| 23 Jul 2014 06:34 AM |
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Hello Guys,
this is Vera from Germany!
I feel like an absolute beginner with ENVI and there are several problems I have with Opening Landsat (TM and ETM) Metadata Files with ENVI.
My Goal is to send the file through calibration processing. Program used: ENVI 4.7.; Image is Landsat 7 ETM+.
My proceeding:
I downloaded a Level 1 Landsat Data File (27 Feb 2000), unzipped it etc.
The unzipped file is this (copied from metadata.txt):
FILE_NAME_BAND_1 = "LE71940252000058EDC00_B1.TIF"
FILE_NAME_BAND_2 = "LE71940252000058EDC00_B2.TIF"
FILE_NAME_BAND_3 = "LE71940252000058EDC00_B3.TIF"
FILE_NAME_BAND_4 = "LE71940252000058EDC00_B4.TIF"
FILE_NAME_BAND_5 = "LE71940252000058EDC00_B5.TIF"
FILE_NAME_BAND_6_VCID_1 = "LE71940252000058EDC00_B6_VCID_1.TIF"
FILE_NAME_BAND_6_VCID_2 = "LE71940252000058EDC00_B6_VCID_2.TIF"
FILE_NAME_BAND_7 = "LE71940252000058EDC00_B7.TIF"
FILE_NAME_BAND_8 = "LE71940252000058EDC00_B8.TIF"
GROUND_CONTROL_POINT_FILE_NAME = "LE71940252000058EDC00_GCP.txt"
METADATA_FILE_NAME = "LE71940252000058EDC00_MTL.txt"
CPF_NAME = "L7CPF20000101_20000331.17"
I want to open the file via -> open external file -> Landsat -> Geo TIFF with Metadata
Then an error warning appears which says "This file does not appear to be a valid METADATA file."
There is my end of possible reasoning and I hope for help from People who have more notion!
I believe that one of the problems could be that the bands are all separate files(???).
So how can I do a calibration of the Image?
I'm thankful for an answer. Regards!
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Deleted User
New Member
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| 23 Jul 2014 07:06 AM |
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I now read that the Landsat Data TM and ETM+ are already calibrated to each other.
Does that mean there's no Need for calibration and furthermore, is this valid for all data that can be downloaded from the Landsat Archive in earthexplorer ? Thanks for Responses!
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MariM
Veteran Member
Posts:2396 
| 23 Jul 2014 08:00 AM |
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Most of the Landsat archive is orthorectified but you still need to apply the calibration coefficients to get to radiance or TOA reflectance. Unfortunately, the format for Landsat has changed since ENVI 4.7 so this version is unlikely to recognize the files properly. You can still calibrate the data but you will have to calibrate each band separately as TIFF files. The metadata contains all the information you need to enter into the Landsat calibration tool. If you can upgrade to the latest version of ENVI, it would be much easier.
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Deleted User
New Member
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| 01 Aug 2014 03:04 AM |
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Thanks for the answer! Calibrating the images works more or less now:)
I have another question on the values for Gain Bias.
I can't find the values for the Gain-Bias. It says "CPF" when looking up the values for Gain-Bias.
-> CORRECTION_GAIN_BAND_3 = "CPF"
CORRECTION_BIAS_BAND_3 = "CPF"
So I looked up the CPF (10Oct1990) on usgs.com. Again, none of the values found on the CPF list matched the ones that were automatically produced with the Landsat Calibration tool. Which values should I take from the CPF-list?
I would be very thankful for another reply on this!
Regards, Vera
PS: I hope I won't have another question!
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Deleted User
New Member
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| 04 Aug 2014 03:10 AM |
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Is there an answer?
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MariM
Veteran Member
Posts:2396
| 04 Aug 2014 05:59 AM |
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For Landsat TM/ETM, there should be something like the following in the metadata:
GROUP = MIN_MAX_RADIANCE
LMAX_BAND1 = 193.000
LMIN_BAND1 = -1.520
LMAX_BAND2 = 365.000
LMIN_BAND2 = -2.840
In ENVI 4.7, I believe you can enter these values into the dialog. The default values ENVI uses come from hard-coded values that are likely not correct for newer data coming from the USGS.
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Deleted User
New Member
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| 11 Aug 2014 09:19 AM |
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Thank you, but that wasn't exactly my question. I was asking for the Gain-Bias values. They're already in the dialog field, but I cannot say if they're correct or not because I can't find those values not in the MTL-File nor in the CPF's of the relevant year. Can you help me with this? Regards, Vera
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MariM
Veteran Member
Posts:2396
| 11 Aug 2014 01:23 PM |
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Sorry I can't remember what the ENVI 4.7 dialog looked like. We had in a service pack and ENVI 4.8 updated the dialog to read the LMIN/LMAX values. Previously, all of the calibration parameters were hard-coded I believe so that might be what you are seeing. The values will be based on the date of processing. I would highly suggest using an updated version of ENVI for calibrating landsat or perform a manual calculation using the values in the metadata.
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Deleted User
New Member
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| 12 Aug 2014 06:10 AM |
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Okay, thank you!
PS: Does anyone else have a notion?
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Lisbeth Herrera
New Member
Posts:1
| 19 Feb 2021 02:24 PM |
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Hello, I came for the same information (Calibration). I have experienced working with Landsat 8 OLI TIRS, I wanted to perform an analysis with Landsat ETM+ but I am not sure if the calibtration process is the same? Would someone give me an orientation, please?
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