Compare all point to raster snow depths

[micahjohnson150]

HP would like a comparison of all 30K point depth measurements to the the QSI - USGS rasters and QSI - ASO rasters.

All points should be compared (across all dates) to the first flights (QSI 1) and then all points to the second flight (QSI 2).

The simplest way we can do this is to use ST_Value which simply grabs the near pixel. In the other snow depth comparison we make an effort to recast/shape the rasters to a common grid and resolution for matrix math.