Thank you very much, Ivan.
yours works as expected. Now I have to find out where my mistake is.
THANKS,
Vincent
2016-10-28 19:06 GMT+02:00 Ivan Busquets <ivanbusqu...@gmail.com>:
> Hey,
>
> I don't have much time to recompile C44Matrix these days, but as Vincent
> points out, the source is available, so if anyone wants to compile it and
> contribute it back, I would be grateful for it :)
>
> This is how I would do depth-to-position using C44Matrix (copy-pasted
> nodes below)
>
>
>
>
>
> Step by step, this would be:
> 1 - get your pixel X,Y coordinates
> 2 - go from pixel coords to NDC (using a C44 Matrix for this, but you
> could easily just normalize to a -1 to 1 range)
> 3 - project that vector outwards (using the inverse of a projection matrix)
> 4 - scale that vector so the Z component is equal to your depth
> 5 - add any camera transforms (translations, rotations...)
>
>
> Hope that helps!
>
>
> set cut_paste_input [stack 0]
> version 9.0 v8
> Dot {
> inputs 0
> name Dot3
> label cam
> selected true
> xpos -618
> ypos 2313
> }
> set N108b1a10 [stack 0]
> Dot {
> name Dot9
> selected true
> xpos -618
> ypos 2414
> }
> set Nf803fb0 [stack 0]
> Dot {
> name Dot8
> selected true
> xpos -618
> ypos 2586
> }
> push $Nf803fb0
> push $N108b1a10
> push $cut_paste_input
> Dot {
> name Dot4
> label "input with depth"
> selected true
> xpos -751
> ypos 2137
> }
> Expression {
> expr0 x
> expr1 y
> expr2 1
> expr3 1
> name Expression4
> label "r = x\ng = y\nb = 1\na = 1"
> selected true
> xpos -785
> ypos 2194
> }
> C44Matrix {
> inputs 2
> matrixFrom "from camera input"
> matrixType format
> invert true
> name C44Matrix_v01_3
> label "matrix type: format\ninvert = true"
> selected true
> xpos -785
> ypos 2297
> }
> C44Matrix {
> inputs 2
> matrixFrom "from camera input"
> matrixType projection
> invert true
> name C44Matrix_v01_4
> label "matrix type: projection\ninvert = true"
> selected true
> xpos -785
> ypos 2398
> }
> Expression {
> expr0 "(r * -depth.Z) / b"
> expr1 "(g * -depth.Z) / b"
> expr2 -depth.Z
> expr3 1
> name Expression5
> label "r = (r * -depth.Z) / b\ng = (g * -depth.Z) / b\nb = -depth.Z\na = 1"
> selected true
> xpos -785
> ypos 2472
> }
> C44Matrix {
> inputs 2
> matrixFrom "from camera input"
> name C44Matrix_v01_5
> label "matrix type: transform"
> selected true
> xpos -785
> ypos 2576
> }
> Dot {
> name Dot7
> selected true
> xpos -751
> ypos 2673
> }
>
> On Fri, Oct 28, 2016 at 8:25 AM, Vincent Langer <m...@vincentlanger.com>
> wrote:
>
>> the source code is on nukepedia as well.
>> cheers,
>> Vincent
>>
>> 2016-10-28 17:14 GMT+02:00 Erwan Leroy <er...@erwanleroy.com>:
>>
>>> Ah, got to get my hands on that c44matrix so that I can see the result.
>>> Is Ivan still in the mailing list? Any chance to compile a new one? Or
>>> is the source code somewhere?
>>> It's an interesting challenge.
>>>
>>>
>>> On Friday, October 28, 2016, Vincent Langer <m...@vincentlanger.com>
>>> wrote:
>>>
>>>> Hi Erwan,
>>>>
>>>> ah I did not know about cx and cy - good to know- BUT the whole thing
>>>> is for a deep tool and cx and cy do not work in deep expressions. this also
>>>> answers the question I am why not using the DepthToPosition node.
>>>>
>>>> focal length and aperature size is considered by the c44Matrix node in
>>>> projection mode.
>>>>
>>>> cheers,
>>>> Vincent
>>>>
>>>> 2016-10-28 12:33 GMT+02:00 Erwan Leroy <er...@erwanleroy.com>:
>>>>
>>>>> Hi
>>>>> Maybe you are doing it for the challenge, but is there a reason why
>>>>> you would not use the DepthToPosition node built into Nuke? I seems to do
>>>>> exactly what you are trying to do (I get a very small error which I
>>>>> believe
>>>>> is due to rounding).
>>>>> For the fun of it I looked into your expressions, but couldn't go all
>>>>> the way through because there is no current build for the C44Matrix for
>>>>> Nuke 9 on windows.
>>>>> I have 2 things that I believe might be affecting your result (but I
>>>>> can't verify):
>>>>>
>>>>> - I don't see you consider the focal length anywhere? That would have
>>>>> a big impact.
>>>>>
>>>>> - Now this might not apply for every renderer, and Nuke's built in
>>>>> node ignores that point as well: In your first expression, you generate a
>>>>> "default" position point cloud, with X and Y as planar coordinated, while
>>>>> possibly using a "curved" Z_Depth for you Z input. In real world (and Vray
>>>>> for exemple) the distance a of a card right in front of a camera would not
>>>>> have a single value, as the distance on the sides of the frame would be
>>>>> greater than right in front of the camera.
>>>>> See attached pictures that illustrate this point.
>>>>>
>>>>> (Also, for that first expression, why not using cx and cy instead of
>>>>> that complex expression)
>>>>>
>>>>>
>>>>> Cheers
>>>>>
>>>>> *Erwan* LEROY
>>>>> www.erwanleroy.com
>>>>>
>>>>> On Fri, Oct 28, 2016 at 4:04 PM, Vincent Langer <
>>>>> m...@vincentlanger.com> wrote:
>>>>>
>>>>>> Hi there,
>>>>>>
>>>>>> I am trying to get the math right calculating the worldpositions from
>>>>>> z information + camera matrices.
>>>>>>
>>>>>> my result is close to the rendered position pass - but does not line
>>>>>> up perfect.
>>>>>>
>>>>>> Maybe one of the brains out there can tell me what I am missing/doing
>>>>>> wrong
>>>>>>
>>>>>> This is just a proof of concept for the right math and I use the
>>>>>> C44Matrix node from Ivan Busquets.
>>>>>>
>>>>>> cheers,
>>>>>> Vincent
>>>>>>
>>>>>> --
>>>>>> Vincent Langer
>>>>>> Uhlandstr. 29
>>>>>> 71634 Ludwigsburg
>>>>>> +49 176 965 177 61
>>>>>> www.vincentlanger.com
>>>>>>
>>>>>> _______________________________________________
>>>>>> Nuke-python mailing list
>>>>>> Nuke-python@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/
>>>>>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-python
>>>>>>
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Nuke-python mailing list
>>>>> Nuke-python@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/
>>>>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-python
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Vincent Langer
>>>> Uhlandstr. 29
>>>> 71634 Ludwigsburg
>>>> +49 176 965 177 61
>>>> www.vincentlanger.com
>>>>
>>>
>>>
>>> --
>>> *Erwan* LEROY
>>> www.erwanleroy.com
>>>
>>>
>>> _______________________________________________
>>> Nuke-python mailing list
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>>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-python
>>>
>>>
>>
>>
>> --
>> Vincent Langer
>> Uhlandstr. 29
>> 71634 Ludwigsburg
>> +49 176 965 177 61
>> www.vincentlanger.com
>>
>> _______________________________________________
>> Nuke-python mailing list
>> Nuke-python@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/
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>>
>
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>
--
Vincent Langer
Uhlandstr. 29
71634 Ludwigsburg
+49 176 965 177 61
www.vincentlanger.com
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