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Author Topic: parrot sequoia calibration  (Read 4466 times)

dowallin

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parrot sequoia calibration
« on: November 30, 2018, 02:48:21 AM »
Greetings. I am processing Parrot Sequoia multispectral imagery using the "Radiometric calibration using reflectance panels in PhotoScan Professional 1.4. I have images for the reflectance panel and I've located the panels as indicated in step 3 of this tutorial. I am using this calibration panel for the first time. This is the calibration panel that came with the camera. I don't have a "calibration certificate" that is mentioned in the tutorial. Not sure if one came with it or not. In the "Calibrate Reflectance" dialog box, it is showing a reflectance of 1 for each of the 4 bands. This seems unlikely.


Am I doing something wrong here? Where do I get the correct reflectance values?


Isn't another option to use data from the sun sensor and if so, how do I do this? I've brought in the tiff files that represent green, red, red edge and NIR, but not the jpg files that contain the 16MP RGB images. The folder also contains two .dat files (sequoia_diag.dat and sequoia_param.dat). Do these contain sun sensor info?


Any help would be much appreciated.


David

Alexey Pasumansky

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Re: parrot sequoia calibration
« Reply #1 on: November 30, 2018, 02:27:25 PM »
Hello David,

Currently PhotoScan supports automatic detection of the radiometric panels with MicaSense QR code. If you have a different panel and it is not recognized automatically, then you should manually move all the cameras containing the image of the panel to the newly created "Calibration images" folder in the Workspace pane, then mask everything outside the panel for each band of each camera in the folder, then input the reflectance values of the panel for each band and after that start the calibration procedure.
Best regards,
Alexey Pasumansky,
Agisoft LLC

dowallin

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Re: parrot sequoia calibration
« Reply #2 on: November 30, 2018, 08:14:04 PM »
Alexey,
Yes, I'm using the Micasense calibration panel with the QR code. Photoscan does recognize them. I had 3 sets of images (12 images total; for each set, there is one image for each of the 4 Parrot bands). In the "Calibration Reflectance" dialog, it only shows the 3 images for the green band. Not sure if it found the images for the other 3 bands?

And, note that it filled in reflectance values of 1 for each of the 4 bands. This seems unlikely but maybe it is correct?

Can you clarify?

And, what is the "Use sun sensor" checkbox and how would data from the sun sensor be accessed by Photoscan? I'm guessing that this might be in the two .dat files that I mentioned but not sure how to import these files into Photoscan. Can you explain this?

Thanks!
David

Alexey Pasumansky

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Re: parrot sequoia calibration
« Reply #3 on: November 30, 2018, 08:32:28 PM »
Hello David,

The information regarding the reflectance values for the panel haven't been found int he meta-data of the images, so you have to input them manually. They might be written on the panel itself, if not, then you can contact MicaSense for more information (https://www.micasense.com/prv/)

If you check on Sun Sensor option, PhotoScan will use the meta-information from the sunshine sensor of Sequoia (should be already embed to the images, so no external files are required).
Best regards,
Alexey Pasumansky,
Agisoft LLC

dowallin

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Re: parrot sequoia calibration
« Reply #4 on: December 01, 2018, 04:53:57 AM »
Alexey,
Great! Just the info I was looking for. Just out of curiosity, how can I see the info from the Sun Sensor? For any given image, if I go to "properties" in the image, I've scanned through the "details" tab, and the other tabs as well but I don't see anything that looks like it could be sun sensor data. And what are those two .dat files anyway?

David