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Question

raster cell calculations based on coordinates

  • July 25, 2013
  • 3 replies
  • 91 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.
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3 replies

takashi
Celebrity
  • takashiCelebrity
  • July 25, 2013
Hi,

 

 

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

 

 

Takashi
Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
M
  • mvw
  • Author
  • July 25, 2013
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
Celebrity
  • takashiCelebrity
  • July 25, 2013
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?
Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?

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