Hi all!

Got a serious problem with distortion here. I have a 2.35 footage (=> pixel 
aspect ratio of 2.0), and I need to undistort the images for a matchmoving 
process on SynthEyes. I therefore use NukeX and its LensDistortion plugin. The 
issue is, whatever the undistort method we use (Image analysis, Grid analysis, 
Line analysis or even STmaps), there remains some sort of distortion on the 
lateral edges of the image. Curved lines of the original footage are indeed 
corrected, they're now horizontal or vertical, but the more you reach the left 
or right side of the image, the more this image is stretched horizontally. You 
can clearly see this if you put a 2D tracker on a feature and stabilize the 
image around it: when for example the tracker moves to the left, the image 
appears to stretch horizontally till it reaches the extreme left border of the 
image.

I then tried something else: I activated the distortion autocalculation in 
SynthEyes. Thanks to this, the whole shot was solved perfectly. SynthEyes found 
an extra distortion value and corrected it.

My question is: how is it possible that SynthEyes finds this extra distortion 
value and NukeX not? I'd like to find a way to calculate the distortion in Nuke 
itself, because we later need to re-distort the 3D images to match the live 
footage, and we therefore need to re-use the same value that allowed us to 
undistort; as a result, I don't want to use both softwares to manage distortion 
issues.

Does this come from the aspect ratio of the image? (this is the first time I 
work on such an image format). Or am I doing something wrong? As I mentionned 
it, whatever the method I use in the LensDistortion plugin, it gives me the 
same wrong result...

Thanks!



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