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optimization; which point falls into a polygon
| optimization; which point falls into a polygon [message #68036] |
Tue, 22 September 2009 14:57 |
Klemen
Messages: 80
Registered: July 2009
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Hi,
I am working with geostationary satellite data and some GIS rasters.
The satellite data do not have a regular sampling (pixel has a form of
a parallelogram) but I know corner coordinates of each pixels.
I would like to do some kind of spatial join - I would like to know
which of my pixels in GIS rasters (regularly sampled) fall into each
satellite pixel – I would like to create a raster where each GIS pixel
contains an index of the corresponding satellite index. This can be
easily done using 4 for loops when the GIS raster is small. However, I
would like to do this on a 1000 * 1000 large GIS layer. Satellite data
have factor 3 less pixels in one direction and factor 6 less pixels in
the other direction. Such a way is then really time consuming.
How to do it faster? I was reading of triangulation, but this would
probably mean that I would have to triangulate each GIS raster point
with satellite centre points and then check in which of four closest
satellite pixels falls the raster pixel. But I can imagine, that
building a triangulation for a million times is also not really fast.
Does anybody have a suggestion?
Thank you in advance!
Klemen
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