Can't get mantra to render a scene

[magneto]

I have a scene with 100k points nurbs but when I render, it took the mplay window to just show up and wait there in its initial small size, not the one that scales itself to your output res, but after 30 mins, still the same. I restarted Houdini and when I click Render, it shows the same dialog but now it says:

Mantra

no image

Any ideas on how to fix this?

[gaurav]

I have a scene with 100k points nurbs but when I render, it took the mplay window to just show up and wait there in its initial small size, not the one that scales itself to your output res, but after 30 mins, still the same. I restarted Houdini and when I click Render, it shows the same dialog but now it says:

Mantra

no image

Any ideas on how to fix this?

You may try :

If it is mantra problem where is render is taking too long which you can check at two places.

1. Render>Scheduler.

or

2.Change verbose level to 1 found at mantra rop >properties>stats>

Check shell for Render Time and Memory taken where :u will be cpu time and :s is the system time.

With mplay things are little differnt as it involves a lock file and i dont fully understand how things are working under the hood.

It was little messy with my previous installation and gave me two mplay windows when launched.

Try disconnecting mplay. Render > disconnect, and choose listen for renders

again and render.

I am not too sure if that would solve it.

Cheers,

[symek]

Something broken, post simple example.

[magneto]

Thanks guys, I made a simple example that has the same problem

render shape.hipnc

[gaurav]

Hey

Whats up with 10k division on simple nurbs circle , Do you really need that. ?

Reduce it to 10 and see surface is still the same and it will render fast.

Afaik mantra does not know how to render nurbs directly hence refines it in micro polygons.

And that takes kills your memory, so reduce the geomerty which requires refinement like nurbs.

At lease thats the case with both micropoly + raytracing engines when it comes to nurbs surfaces. If i am not wrong

Master SYmek could shine some light on it and explain it in detail.

Cheers,

[symek]

That's the funniest example of how to put renderer onto its knees I've seen. You're my hero .

You've created 10000-points single nurbs curve (closed) and ask Mantra to render it. Well, generally renderers prefer polygons, but funny thing is, that even converting it into polygon (10000-gon!) won't work. Mantra freezes somewhere below 5000-gon). Apparently you've found its limits .

I also see there width attribute, which does work for open curves, so did you want to render a curve or a surface? Because a curve renders fine with this amount of vertices...

If you were about to render surface, here are my suggestions:

1) generally avoid rendering NURBS. Polygons almost always render faster and less error-prone these days (though less accurate obviously).

2) avoid > 5000-gons . If your circle has to have 10.000 vertices, add DivideSOP to split it after into smaller ngons (use parms: "Bricker Polygon" or "Maximum Number of Edges").

3) Do you really need these 10000 divisions? I mean your scene renders exactly the same with 10 or 10.000 edges... as I understand this is only example, right?

EDIT:

1) ups, vectorblur bit me,

2) H12 doesn't do any better with gazillion edges.

Edited February 6, 2012 by SYmek

[magneto]

Thanks guys, yeah this was just a simple example not the real curve I was trying to render

In my original case the shape is much more complex and is quite long which I modify using VEX.

@Symek, I didn't know the width only worked on open curves but yeah in my original curve, it's open and that's how I was using it.

In this circle it renders, but in my case of 50k points, it didn't. I actually used a Resample SOP to evenly divide the curve. Now I increased the length to reduce to points down to 20k, and it renders fine.

So I understand it doesn't like 5000-gons which I don't have it in my real example, but would having 50k+ points also cause render problems even if the curve is open and rendered using width?

Thanks guys