The first thing we will do is transform our raster, since the MODIS rasters have their own unique spatial-reference system. We will convert the raster from MODIS Sinusoidal projection to US National Atlas Equal Area (SRID 2163).
Before we transform the raster, we will clip the MODIS raster with our San Francisco boundaries geometry. By clipping our raster before transformation, the operation takes less time than it does to transform and then clip the raster:
SELECT ST_Transform(ST_Clip(m.rast, ST_Transform(sf.geom, 96974)), 2163) FROM chp05.modis m CROSS JOIN chp05.sfpoly sf;
The following image shows the clipped MODIS raster with the San Francisco boundaries on top for comparison:
When we call ST_Transform() on the MODIS ...
