How do I subtract two bands using HYDRA linear combination?
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wiweathergirl
- Posts: 3
- Joined: Thu Jan 29, 2009 7:38 pm
How do I subtract two bands using HYDRA linear combination?
How do I use the linear combination in HYDRA? All I see is a command prompt. I want to do band 27 minus band 31 and get an image out of this.
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jessica.braun
- Posts: 66
- Joined: Wed Jan 07, 2009 7:51 pm
Re: How do I subtract two bands using HYDRA linear combination?
There is help in the McIDAS-V User's Guide for the linear combination control:
http://www.ssec.wisc.edu/mcidas/doc/mcv ... ntrol.html
otherwise,
a = selector('27', 'red')
b = selector('31', 'green')
c = a - b
combine(c)
in the linear combination console will give you a red selector bar at channel 27, a green selector bar at channel 31, define the variable "c" as the subtraction expression, and create the new field.
The resulting field will show up in the Field Selector tab in the Fields tab, where you can then display the image.
If you are just doing a simple subtraction, you can also use the "4 channel combination" display type - this is the one that is similar to old HYDRA just for basic arithmetic expressions and utilizes pull down menus to create an expression.
http://www.ssec.wisc.edu/mcidas/doc/mcv ... ntrol.html
otherwise,
a = selector('27', 'red')
b = selector('31', 'green')
c = a - b
combine(c)
in the linear combination console will give you a red selector bar at channel 27, a green selector bar at channel 31, define the variable "c" as the subtraction expression, and create the new field.
The resulting field will show up in the Field Selector tab in the Fields tab, where you can then display the image.
If you are just doing a simple subtraction, you can also use the "4 channel combination" display type - this is the one that is similar to old HYDRA just for basic arithmetic expressions and utilizes pull down menus to create an expression.