WMS does not work with two partially overlapping layers

[Bang Pham Huu]

If two WMS layers are overlaid from WMS clients but they don't intersect completely from grid domains, then rasql will show error, e.g:

sdom(BlueMarbleCov): [0:17999,0:8999]
sdom(Germany_2D_B04_10m): [0:5000,0:5000]

SELECT ENCODE( ( Scale( ( ( c1[5473:5972, 1145:1787] ) ), [0:255, 0:255] ) ) 

OVERLAY 

( Scale( ( ( c0[9984:10054, 1828:1898] ) ), [0:255, 0:255] ) ) , "png",

FROM BlueMarbleCov AS c0, Germany_2D_B04_10m AS c1

with error

Reason: The subset extent [5473:5972,1145:1787] extends outside the array extent [0:5000,0:5000]

It will need to enhance in WMS with:

• If a subset is within the collection's grid domain, use the current implementation.
• If a subset only intersects with the collection's grid domain, it needs to use extend, e.g:

rasql -q 'select extend(c[0:20,0:50], [0:255,0:255]) from BlueMarbleCov as c'

• If a subset is outside of collection's grid domain, then no need to create a null grid domains for this collection as it is not used.

[Bang Pham Huu]

This is a new feature actually in WMS which allows to return result from 2 layers in different domains.

[Bang Pham Huu]

WMS client can support this case by adding separated layers (the overlaying will be done by WMS client), e.g: with openlayers to request 2 different layers with different UTM zones:

              new ol.layer.Tile({
                source: new ol.source.TileWMS({
                    url: "http://localhost:8082/rasdaman/ows",
                    params: {'LAYERS': 'utm31_2d_wgs84,'}
                })
              }),

            new ol.layer.Tile({
                source: new ol.source.TileWMS({
                    url: "http://localhost:8082/rasdaman/ows",
                    params: {'LAYERS': 'utm32_2d_wgs84'}
                })
              })