[Bf-vfx] Blender camera tracking approach

[Tobias Kummer]

After some more tinkering, I came up with the following revised proposal:
http://www.pasteall.org/pic/12084

This takes some of your (Remos) concerns into account.

Regards,

Tobi

On 05/08/2011 10:09 PM, Remo Pini wrote:
> Hm... I have never noticed the slight distortions to cause issues with
> the tracker... might be a question of the implementation, but I don't
> see, why the material would have to be converted twice, even IF
> "undistorting" is required...
>
> (1) take original footage
> (2) undistort to track (temporary copy)
> (3) track
> (4) distort tracking data according to undistort
> (5) use original footage + track data + lensinfo from source (or
> undistort function)
>
> Syntheyes seems to do that under the hood, I guess, never seen tracking
> issues due to distortions...
>
>
>> -----Original Message-----
>> From: bf-vfx-bounces at blender.org [mailto:bf-vfx-bounces at blender.org]
>> On Behalf Of Tom M
>> Sent: Sonntag, 8. Mai 2011 8:20
>> To: Blender motion tracking&  VFX
>> Subject: Re: [Bf-vfx] Blender camera tracking approach
>>
>> On Sun, May 8, 2011 at 10:06 AM, Remo Pini<remo.pini at avexys.com>
>> wrote:
>>> I kind of disagree...
>>>
>>> If you have lens distortion in you footage, this would most likely
> be
>>> bad and you would not want the final result to have that in it
> anymore,
>>> sooo....
>> You are thinking extreme distortion - this is about the very slight
>> distortion that comes from all camera lenses due to their lense shape
>> (as well as lense imperfections - but the imperfections are mostly
>> ignored by most lense solvers).
>>
>> Our brains ignore the distortion but it confuses trackers since travel
>> in a straight line isn't straight with the distortion.
>>
>> Undistorting the lense reduces the image quality because it shifts
>> pixel locations and thus 'blurs' pixels that the undistorted location
>> of a pixel will not be exactly on the pixel boundary of a previous
>> pixel.
>>
>> Thus undistortion is only used to provide straighter lines to the
> tracker.
>> Applying the lens distortion to your rendered image is so that it's
>> straight lines are curved similarly to that of the original image.
>> Again this introduces blurring of your render if it is applied as a
>> post process - so either you need to render larger or do the
>> distortion at render time.  In practice the amount of bluring from
>> doing it as a post process is probably not significant enough to be
>> noticable in most situations.
>>
>> LetterRip
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