[Bf-vfx] Non-square shapes for pattern and search areas

[François T.]

@julien : they can be useful in some cases yes, especially for 2.5D
tracking, corner pin, Roto,.... check out what people do with it (
http://www.imagineersystems.com) To be honest, it wouldnt be my priority at
least for matchmoe, but it is a very powerful tool, so at some point if you
guys feel like it sure why not ;-)
I personaly use it for all corner pin stuff. (The tutorial Sebastian did ?
it's 10 times easier and faster with planar tracking) and for removal object
as well, but not for matchmove purposes

@Keir : found an example just right now of a case where I add to use
rectangular pattern w/o any chance to do otherwise *(Of course I cannot
share the footage with you, so you'll have to trust me on that one, or make
the test yourself :) )*
LED + motion blur. They used LED as markers on set. With motion blur the LED
becomes a strip but for a start the pattern has to be as small as the LED
otherwise you will get jittering. but when you get motion blur, the LED gets
wider and the pattern needs to stay at the center of this strip be correct,
so if the pattern is not wider than the blur LED, the marker will drift. And
if you keep it square it might become a big pattern where the LED brightness
is so little compare to the all rest, that the tracker won't care too much
about LED anymore but mostly about what does surround it, which result also
as drift

hope you got it :p

cheers
F.

2011/7/21 julien michot <julien.michot.fr at gmail.com>

> This is not *yet* a planar tracker!
>
> What do you think about planar trackers, are they more efficient or easier
> to use?
> Would it be useful to implement one in libmv?
>
> -julien
>
>
> On Wed, Jul 20, 2011 at 10:28 PM, François T. <francoistarlier at gmail.com>wrote:
>
>> I don't know why you would need that. This is not planar tracking, so it
>> really doesn't matter at the end.
>>
>> F.
>>
>> 2011/7/20 Sergey I. Sharybin <g.ulairi at gmail.com>
>>
>>>  Hi everyone!
>>>
>>> It was got discussion today in #lbmv at irc.freenode.net related on
>>> forcing pattern/search area be square.
>>>
>>> Main question: is non-square shape of marker useful in motion tracking
>>> workflow?
>>>
>>> Some quick cases i could think could be solved just adding offset to
>>> search area or by resizing this areas.  But we've checked some tracking
>>> applications and they allow to use non-square markers. So i'm not sure
>>> it'll be good idea to stick to squares.
>>>
>>> P.S. From UI point of view, search are could be rectangular, just
>>> "missing" areas could be filled with black when it's passing to libmv which
>>> would probably be optimized for squares.
>>>
>>> --
>>> With best regards, Sergey I. Sharybin
>>>
>>>
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>>>
>>
>>
>> --
>> ____________________
>> François Tarlier
>> www.francois-tarlier.com
>> www.linkedin.com/in/francoistarlier
>>
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>>
>
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-- 
____________________
François Tarlier
www.francois-tarlier.com
www.linkedin.com/in/francoistarlier
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