Lens dirtortion of Movie Clip Editor


(brothermechanic) #1

Hi
I learn how to set true settings to K1, K2, and K3 lens parameters of Movie Clip Editor.
I know about open source library - lensfun http://developer.berlios.de/project/showfiles.php?group_id=9034
And for example
Single photo https://dl.dropboxusercontent.com/u/34973756/blender/IMG_1314.JPG
Canon 550D wint Canon EF-S 18-55mm f/3.5-5.6 III
There is scene https://dl.dropboxusercontent.com/u/34973756/blender/lens.zip
I set K1, K2, and K3 such as a=“0.00029” b="-0.00065" c="-0.04054" in lensfun’s /usr/share/lensfun/slr-canon.xml
But there is no right effect…
Why? May be this is don’t same settings?
(with gimp-lensfun plugin i get this https://dl.dropboxusercontent.com/u/34973756/blender/IMG_1314-gimp.JPG)


(bashi) #2

I think the Lensfun distortion model=“ptlens” you used the data from is not equal to the one used in Blender. I found this site where k1 k2 k3 show up, but not for this lens. No idea though how and if you can convert from one to another…


(brothermechanic) #3

>convert from one to another
i think so too
> I found this site where k1 k2 k3 show up
this is lensfun library i talk about

Thank you for answer, i will try to found value for convert abc to k1k2k3


(brothermechanic) #4

Hi.
It’s look like diffece of dist values (bledner and lensfun) don’t linear…
This is my experiment, where i try to match lens corrected image and source image.

https://dl.dropboxusercontent.com/u/34973756/blender/lens.blend


(ulairi) #5

We’re using third order polynomial radial distortion and second order tangential distortion model (even so tangential coefficients are not exposed to the interface). it doesn’t seem lensfun supports this model and you can not switch from one model to another one, you would need to re-calibrate your camera.

So it’s not possible to use that database to compensate distortion within blender. What you could do is to use a grid calibration application from opencv (they’re exactly the same distortion model) to calibrate your camera.


(brothermechanic) #6

Thank you!
I try with opencv.