FIX - scale on 3D base coverage with pyramid returns wrong result if expression specified in LET clause

[Bang Pham Huu]

For example this WCPS query:

for $co in (air_quality_monitoring_data_co)

let $sub := [ansi(153403), X(147522.21879115:351672.21879115004083), Y(2422004.7731021:2799154.7731021)],
    $bands := ( ($co[ $sub ] - min($co[ $sub ])) / (max($co[ $sub ]) - min($co[ $sub ])) ) * 255 
return encode(
         scale(
           (unsigned char) ($bands),
           { 
             X:"CRS:1"(0:600), Y:"CRS:1"(0:700)
           } 
        ),   
       "png"
)

return wrong grid domains 0:3,0:600,0:700

SELECT encode((char)  ( SCALE(c_0, [0:3,0:600,0:700]) ) , "png" , "{\"geoReference\":{\"crs\":\"EPSG:3826\",\"bbox\":{\"xmin\":147522.21879115,\"ymin\":2422004.7731021,\"xmax\":351672.21879115004083,\"ymax\":2799154.7731021}},\"nodata\":[-3.4028234663852886E38]}")  FROM air_quality_monitoring_data_co_4 AS c_0

But without LET clause, this works fine, e.g.

for $co in (air_quality_monitoring_data_co)

return encode(
         scale( $co[ansi(153403), X(147522.21879115:351672.21879115004083), Y(2422004.7731021:2799154.7731021)]
               - min($co[ansi(153403), X(147522.21879115:351672.21879115004083), Y(2422004.7731021:2799154.7731021)])
                , { 
             X:"CRS:1"(0:20), Y:"CRS:1"(0:30)
           } ),  
       "png"
)

returns rasql query:

SELECT encode(SCALE(c_0[0,0:510,0:942] -  min_cells(c_0[0,0:510,0:942]) , [0:20,0:30]), "png" , "{\"geoReference\":{\"crs\":\"EPSG:3826\",\"bbox\":{\"xmin\":147522.21879115,\"ymin\":2422004.7731020999733,\"xmax\":351672.2187911500274,\"ymax\":2799154.7731021}},\"nodata\":[-3.4028234663852886E38]}")  FROM air_quality_monitoring_data_co_8 AS c_0