[GRASS-user] Chavez COST Model

GRASS GRASS user
1

hellow,

I’ve download S.M. Skirving’s algorith for atmospheric correction of Landsat imaged based on Chavez’s COST-Model, from the following web:
http://arsc.arid.arizona.edu/resources/image_processing/landsat/ls5-atmo.html

the algorithm is:

MODEL GMD = (( -2.8890805 + (0.0602353 * ‘name_of_the_band’ - 0.15)) * PI *0.9932554 ** 2) / (195.7 * COS (PI/180 * (90 - 52.21)) ** 2)

The results obtained with r.map.calc represent the reflectiviy of each pixel and range between 0-1, but really what I want to get is the image with the Digital Levels corrected (from the raw image)with values 0-255 to afterwards perform a supervised classification.

How must I do to get it?

thanks in advanced

Gabriella.

2

2006/7/3, Gabriela Messner <gabmessner@gmail.com>:

The results obtained with r.map.calc represent the reflectiviy of each
pixel and range between 0-1, but really what I want to get is the image with
the Digital Levels corrected (from the raw image)with values 0-255 to
afterwards perform a supervised classification.

Multiply by 255 and truncate to integer ??

just a wild guess.
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