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Author Topic: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files  (Read 3220 times)

Nikos_geography

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RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« on: January 08, 2018, 07:25:30 PM »
Hello,

I want to radiometric calibrate a set of MS images acquired by a parrot sequoia camera. I have the calibration target and 2 .dat files. I have 2 questions.
Firstly, do I need to use them both for the radiometric calibration procedure?
If yes, how can I import the .dat files?
I am using PS version 1.4.0.


Thank you.

Alexey Pasumansky

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Re: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« Reply #1 on: January 08, 2018, 07:38:22 PM »
Hello Nikos_geography,

Can you provide an example of such dat file?
Best regards,
Alexey Pasumansky,
Agisoft LLC

Nikos_geography

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Re: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« Reply #2 on: January 08, 2018, 10:53:28 PM »
These are the .dat files which had been created with the use of the drone.

Alexey Pasumansky

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Re: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« Reply #3 on: January 12, 2018, 12:52:12 PM »
Hello Nikos_geography,

It seems that this information is only some kind of auxiliary data for debugging purposes. Generally, meta-data included to the images from Sequoia would be sufficient. However, you need also to know the reflectance values for the calibration panel.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Nikos_geography

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Re: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« Reply #4 on: January 13, 2018, 12:59:05 PM »
Thank you for your reply.

I have made the radiometric calibration by using the calibration targets. The sensitivity has changed. The values are no longer DN (for example the Sensitivity has chenged from 70 to 0.005).

But my cloud points is white. I think that I have to "update" or something the values in the histogram so I can get a grey scale image again.

Do you have any idea?

Nikos_geography

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Re: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« Reply #5 on: January 14, 2018, 05:15:56 PM »
I found it!

I simply saved the project, I closed the program and I have re-opened it again.


Problem solved!

jsal490

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Re: RADIOMETRIC CALIBRATION OF MS IMAGES USING .dat files
« Reply #6 on: January 16, 2018, 06:43:48 PM »
Thank you for your reply.

I have made the radiometric calibration by using the calibration targets. The sensitivity has changed. The values are no longer DN (for example the Sensitivity has chenged from 70 to 0.005).

But my cloud points is white. I think that I have to "update" or something the values in the histogram so I can get a grey scale image again.

Do you have any idea?

Hello Nikos,

Would you be willing to elaborate on what steps you took to get the sensitivity values to change? Also, do they match a particular field in the images meta-data? In the meta-data for my images (i use Exif Tag to view the metadata) I see a field labled 'spectral sensitivity' but it simply is a whole number that corresponds to the wavelength's midpoint for the particular sensor (e.g., for a green calibration panel image the number in the metadata is 550 nm for the spectral sensitivity.

Thanks for your help.