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Gist 1447684

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Aandrewxhill
Last edited Dec 8, 2011
Created on Dec 8, 2011

This visualization shows a clipped portion of a Mars elevation raster dataset, rendering it as a base64-encoded PNG image for a defined geographic region. The SQL code uses PostGIS functions including `ST_AsPng`, `ST_Resample`, and `ST_ClipEx` to extract and resample the raster, while `ST_World2RasterCoordX` and `ST_World2RasterCoordY` convert real-world coordinates to raster grid positions. A multipolygon defines the area of interest, which is also converted to a raster grid via `ST_AsRaster` for alignment. The query filters rows with `St_Intersects` to return only relevant raster tiles, demonstrating spatial clipping and coordinate transformation for remote-sensing data delivery.

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