnetting, but I want
> to be sure that there are just the same number of cells are there are
> points.
>
> I have attached an image that I made using the nearest neighbor algorithm
> and I think and the look is basically what I wanting to do, but where you
> see the color there, there would be a cell unique to that point. If anyone
> knew anway to reverse that raster into cells that would help too.  thanks.
>
> any thoughts?
>
> DC
>
> -----------------------------------------------------------
> Daniel Cole
>
>
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>
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