Generating band ratio with Model Maker

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Generating band ratio with Model Maker
By Nicolas in ERDAS Software Forum

Hi, I'd like to find out how to generate band ratios using ERDAS scripting and Model Maker. Basically, I'd like to create a new channel for a radar image and store in it the result of computations on other existing channels so that I can generate different composites. Did anyone write something similar already? Thank you.

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Re: Generating band ratio with Model Maker
By Donn Rodekohr in ERDAS Software Forum

Nicolas,

Band ratioing within Model Maker is easy -- just translate the ratio formula to a modeler syntax.  For example, if the ratio is a simple (Band 4/Band 5), the spatial modeler syntax would be

$n1_image(4) / $n1_image(5)

where the input file is named "image" and it has at least 5 bands.

Integrating the product of that ratio into the source file is also easy with a second step taking the product of the ratio program and integrating it with a STACKLAYER command.  Here is how I would set up this model --

Input file:  $n1_radar.img         -- this is a 5 band image

Ratio function:  $n1_image(4) / $n1_image(5)

Output of this function:  A temporary raster $n3_temp

2nd Function circle:  both $n1_radar and $n3_temp are connected to this function

   STACKLAYER ($n1_radar(1), $n1_radar(2), $n1_radar(3), $n1_radar(4), $n3_temp, $n1_radar(5))

Final Output file:  $n5_radar_rats.img       -- this file has the same data format as the input radar image.

 

The final output file MUST be a different file name than the input file.  

Does this help?

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