Alain <kua### [at] videotronca> wrote:

> It's probably that, at frame 2, you already have at least 3 objects,
> triggering the bounding for all subsequent frames.

and Christian wrote:
> It's probably not "frame 1" but "first frame rendered". How
> should povray know how many objects are in "frame 1" when it
> never processes that frame ;)

I see what both of you are suggesting--that there's nothing 'special' about
starting at frame 2 vs. frame 1, that the slowdown is based on other
circumstances. I hadn't considered that.

So I set up a weird animation test scene, to give myself a better understanding
of what's going on: 200 frames, Bounding_threshold = 2, and only 1 object in the
scene at the beginning. Then I starting adding more objects continually (simple
spheres), one after the other--but beginning those additions only at frame
100--then ran the animation from frame 1.

In this case, the slowdown only begins at frame 100 (and keeps getting slower,
far more so than the addition of a single-sphere-per-frame would indicate.) So
it really has nothing to do with starting the animation at frame 2. You're both
correct! Thanks for helping me clarify the situation.

BTW, each additional sphere added only about 900 bytes to "peak memory used", so
in my case it doesn't seem to be a memory leak--at least from the standpoint of
the "peak memory used" messages.

I decided to be thorough with my testing, so I've concocted some 'rules'
(observations) about what happens re: Bounding_Threshold (I'll call it BT below)
in v3.6.2. Some of this may be obvious to more astute POV-er's.

OBSERVATIONS:
1) If the number of objects in the scene at the *start frame of animation* (not
necessarily frame 1) is less than the BT value, nothing bad happens UNTIL you
start adding other objects. Then the renderings start slowing down at that frame
number. It doesn't matter that the TOTAL objects at that point are more OR less
than the BT value.
2) With the same set-up: If you start to *continually* add news objects at a
certain frame, one after the other, a *continual* slowdown begins at that point.
If you add only a finite number of objects at a particular frame and no more,
then a slowdown happens as well, but it's a 'finite' slowdown (for all
subsequent frames too) and doesn't get any slower.
3) Setting Subset_Start_Frame to a frame number where the scene still has less
scene objects than the BT setting, the slowdown also occurs.
4) But setting Subset_Start_Frame to a frame number *after* extra objects have
been added (as many or more total objects than the BT setting), there's NO
slowdown.

It doesn't surprise me that the intricacies of this have made the problem hard
to nail down!

Ken

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