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matching maxwell cam to use with cinema object channels

Posted: Wed Apr 22, 2009 8:03 am
by deadalvs
hi ..

for some post-work, is it possible to match the m~w cam to the cinema cam to render perfect object channels. no DOF needed or absolute minimal.

i tried some high f-stops, but there were still some edge pixels a little off.

how can i get closer to the real deal ?
what camera values should i use ? (will it ever match within less than a quarter pixel ?)

i'm using render tags for about 20 channels.

* * *

:roll:

Posted: Wed Apr 22, 2009 1:31 pm
by mashium123
Sorry for the question, I'm sure it's just me, but I don't really get the setup.

Are you trying to immitate a cam that you previously defined in studio within cinema4d?

I would have thought, an easier way would be to set the scene up in c4d first.

And then - after having defined pov and such - exort/render the whole thing straight out of c4d. Eventually "postwork" in Studio...

But probably I'm misunderstanding the task.

Posted: Wed Apr 22, 2009 2:07 pm
by deadalvs
yes, a little misunderstanding.

i got the scene in cinema and render the mx cam from there. but i'd like to render the same cam in cinema for all the object channels (glass, walls, floor, ... ) for maxwell-postwork.


:)

Posted: Wed Apr 22, 2009 2:08 pm
by deadalvs
actually the problem's like setting the maxwell cam to infinite focus like cinema's cam renders. that's mathematically impossible since maxwell always renders DOF, but that's why i wanna minimize the effect.

Posted: Wed Apr 22, 2009 2:17 pm
by mashium123
ah.. ok.. then it's about loosing the softening edges, created by too realistic maxwellian dof... hmm...

to minimize the mr dof wiith the help of c4d, I'd suggest the trick put your complete setup (together with the cam) in one group, and scale that group by an amount that is big enough to get close-to-rid of the dof.

I guess, when you shoot a screw for example, the render would show a lot less dof effect, if that screw would be 500m wide instead of 5cm... together with the adequate f-stop...

Posted: Wed Apr 22, 2009 2:31 pm
by deadalvs
could that be done simply by the scene multiplier ?

Posted: Wed Apr 22, 2009 2:46 pm
by mashium123
deadalvs wrote:could that be done simply by the scene multiplier ?
never tried it that way, but worth a try.

Posted: Wed Apr 22, 2009 2:55 pm
by JDHill
Yes, the easiest way would probably be to set Scene object > Cinema > Export Units to meters. You can also make sure your camera has Lock exposure to EV on, then crank the fStop up to 30 or more; that should get things rendering sharp.

Posted: Wed Apr 22, 2009 3:32 pm
by deadalvs
hmm .. tried this ..

with some 100cm spheres, set to export as kilometers (!) and fstop 50 most edges are still off by a pixel, leaving color corrections with an ugly border.

could there be an issue with premultiplication that cinema (or maxwell) calculates wrong ?

Posted: Wed Apr 22, 2009 3:55 pm
by JDHill
I guess that would be difficult to say. I don't know that what you're referring to would be considered 'wrong' on the part of either, depending on whether or not the deviation has to do with the numerical precision involved in figuring/transferring camera location, direction, fov, etc. - as well as whatever goes on inside the two engines regarding aa and such. So this also really depends on what a pixel means - are you rendering 50x50 or 5000x5000?

Posted: Wed Apr 22, 2009 4:04 pm
by deadalvs
that's an important point .. that's why i've rendered @ 1600x1200.

but this may still be not enough .. i shall try 3K or 4K.



:P