Version 7 (modified by mggr, 12 years ago) (diff)

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ATM

Consists of three files patterned as azYYMMDD[ABC].cal, where the last character before the .cal is A for scan speed 12.5, B = 25, C = 50.

The contents of the files are like:

AZ16 bandpairs 10 1 1000 az060306A.cal
87.72727273 24498 6.12019233 24468 2.31661442 24425 5.34458259 24501 2.05878963 24516 2.24453694 24704 1.29384497 24663 3.35342640 24280 0.64997509 24088 0.15410141 24283

Format appears to be 10 pairs of numbers specifying min and max sensor value for that band?

ATM calibration procedure

(as described by Andrew Wilson and dodgily transcribed by Mike)

  1. The ATM is placed in the light bench kept at Kidlington.
  2. The ATM is run for 500-1000 scans at the 12.5, 25 and 50 scan speeds with the light off (gets dark current values).
  3. The light is then switched on and left to warm up for 3-4hrs.
  4. Another set of captures is then made with the light on.
  5. These data are then processed into level 1 HDFs (without calibration being applied!) to get raw sensor values.
  6. For each channel (1-10)
    1. Using some smoothing, find the brightest columns in the image (this will be near the centre point and will be where the ATM scan head is closest to perpendicular to the light source.
    2. Take the average of the column to get the typical value (mode best for dark current, mean best for lit value)
  7. For channel 11, do nothing?

For channels 9 and 10 (SW IR), there is a fudge factor - apparently the ATM instrument records lower values when in the air than on the ground. One should process a flight line to get some idea of these, but the dark current is normally ~100-300 lower when flying. does this apply to the max value too?


Specim

Calibration files are produced by Specim when they do maintenance on the instrument.

Eagle

Files look like:

SN100022_130207_XB.cfg
Lens configuration file - contains calibration date and a few other human-readable items
SN100022_130207_XB.hdr
Header file for the data file..
SN100022_130207_XB.cal
Data file (containing several frames?) of the per-pixel calibrations

Hawk

SN300011_150207_NUC1.cfg
Lens configuration file - contains calibration date and a few other human-readable items
SN300011_150207_NUC1.hdr
Header file for the data file..
SN300011_150207_NUC1.cal
Data file (containing several frames?) of the per-pixel calibrations
SN300011_150207_NUC1.bad
Bad pixel table (text format, unsure of contents)

CASI

Radiometric calibration done by <name of guy> at Environment Agency (or Met Office?) using an integrating sphere at FSF and post-processing at the EA?

Consists of five 700KB files named inXXaA.rad, where X = two digit calibration sequence (up to 36 for 2007) and A = aperature (1-5). The files are binary (guessing pixel array of min/max floats?).

Additionally, there is a file that describes the view angles for each pixel to compensate for (lens?) distortions in the view field. The current version of this file is named NERC253_527tan.txt and looks like:

0 26.311677 0.051465
1 26.221749 0.089928
2 26.131682 0.090067
3 26.041477 0.090205
4 25.951133 0.090344
5 25.860650 0.090483
6 25.770029 0.090621
7 25.679270 0.090759
8 25.588372 0.090898
9 25.497337 0.091036
...
504 -26.131682 0.090205
505 -26.221749 0.090067
506 -26.311677 0.089928
507 -26.401465 0.089789
508 -26.491115 0.089649
509 -26.580625 0.089510
510 -26.669996 0.089371
511 -26.759227 0.089231

I'm guessing CCD column number, X angle, Y angle.