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AVHRR Calibration and Georeferencing [message #44248]

Fri, 03 June 2005 07:13

vinit11
Messages: 1
Registered: June 2005

Junior Member

June 3, 2005

Hi,

I have an AVHRR file that I want to first calibrate and then georeference
using IDL (and ENVI).

Thanks to the 'envi_avhrr_calibrate_doit' I can input an AVHRR file and
get it calibrated. The output of this function is a file of type ENVI.

Now, there is also an 'envi_avhrr_geometry_doit' function that does what
georeferencing is needed, however, the input file to that function must be
of type AVHRR.

The problem I'm facing is that I cannot input the file that I calibrate
using the 'envi_avhrr_calibrate_doit' function (since it is of type ENVI
and needs to be of type AVHRR).

I'd be grateful if someone could help me come up with a solution to this
problem.

Thanks very much,

Vinit

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Re: AVHRR Calibration and Georeferencing [message #44345 is a reply to message #44248]

Fri, 03 June 2005 12:12

Jeff N.
Messages: 120
Registered: April 2005

Senior Member

I don't know anything about AVHRR processing, but couldn't you
georeference before you calibrate? I took a quick look at the geometry
doit, and it seems like it just computes some output bands that you'd
use to do the georeferencing with, without actually changing the
original level 1b image file. So it seems to me you could call the
georeferencing doit, then calibrate the input file, then georeference
the resulting calibrated image with the output bands of the
georeferencing routine.

Jeff

vinit11 wrote:
> June 3, 2005
>
> Hi,
>
> I have an AVHRR file that I want to first calibrate and then georeference
> using IDL (and ENVI).
>
> Thanks to the 'envi_avhrr_calibrate_doit' I can input an AVHRR file and
> get it calibrated. The output of this function is a file of type ENVI.
>
> Now, there is also an 'envi_avhrr_geometry_doit' function that does what
> georeferencing is needed, however, the input file to that function must be
> of type AVHRR.
>
> The problem I'm facing is that I cannot input the file that I calibrate
> using the 'envi_avhrr_calibrate_doit' function (since it is of type ENVI
> and needs to be of type AVHRR).
>
> I'd be grateful if someone could help me come up with a solution to this
> problem.
>
> Thanks very much,
>
> Vinit

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Re: AVHRR Calibration and Georeferencing [message #44354 is a reply to message #44248]

Sat, 11 June 2005 00:36

vinesh
Messages: 5
Registered: May 2005

Junior Member

Hi Vinit,

I have done ealborated work on AVHRR in IDL. Have u tried IDL. Please
send me the full problem and requirement in details

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Re: AVHRR Calibration and Georeferencing [message #44385 is a reply to message #44248]

Thu, 09 June 2005 06:45

vinit
Messages: 7
Registered: March 2005

Junior Member

June 9, 2005

Hi Jeff,

I tried georeferencing the original AVHRR file first using the
'envi_avhrr_geometry_doit' function. The problem is that the processed
file is of type ENVI. (I wrote a small program to test the type of the
output file). So I assume that the 'envi_avhrr_geometry_doit' function
changes the file (from AVHRR to ENVI) after processing by default.
Maybe there is a way to circumvent this problem but I don't know enough
to make that call. The 'envi_avhrr_calibrate_doit' function specifially
requires an input file of type AVHRR - so it doesn't process the
georeferenced file. In short, I'm back to square one.

Any suggestions or help would be much appreciated.

Thanks,

Vinit

P.S: I'm a programmer - so I don't know anything about AVHRR processing
too! :-)

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Re: AVHRR Calibration and Georeferencing [message #44387 is a reply to message #44345]

Thu, 09 June 2005 06:07

vinit
Messages: 7
Registered: March 2005

Junior Member

June 9, 2005

Hi Jeff,

Thanks very much for your reply. Sorry for the delay in getting back to
you though. I will try out your suggestion and see if that works.

Thanks,

Vinit

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Re: AVHRR Calibration and Georeferencing [message #44431 is a reply to message #44354]

Mon, 13 June 2005 18:20

vinit
Messages: 7
Registered: March 2005

Junior Member

July 13, 2005

Hi Vinesh,

Sorry for the late reply.

Thanks for your offer to help me out. I finally figured out the problem
though.

To answer your question: yes, I am indeed programming in IDL.

Thanks very much,

Vinit

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Re: AVHRR Calibration and Georeferencing [message #69172 is a reply to message #44248]

Sat, 19 December 2009 12:10

Robert Moss, PhD
Messages: 29
Registered: November 2006

Junior Member

On Dec 19, 5:20 am, Susanne Adams <adams.susa...@googlemail.com>
wrote:
> Hi,
>
> I have an AVHRR file that I want to first calibrate and then
> georeference
> using IDL (and ENVI).
>
> Thanks to the 'envi_avhrr_calibrate_doit' I can input an AVHRR file
> and
> get it calibrated. The output of this function is a file of type ENVI.
>
> Now, there is also an 'envi_avhrr_geometry_doit' function that does
> what
> georeferencing is needed, however, the input file to that function
> must be
> of type AVHRR.
>
> The problem I'm facing is that I cannot input the file that I
> calibrate
> using the 'envi_avhrr_calibrate_doit' function (since it is of type
> ENVI
> and needs to be of type AVHRR).
>
> I'd be grateful if someone could help me come up with a solution to
> this
> problem.
>
> Susi

envi_avhrr_geometry_doit does not actually georeference the input
file. You would use envi_avhrr_warp_doit for that purpose. You should
probably read the documentation more carefully. Put ENVI_AVHRR* in the
search and read about the routines that pop up

r

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