Hi, I'm getting that thing where mantra quits the render halfway through when rendering as subdivision surfaces. Turning on verbose output mentions this:

mantra: Mantra caught signal 11

From what I gather this can happen when you copy VOP networks from one file to another (or from one version of Houdini to another?). The problem is confined to displacement shaders that use textures (Texture VOP, Color Map, Bump Map VOP). When I set the displacement height to 0 it renders fine. When I replace textures with procedural maps it renders fine. When I delete the uv attributes on my model it renders fine.
Any ideas?

Hi DaJuice,

It sounds like Mantra is crashing because of subd's. To rule that theory out, try leaving everything as you would like it to render, but instead of rendering the geometry as subd's, do the subdivide at the SOP level and not in the render. If that works, then my guess is that, for your particular case, Mantra is crashing with subd's.

Hope that helps,
George.

Yes, sorry, I know that this only happens when using subdivision surface rendering. I was rather wondering why it was doing it and if anything could be done about it. I know others have experienced this as well, it's just the causes have been hard to pin down I think.

You could try a CleanSOP - try to make sure there are no zero-area polys and such. What version are you using?

I have to say I get loads of mantra caught signal 11's and it's nothing to do with any of the above IMHO.
I only get them on very large print res renders, 7k size, with stacks of geometry on. With no subd's being used and no VOP copying going on, these renders come straight from ifds.
Unfortunately mantra caught signal 11 is a very generic error message and doesn't really help pin down the problem. I also get mantra terminated with an unspecified runtime error, again not very helpful.

A couple of years ago we had these all the time, again with loads of geometry in the scene but much lower res. We were losing about 5-10% of large renders. Turned out mantra had a bug in it where quads weren't getting correctly converted to triangles in the renderer.

Fortunately we now only get this in the cases mentioned above and I haven't had time yet to pin down anything specific that causes it.

The only other thing I can say is often when we get frames that don't render we just render them straight to an mplay window and that fixes the problem.

Hi Jason, I'm using 7.0.192. I tried the Clean SOP, and although it got rid of a few primitives somewhere it did not fix the problem. Thanks though.
And thanks for all the info Simon. Actually I don't think the problem has to do with copying VOP nets across Houdini sessions. The problem, in this situation at least, lies somewhere between H6 and H7. The original model was finished in 6.1 and that file renders just fine. Opening that same file in Houdini 7 (no warning or error messages given) and hitting render is where the problem starts.

Again, if I take off the displacement shaders, and render just the surface shaders it works fine. And if I delete any UVs used by displacement SHOPs it works fine also (of course the image looks jacked up for lack of UVs). I tried recreating the displacement shaders from scratch for the Houdini 7 file, thinking that maybe something carried over from the H6 shaders was screwing me up, but even the simplest of displacement VOP nets doesnt work. The weird thing is that the standard VEX displacements, like v_choppywater, work fine. :?

DaJuice, you might want to try using Houdini 6.1 to generate an IFD file. Then try rendering using Houdini 7's mantra. That would rule out the problem with cooking your SOPs differently.