"Bounded file" and point instancing.

[DaJuice]

Hey folks, how goes it?

Okay, I have a big field of points onto which geometry is supposed to be instanced. I wanted to try and divide the field into several smaller patches, and render with the "Bounded file" option so only the patches that are actually in view will be loaded into memory. However, it seems that when you specify a bunch of points as your .bgeo in the Bounded file option, it will still try to copy the geometry onto the bounding box that you specified at the SOP level.

Is there a work-around for this?

Thank you.

[edward]

Are you using "Bounded File (render sop bounds)" or "Bounded File (explicit bounds)" ? I'm not quite sure but I guessing that the former option will still need to cook the render sop in order to determine the actual bounds.

[DaJuice]

Hey edward,

I've tried both and it's the same thing with both of them.

[edward]

Not quite sure what the problem is then. How can you tell it's still copying at the SOP level? Perhaps a small example hip file?

[DaJuice]

Hey Edward.

I can tell because all that remains at the SOP level is a bounding box (my point patch plugged into a Bound SOP) which is what the instances get copied onto when I render. I saved out the patch itself and this is what I specify under the 'Bounded file: Geometry File' field, but the problem is that with point instancing turned on it ignores this. When you turn point instancing off again it will render the geometry just fine (provided you left some primitves in there instead of only points).

I will up an example file tomorrow if it's still necessary, but I'm thinking this would be an RFE, no?

[edward]

Oh, I see. The Point Instancing option doesn't work with anything other than Geometry As Is.

How many points have you got? I wouldn't think that would be a memory bottleneck at all. Is it just the sop network that you're trying to not cook? That could be worked around by saving out your points, and then bringing it back in using a File SOP.

[DaJuice]

Oh, I see. The Point Instancing option doesn't work with anything other than Geometry As Is.

15661[/snapback]

Yar, I figured that much.

How many points have you got? I wouldn't think that would be a memory bottleneck at all. Is it just the sop network that you're trying to not cook? That could be worked around by saving out your points, and then bringing it back in using a File SOP.

15661[/snapback]

Already done. Saved the points (400,000 total) and stripped them of all but the necessary attributes (rotation, N, pscale, instance, shop_vm_surface, shop_vm_displace, varmap). I've been experimenting with rendering this scene and how many points (stones) I can render at one time. Right now I've got it divided into 7 groups of roughly 60,000. When I try to render just one of these groups it takes my puter about an hour. If I want all 400,000 stones in one frame I would need 7 passes per frame.

There's a lot of memory overhead, which means it takes a while before mantra starts rendering the first bucket, and because of the nature of the geometry, its also pretty slow to render once it gets going. All in all it's a pretty gory situation

I've got one more idea though...

Anyways, here's an example of where I'm currently at. IIRC there were some 70k stones in this view (all points outside the camers deleted).

[edward]

Are you casting shadows? Perhaps you might be able to get away with some form of level-of-detail setting and use sprites for the far away points?

[DaJuice]

Hmm, it does render faster without shadows, and I can actually get away with not rendering shadows for many shots I think. I've also taken off the displacement shaders (yes, on the stones, and yes I'm an idiot) which sped things up. I will only need them for shots where the camera is very close to the ground where you could actually make out some detail on the little things. I played around with shading rates as well and that helped a bit too.

I like your LOD idea too, maybe I can think of something.

Thanks again.

[aracid]

hey DaJuice

have u tried turning off micro polygon rendering in ur mantra command line ?

"mantra -r"

when i was doing tests on point instancing, that setting gave me reductions in render times(especially with large objects that wre instanced), but there is a quality loss.

hopes this helps

all the best

aracid

[DaJuice]

Hi aracid,

I did try that option. I don't remember how much faster it was, but I decided not to use it because the anti-aliasing looked worse. In this case a lot of the small stones in the distance actually disappeared from the render.

Thanks though.

[edward]

LOD not with sprites but maybe cull away far away points from the instancing render entirely. For rocks which are essentially going to be a pixel big, maybe you could just render the points directly without instancing.