[postgis-users] Using Postgis raster for water elevation

[Pierre Racine]

Or ST_Reclass() reclassifying everything > 10 to nodata...

> -----Original Message-----
> From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-
> bounces at lists.osgeo.org] On Behalf Of Rémi Cura
> Sent: Wednesday, May 27, 2015 9:31 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] Using Postgis raster for water elevation
> 
> Hey,
> 
> 
> Map Algebra?
> 
> (custom function with a thresholding?)
> 
> 
> 
> Cheers,
> 
> Rémi-C
> 
> 
> 2015-05-27 14:57 GMT+02:00 Gabriel Vatin <gabriel.vatin at kinaxia.fr>:
> 
> 
> 	Hello all,
> 
> 	I'd like to have some feedbacks on an operation that should be
> possible with Postgis raster, but I can't find out how to do this.
> 	I have a whole raster of French DEM (elevation data) stored on
> PostGis, with tiled objects. That makes a table with some 14.000 rows of
> data: france_mnt (rid, rast, filename)
> 	With ST_Value(france_mnt.rast, geometry), I can retrieve the
> elevation of a given coordinates in the geometry object.
> 
> 	I'd like to create a new raster, on the fly, with a maximum value of
> elevation, such as : all pixels with value < 10
> 	This could be used for mapping water elevation in a area, for
> instance.
> 
> 	Anyone has already done this? I'll be happy to have some tips on
> the function to use.
> 	Thanks!
> 
> 	Gabriel
> 
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