Cached cloner disappears on single frame

#1

I’ve had this weird bug turn up before and never got to the bottom of it.

I have a cloner composed of several dynamic objects moving down a spline.
The cloner has been cached with the mograph cache tag.
If I play the animation the viewport, everything looks fine.

When I render the sequence, the clones completely disappear from the scene on one particular frame.The rest of the sequence renders correctly.

i thought maybe it was just a renderfarm glitch so I tried rendering just the one single frame locally, but that frame renders without the cloners as well (even though they are there in the viewport.

I dont want to have to re-cache the scene for fear of it solving slightly differently, which means I’ll hae to re render the entire scene again. There are also many cached dynamic clones in the shot so they will all have to be re cached as well.

As I mentioned–this has happenned to me before and I dont believe I ever figure out why it happens. I usually find a workaround but thought I’d see if anyone else has had this happen or knows what causes it.

Thanks.

#2

Turning off render instances in the cloner fixed the issue. The clones render.

Anyone know why this may be? I believe this was the solution the last time I had this issue as well.

#3

Are you rendering with motion blur? I get issues where an object will disappear in an epic blur of random un-keyframed motion (regardless of render engine), which I try to fix by increasing moblur substeps or (inevitably) re-rendering out the sequence without blur and trying to add it in post.

#4

Hey Luke–thanks

No moblur. Physical render with mo vector pass however (though that shouldnt affect the beauty pass)

#5

Are you using an external cache with R18, or an internal cache?

Yesterday morning I submitted several issues to Maxon regarding the external cache, but haven’t heard back yet.

#6

In this case --internal

#7

Hmm. My thought was that if it was external you could examine the .mog file for that particular frame to see if there was an issue but that’s not an option.

Internal caches definitely appear to be more reliable, but - as in this case - its difficult to diagnose the issue.

#8

Thanks for the feedback Luke–I do appreciate it. As I mentioned–this has happenned before, to me and to people I’ve worked with. Looking back through my old notes–it seemed to have something to do with render instances versus straight clones each time. In worse case scenarios–I can bake out the clones to keyframes too. Havent tried the external cache option yet with mograph but have been meaning to.

#9

I had some wonkiness a few weeks back with caching dynamics, which I don’t ever think I’ve ever seen pre-R18.

I don’t recall the details, just that it wasn’t performing as expected.

#10

Excellent tip. Saved my bacon, many thanks.

#11

Same trouble, since a few days, I bake them, without uncheck render instances :frowning: I tried external cache too … So now I know what is buggy ! Thks

#12

Render instances seem to have a lot of problems, I always turn them off, unfortunately. Would be great if it was a stable feature.