Question

raster cell calculations based on coordinates

  • 25 July 2013
  • 3 replies
  • 2 views
M
I'd like to perform a calculation on the z values of a raster. I haven't found any transformers that let me roll the column number into the calculation. My z value recalculation wants to use the number of pixels or cells east ofthe origin as a variable.

 

 

Why? I'm trying to modify a thermal image in which the values read late in the day, in the east, are much higher than those collected earlier in the day. So I'm trying to create a correction surface, if you will, that conpensates for time (and therefore temperature).

 

 

Thanks.

3 replies

takashi
Rank
Userlevel 2
Badge +17
Hi,

 

 

The RasterCellCoercer adds column and row index to output features if you specify explicitely "Column Attribute" and "Row Attribute" parameters.

 

 

Takashi
M
Many thanks, Takashi, but I don't think going to vector is the way to do it, is it? After 5 minutes, it has only managed to get thruogh 1.5% of intermediate processing. Little wonder since I'm dealing with a raster of 738,480,000 cells!

 

 

There are transformers that allow calculations on cells but none (that I've found!) seem to allow incorporating the row or column number.

 

 

TIA.
takashi
Rank
Userlevel 2
Badge +17
The RasterCellCoercer tends to consume much time, but there aren't other transformers to relate with column/row number as far as I know. Using a RasterPropertiesExtractor, we can get the geometric raster properties (e.g. origin coordinates, number of rows / columns, extents etc.). Those properties can be used to calculate required values?

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