| Re: Conversion Factor [message #57214] |
Thu, 06 December 2007 04:21 |
devin.white
Messages: 50
Registered: March 2007
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Member |
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When you supply your radiance file to FLAASH, it prompts you to supply
scale factors as well. You can provide either a single value for all
bands or text file with an array of values (one for each band). To
convert from what you have to what you need, choose single value and
type "10". You don't need to mess with the scale factors stored in
the HDF--those are automatically applied by ENVI when you initially
open your file (they convert the stored integer data to radiance).
On Dec 5, 4:36 pm, Marsh...@gmu.edu wrote:
> Hi Guys:
>
> I have the following scale factors for 50 bands.
>
> "scale_factor"
> 0.10000000, 0.10000000, 0.10000000, 0.10000000, 0.10000000,
> 0.10000000,
> 0.10000000, 0.10000000, 0.10000000, 0.10000000, 0.01000000,
> 0.01000000,
> 0.01000000, 0.01000000, 0.01000000, 0.10000000, 0.01000000,
> 0.01000000,
> 0.01000000, 0.01000000, 0.01000000, 0.01000000, 0.01000000,
> 0.01000000,
> 0.01000000, 1.00000000, 0.00500000, 0.00600000, 0.00600000,
> 0.00600000,
> 0.00600000, 0.00600000, 0.00500000, 0.00100000, 0.00300000,
> 0.00600000,
> 0.00500000, 0.00500000, 0.00200000, 0.00100000, 0.00100000,
> 0.01000000,
> 0.01000000, 0.01000000, 0.01000000, 0.01000000, 0.01000000,
> 0.01000000,
> 0.01000000, 0.01000000
>
> FLAASH atmospheric correction software requires radiance to be in
> microwatts/centimeter^2/steradian/nanometer. Whereas, I have the
> radiance in watts/meter^2/steradian/micron. What shall I do?
>
> Best Regards,
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| Re: Conversion Factor [message #57242 is a reply to message #57214] |
Wed, 05 December 2007 15:49  |
Marshad2
Messages: 15
Registered: July 2007
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Junior Member |
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On Dec 5, 5:01 pm, Brian Larsen <balar...@gmail.com> wrote:
>> FLAASH atmospheric correction software requires radiance to be in
>> microwatts/centimeter^2/steradian/nanometer. Whereas, I have the
>> radiance in watts/meter^2/steradian/micron. What shall I do?
>
> just do the conversion...
>
> 1e6 microwatts in a watt
> 100^2 cm^2 in a m^2
> 1e3 nm in a micron
>
> so just take your data
>
> data = data / (1e6 * 100.^2 * 1e3)
> or
> data /= (1e6 * 100.^2 * 1e3)
>
> Might have to cast things to a double to be safe... but sure I got
> this right before you go too far with it...
>
> Cheers,
>
> Brian
>
> ------------------------------------------------------------ --------------
> Brian Larsen
> Boston University
> Center for Space Physics
Thank you guys. You all deserve appreciation.
Regards,
Arshad
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| Re: Conversion Factor [message #57271 is a reply to message #57242] |
Wed, 05 December 2007 14:01 |
Brian Larsen
Messages: 270
Registered: June 2006
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Senior Member |
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> FLAASH atmospheric correction software requires radiance to be in
> microwatts/centimeter^2/steradian/nanometer. Whereas, I have the
> radiance in watts/meter^2/steradian/micron. What shall I do?
just do the conversion...
1e6 microwatts in a watt
100^2 cm^2 in a m^2
1e3 nm in a micron
so just take your data
data = data / (1e6 * 100.^2 * 1e3)
or
data /= (1e6 * 100.^2 * 1e3)
Might have to cast things to a double to be safe... but sure I got
this right before you go too far with it...
Cheers,
Brian
------------------------------------------------------------ --------------
Brian Larsen
Boston University
Center for Space Physics
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| Re: Conversion Factor [message #57273 is a reply to message #57271] |
Wed, 05 December 2007 13:42 |
Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior Member |
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Marshad2@gmu.edu wrote:
> Hi Guys:
>
> I have the following scale factors for 50 bands.
>
> "scale_factor"
> 0.10000000, 0.10000000, 0.10000000, 0.10000000, 0.10000000,
> 0.10000000,
> 0.10000000, 0.10000000, 0.10000000, 0.10000000, 0.01000000,
> 0.01000000,
> 0.01000000, 0.01000000, 0.01000000, 0.10000000, 0.01000000,
> 0.01000000,
> 0.01000000, 0.01000000, 0.01000000, 0.01000000, 0.01000000,
> 0.01000000,
> 0.01000000, 1.00000000, 0.00500000, 0.00600000, 0.00600000,
> 0.00600000,
> 0.00600000, 0.00600000, 0.00500000, 0.00100000, 0.00300000,
> 0.00600000,
> 0.00500000, 0.00500000, 0.00200000, 0.00100000, 0.00100000,
> 0.01000000,
> 0.01000000, 0.01000000, 0.01000000, 0.01000000, 0.01000000,
> 0.01000000,
> 0.01000000, 0.01000000
>
> FLAASH atmospheric correction software requires radiance to be in
> microwatts/centimeter^2/steradian/nanometer. Whereas, I have the
> radiance in watts/meter^2/steradian/micron. What shall I do?
Umm... convert the values to the required units?
micro == 10^-6
centi == 10^-2
nano == 10^-9
and
micron == micrometer.
Add the exponents accordingly (don't forget the ^2 bits!) and multiply.
cheers,
paulv
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