RASTER layer functionality, a SWAQ

[Paul Ramsey]

John,

I think by following Frank's advice and using a PostGIS-hosted tile- 
index you can do a hell of a lot by manipulating your DATA statement  
to get the images you want for a given request.  Things like temporal  
subsetting, etc, are all pretty easy. You don't even need to use  
mapscript, just override your DATA statement with a parameter in the  
mapserv CGI. (I think mapscript is largely irrelevant given the  
capabilities of the CGI system, personally.)

Paul

On 25-Aug-06, at 9:55 PM, Frank Warmerdam wrote:

> John Novak wrote:
>> I have a large number of rows containing metadata about rater  
>> files sitting in a PostGIS table.  Each row is associated with a  
>> georeferenced file sitting in a file system, and the row contains  
>> polygon geometry representing the footprint of the raster.  The  
>> rows also contain many other attributes that I'd like to use to  
>> filter the displayed rasters.
>> Having the functionality of the RASTER layer, but using a PostGIS  
>> table as a source for features rather than a SHAPEFILE would be a  
>> very useful thing, at least in my case.
> >
>> What's the opinion regarding
>> 1. the overall usefulness of such a beastie
>> and
>> 2.  the complexity of actually implementing said beastie, given  
>> that it's a combination of the functionality of a PostGIS layer  
>> and a RASTER layer ?
>> I admit I have not done my homework and really examined the code  
>> for these two layers.
>
> John,
>
> It is currently possible to use a postgis table as a "tile index" for
> a raster layer.  To do so, configure the postgis table as a  
> distinct layer,
> and use the name of that layer in the TILEINDEX keyword of your  
> raster layer
> instead of the name of an external shapefile.
>
> The raster layer will do a spatial query on the tileindex table to get
> a list of rasters to plot.
>
> I'm a bit fuzzy on how you would do other sorts of query operations.
> It is possible a FILTER on the tileindex layer will be preserved as
> part of the tileindex query, but I'm not absolutely sure.  Of course,
> you could put complex query logic right into your DATA statement on
> the postgis layer.
>
> Best regards,
> -- 
> --------------------------------------- 
> +--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,  
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGeo, http:// 
> osgeo.org