I thought hair jitter was addressed a while ago......

It seems it is has returned.

Is there a way to mitigate it?
We used to go into groom mode and groom the hair at the begining of the frames and again at the end.
This seemed to give the hair "something to do" instead of twitching.

EDIT: we are using tree images as hair with V13.0 with Net Render.

Any help is appreciated!!

David

Sounds like NetRender is the culprit...try a short test just renderring on 1 local processor... ?

Matt,
I hope that is not the case cause I REALLY need to render this project on the farm.

To render a single view on one machine will take days...........

David

Did you ever get to render with these models in version 12 or can you go back and render in v12 to see if the hair renders correctly?
Our models with hair are rendering out fine in v12. As a side note we do not have collision detect on.

Jack,
We converted the projects to V13, so rendering in V12 isn't likely.

There is no collision detection as they are just trees.

The only thing I can think of is there were errors on some of the slaves and they had to be restarted.

I will rerun the render to see if it occurs again, and will post the results.

David

I have seen a lot of this. And there as been much discussion on this. I've gotten hair jumps in both v11/12 NetRender and in v12 AM (just rendering on one pc with AM). Note that the hair has to be quickly moving about for this to show in AM. I have reported this and in fact just received an email to send in an example project. The NetRender problem has been around for a while == I'm pretty sure I reported this some time ago but I'll have to check.

There was supposed to be a workaround for the Netrender hair jump -- as I recall you have to create separate ques (as many as needed) and only put one slave on each. Each que does a consecutive group of frames AND each must render out frame zero before it starts its group of frames (to sync them I guess). I have not tried this.

I'd bet the bank that V13 has both the AM and Netrender flavor of hair jump but, sadly, I've been forced to back down from 13 because of issues with porting my models to 13.

Cheers,
Rusty

David,
I hope your re render works out. Just the words re render makes my hair stand on end. I am very interested to hear of the results.

This time it rendered without jitter.
Things noticed:
While rendering the project, 3 of my slaves became hung up on the frames they were doing, meaning they were sitting on the frame at different percentages. They did not all become hung up at the same time.

When I had rendered this same project ealier, the slaves (not the same ones as hung up the most recent render) had become hung up and I killed the render on them, re-booted the machines, re-started NR.

This last render, I just took those offending slaves off without re-starting them.
I typically like more data before I develope an opinion, but it seems there is a relationship between restarting a slave and jitter.

The only other thing that was different is I did not use a really slow slave machine in the render.
While the slaves were "hung-up" the render dialog box on each machine said they were rendering patches.
If anyone can comment on this issue I would appreciate it very much.


Thanks,
David

That is great news once again about v13. Hair is rendering like it does in v12. Outstanding.
With your hang problem All i do know is that in v11 I was having them all the time do to specular hits on certain frames being to hot. In v12 that has been eliminated completely. I did get some hanging once with a project in v12 and what it turned out to be is that the project was just to large and was maxing the virtual ram. So I down sized the project into the ram range of the nodes and i do not get frame hangs any more thank god.

ARe your nodes needing to use virtual ram to render the project?

Jack all I can say is the render completed without hair jitter.

How would one know if the slaves were "needing to use virtual RAM to render the project"?
I guess I thought they all did.
How does one "size" a project? Remove objects?

Thanks for the info!

David

open up a project in AM.
bring up task manager and look at performance this will tell you how much ram is being used to have the project open.
If you have a gig of ram and you see it showing more than a gig than your using virtual memory off of your hard drive.
To down size a project you will need to think how you will composite the shot in another program as in layers. I use after effects. Am does come with the composite ability by adding layers if you do not wish to use After Effects.
Why I use After Effects over the AM composite layer is that After Effects gives a lot of power in the area of adjusting layers or adding effects to layers.
Once you start to composite you will never go back it just give you so much control and creative adjustability in so many ways.

Jack,
I have AE and have used it for compositing smoke and logo overlays but that is about it.
More than likely I don't understand the power of compositing, if I had a better handle on it I could apply it better.

I really don't like to composite the smoke in later, there is always something about the frames when you import them in AE where the timebase is not the same as the original frames. In some places the smoke is to early and there is a visible gap between the smoke and the object smoking, next there is an overlap.

I do like the the ability to adjust the opacity to get the right look.

David