hugin vingetting calculation

Asked by Sergei Delov

Hi,
The intent was to create distortion, tca and vingetting data in lensfun database format for DJI Mavic Pro Hasselblad L1D-20c.
tca is unnoticeable on this lens, but distortion/vingetting are really bad. Adobe Convert Raw reads vingetting data from exif; darktable can't.

I followed instructions from here: http://lensfun.sourceforge.net/calibration-tutorial/, though instructions use older hugin UI.

Results:

While distortion/tca look visually adequate, vingetting is not.

see:
https://filebin.net/k729qlyqaveqbnba/ImageVariables.png?t=7u9vjqqz
https://filebin.net/k729qlyqaveqbnba/Vingetting.png?t=vu2iof7o

I'm trying to understand what went wrong. One thing in tutorial is not clear - should I first calculate distortion and with distortion applied calculate vingetting?

I did it both ways, not much changed.

I used hugin 2018.0.0.5abfb4de7961

Regards,
Sergei.

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tmodes (tmodes) said :
#1

For vignetting optimization you need partially overlapping images, but no 100 % (or near 100 %) overlap.
The images need to be aligned (position and lens parameters) before vignetting calculation.

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Sergei Delov (sdelov) said :
#2

tmodes,
Thank you for the response.

I think I did everything you recommended, and still I gnerated wrong vignetting parameters.

Here are link to the .pto file, .dng and corresponding .tiff files (315mb):
https://drive.google.com/open?id=1LkXrNSoBE8PQKE0p0LXZLY4gFUXVyGn8

filebin.net has troubles with large files, here's the link to .pto/.dng files only (78mb):
https://filebin.net/k729qlyqaveqbnba/2.8.tar.xz?t=g4180kau

I used the following command to convert .dng files to tiff format with sensor's original linear RGB color space: "dcraw -4 -o 0 -M -T *.DNG"

That's what I see in darktable when I apply all lens corrections:
https://filebin.net/k729qlyqaveqbnba/DarkTableScreenCapture.png?t=g4180kau

I hope this info will keep you interested.

Regards,
Sergei.

Revision history for this message
tmodes (tmodes) said :
#3

Before calculating vignetting parameters you need to align the images before. When all images are on top of each other Hugin can't calculate the vignetting parameters.
The second issue: if you feed in linear images you need to specify this. Otherwise Hugin assumes gamma corrected images and the photometric optimizer goes haywire.

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