In broad terms, moving reflective surfaces and motion blur generally aren’t a
problem for raytracing renderers, because there aren’t relying on tricks or
workarounds.
-Nathan
From: Elias Ericsson Rydberg
Sent: Saturday, September 28, 2013 1:36 PM
To: Nuke user discussion
Subject: Re: [Nuke-users] motion blur in reflections
I'll second Nathan.
Doing motion blur in 3D seems like your best bet. I know that motion blur in
reflections in some renders can be tricky. A great example is a spinning chrome
sphere, which shouldn't make the reflections become blurry. Sure the surface
being shaded is moving but should not affect the reflections in any way.
Possibly it was 3delight where you had to be cautious about this, however,
doing it in 3D will save you a very intricate comp. Specially if there's a lot
of different moving parts that are reflector. Eg. the internal gears of a watch.
/Elias
28 sep 2013 kl. 21:39 skrev "Nathan Rusch" <[email protected]>:
I would say definitely just render your 3D with motion blur. Given the nature
of your scene, the time it will take you to get a comp solution working that’s
even close to “good enough” will more than cancel out the time you could save
by avoiding it in 3D, and doing it right will always look better.
-Nathan
From: Ryan O'Phelan
Sent: Saturday, September 28, 2013 7:55 AM
To: Nuke user discussion
Subject: Re: [Nuke-users] motion blur in reflections
The mirrored camera is the best choice because you can maintain a true pass
system in the reflection(you will have diffuse, gi, etc.) , which you can't
do otherwise.
If you are feeling adventurous, you could try projecting a velocity pass on
your geo, from a previous render, and then rendering the reflection. Your
vertical vector will be inverted, but that's easy to fix in comp.
Personally, I would stick to motion blur in camera. Lazy, I know.
Ryan
On Sep 28, 2013 2:50 AM, "matt estela" <[email protected]> wrote:
I'm no v-ray expert either, but knowing that vray can be treated as a pure
path-tracer like arnold, and getting motion blurred reflections from a
pathtracer is down to spreading your reflection samples over time, I'm sure
v-ray could do this happily, albeit slowly. Did a quick google, found some
images that imply it can do it fine:
http://www.cg-blog.com/index.php/2013/04/11/vray-motion-blur.htm
(the first overly-streaky motion blurred image, you can see matching
streaked reflections on the floor).
You might have misremembered in terms of exporting motion vectors and
applying blur in comp, in which case yes, there's no easy way to capture that
in the render, and you'd need to do the cheats you've described.
Another way would be to take your render camera, duplicate it, mirror it on
the ground axis, render your reflections through that second 'reflection'
camera. That way you could still export motion vectors, and keep it all in
comp. Depends how clever you wanna be, vs just brute force render your way
though it, which is becoming the norm these days.
On 28 September 2013 16:18, adam jones <[email protected]> wrote:
Hey hey
I ask this question with the feeling I might have over looked some thing.
I know this is not a vRay forum but I just want to give you the complete
story
Ok am about to commence comp work on a TVC I have a mechanical object
moving across a mirror like ground surface, this object will have various types
/ directions of MB going on some from its direction of movement but also
spinning wheels and cog with MB.
Now from what I remember (might be different in newer version of the vRay
render) the MB is a vary post task being that it will not be shown in the
reflections on the ground.
I have a couple of ideas of how to get this MB into the ground
reflections but they don't feel to elegant.
one thought I had was….
there use to be a gizmo floating around that you could cast ground
shadows with a projection camera, I just can't remember if it required I piece
of geo or and alpha to do it, does an you remember this gizmo.
also if any one has some ideas and or pointer that would be cool.
keeping in mind that the ground surface will need to produce some what of
a clean reflection.
thank you all
-adam_______________________________________________
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