[Sidefx-houdini-list] uv transformation - motion blur

Larry Giunta larry at gcreativestudios.com
Thu Mar 12 15:54:53 EDT 2015

Thanks again everyone for the helpful input to point me in the right direction.

I was able to circle back today and get this working in a fairly automated way …. which I was hoping for.

Base on Emanuele's process outlined below I was able to fetch the animated "offset" channel from the uv texture SOP into CHOPs.
…. and then drop on a slope chop to calculate acceleration/speed.

I then followed that up with math and limit chops to clamp/normalize the value to an appropriate level for velocity.
Export that back to a point SOP to add velocity( in the proper direction) and I can now render with motion blur based on the motion of the sliding ( stopping/starting) UVs.

Thanks again. I'll need to store this away for future use.


On Mar 11, 2015, at 3:04 PM, Emanuele Paris <claude.akabane at gmail.com> wrote:

> Couldn't you also just try and use the offset speed to compute v? I'd imagine the sliding has animation right? So it can start and stop. Well, you can compute the difference in offset between 2 frames, normalize and multiply arbitrarily for the amount of moblur desired? Of course using "v" means you have to te the geometry to use geometry velocity for motion blur
> E
>> On 11 Mar 2015, at 18:28, Larry Giunta <larry at gcreativestudios.com> wrote:
>> Hello all, 
>> I wonder if I'm overlooking a straight forward way to render a sliding texture with motion blur?
>> I'm working on a shot for a spot where the paper/tape of an adding machine needs to flow out quickly …. but in stops and starts.
>> I could use a creeping surface so I can compute velocity…. 
>> But sliding the UVs feels a lot lighter and quicker to work with.
>> Just not exactly sure how to convert that motion into some velocity value that mantra will recognize.
>> I've addressed this issue in the past ( in a crunch ) just by blurring the texture horizontally.
>> But the required stops and start in the paper flow here make that a bit more cumbersome to deal with.
>> Anyway …… thanks as always for any thoughts.
>> Larry
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