[postgis-users] ST_Buffer + grid problem

[Pierre Racine]

1020x24798 so more than 25 000 000 polygons... or pixels...

So if I understand well you want to assign some values to each of those cells based on a vector coverage (of how many polygons)?

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
> bounces at postgis.refractions.net] On Behalf Of Ed Linde
> Sent: Thursday, March 22, 2012 4:43 PM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] ST_Buffer + grid problem
> 
> So far no proper raster, because the following failed, but maybe the polygon
> gives us an idea? This polygon is the extent of all the road geometries in
> Denmark. Also I remember that when you did the raster at your end you said it
> worked. Is 0.000036 degrees = 4m correct if I want to get a 4m by 4m cell sized
> uniform raster grid?
> 
> select ST_AsRaster( ST_GeomFromText('POLYGON((8.07734039737749
> 54.4984986588244,8.07734039737749 57.7505109647578,15.1919565742587
> 57.7505109647578,15.1919565742587 54.4984986588244,8.07734039737749
> 54.4984986588244))'), 0.000036, 0.000036);
> 
> 
> On Thu, Mar 22, 2012 at 9:39 PM, Pierre Racine <Pierre.Racine at sbf.ulaval.ca>
> wrote:
> 
> 
> 	> Thanks. The raster I need to visualise is a 4m by 4m grid on the entire
> map of
> 	> Denmark! :) So do you classify that as a large raster? If so is there a
> way to see a
> 	> portion of it or something?
> 	> I just want to manually check for a few areas on the map that the
> intersection
> 	> indeed works as expected and things haven't gone awry thanks to
> projection
> 	> differences or that I had degrees instead of meters or some such
> thing. Well, I
> 	> still have to first test if this GDAL upgrade will fix things and if make
> empty raster
> 	> .. makes a difference.
> 
> 
> 	That must be big but Danemark is a small country ;-) Only width and
> height tell you if a raster is big.
> 
> 	In the database, your grid is a set of rectangular geometry (how many?)
> or just a big raster now (width & height)?
> 
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