Hi Michael. I had a look at the planar tracker but as far as I can tell,
that node creates a cornerpin based on the matrix that it calculates, but as
far as I can see there is no way in that you can feed the planar tracker
cornerpin data and have it calculate the corresponding Matrix. I think
nuke.math.Matrix4 is the way.

Pete

On Tue, Aug 23, 2011 at 3:30 AM, Michael Garrett <[email protected]>wrote:

> I haven't got 6.3 in front of me but does the PlanarTracker add anything
> into the mix to make this easier?  I seem to remember it outputs a 4*4
> matrix for the planar track which is essentially a corner pin but I'll admit
> I need to look more closely at it.
>
>
> On 21 August 2011 23:40, Pete O'Connell <[email protected]> wrote:
>
>> Thanks a lot Ivan. I'll have a play around with that tonight.
>>
>> Cheers
>> Pete
>>
>>
>> On Mon, Aug 22, 2011 at 3:57 PM, Ivan Busquets <[email protected]>wrote:
>>
>>> Hi Pete,
>>>
>>> It's very possible, but probably easier to do it in Python than using
>>> expression-links. Have a look at the nuke.math.Matrix4 class, and its
>>> mapUnitSquareToQuad() method.
>>>
>>> I have a function somewhere to feed the transformation of a CornerPin
>>> node into the "matrix" knob of a roto/rotopaint node that would
>>> probably fit the bill for this too. I can try to dig that up if you're
>>> interested, but it would roughly consist of the following steps:
>>>
>>> 1 - Get the coordinates of the 4 "TO" corners from your cornerpin node.
>>> 2 - Build a "TO" matrix using mapUnitSquareToQuad(to0.x, to0.y, to1.x,
>>> to1.y, ...)
>>> 3 - Get the coordinates of the 4 "FROM" corners from your cornerpin node.
>>> 4 - Build a "FROM" matrix using mapUnitSquareToQuad(from0.x, from0.y,
>>> from1.x, from1.y, ...)
>>> 5 - The final transformation matrix should be =>  to_matrix *
>>> from_matrix.inverse().
>>>
>>> Then you can use that to fill in the matrix knob in a gridwarp, a roto
>>> node, etc.
>>>
>>> Not the best example, but if you want some more info on how to use
>>> nuke.math.Matrix4.mapUnitSquareToQuad(), have a look here (towards the
>>> end of the page).
>>>
>>>
>>> http://www.nukepedia.com/written-tutorials/using-the-nukemath-python-module-to-do-vector-and-matrix-operations/page-4/
>>>
>>> Hope that helps.
>>>
>>> Cheers,
>>> Ivan
>>>
>>> On Sun, Aug 21, 2011 at 10:24 PM, Pete O'Connell
>>> <[email protected]> wrote:
>>> > Hi does anyone know if it is possible somehow to convert cornerpin
>>> values to
>>> > a 4 by 4 matrix? Seem like it would be useful for the new Gridwarp and
>>> > Splinewarp nodes.
>>> > Thanks
>>> > Pete
>>> >
>>> >
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>>
>>
>>
>> --
>> Pete
>>
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-- 
Pete
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