Question

Splitting up a GeoTiff to evaluate cells colors

U

I need to evaluate the color of each individual cell of a geotiff. I splitted the geotiff into it's cells using the RasterTiler with CellSize 1,1 and it seems to work. I do now just need to access the color of each cell and to test for it. I tried to do it using the Tester, but it seems that it doesn't work.

3 replies

david_r
Rank
Userlevel 4

Try the RasterCellCoercer, it will output the cell values in the FME list "_band{}.value". Here's an old (but still relevant) article about it: https://knowledge.safe.com/articles/1281/rastercellcoercer-making-points-from-rasters.html

Just be aware that the RasterCellCoercer tends to be rather slow for large rasters. If it's too slow, consider going the point cloud route using the PointCloudCoercer, although I'm not sure if it lets you access the individual cell values.

takashi
Rank
Userlevel 2
Badge +17

Hi , depending on how you need to split the raster, the RasterExpressionEvaluator could also be an option.

U

Try the RasterCellCoercer, it will output the cell values in the FME list "_band{}.value". Here's an old (but still relevant) article about it: https://knowledge.safe.com/articles/1281/rastercellcoercer-making-points-from-rasters.html

Just be aware that the RasterCellCoercer tends to be rather slow for large rasters. If it's too slow, consider going the point cloud route using the PointCloudCoercer, although I'm not sure if it lets you access the individual cell values.

I've previously tried to find a solution, but I couldn't manage to access the color there as well. The "_band{}.value" made the clue. After that I had to normalize the value and to set the color of the polygons. That way I got polygons with the same color as before and managed to keep the geotiff representation.

Edit: If someone is interested in the way I've done it, below is the custom transformer I created as image.

geotiffcellsextractor.png

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