Optimizing Meshes for Quick Renders

Folks, I’ve been digging around for answers to this problem, but I’m not having much luck.

I’ve dusted off an old ship model I built three years ago in Blender to see how well it would render in the current release – you know, throw raytracing, ambient occlusion, area lights, etc. at it just to see how much better it would look. Naturally, I expected this to take longer, but I was kind of surprised to see my brand new computer, using the latest version of Blender grind nearly to a halt. Hours would pass before more than a few horizontal lines were rendered! Now if I turned off ray-tracing, things picked up nicely, giving me my renders in just a few seconds, but I want raytracing for the superior shadows it yields.

After a little experimentation, I learned the problem was the plane I used to represent the ocean surface. Without it, the model rendered extremely quickly. When I put an ocean plane in that was a little bigger than the ship, the whole thing rendered in just over eight minutes. When I doubled the size of this plane (and made no other changes at all) the rendering time shot up to over twenty minutes. To realistically model the ocean, this plane needs to be twenty or thirty times larger, but then we’re back to really long render times again.

So finally, we get to my question: Are there any other settings for World Size, Cameras, Lights, whatever, that might help me around this problem? Is there a parameter that tells Blender’s renderer to cope with large objects better? I need a big ocean, tiny details on the ship (fire extinguishers can be seen if you’re close enough), and ray tracing for great lighting and shadows.

This is a render done in 2001 so you have an idea what I’m trying to do:


Try increasing the Octree size. This function is explained there: http://www.blender3d.org/cms/Render_engine_features.215.0.html


If you are using wave effects, lower the number of verts as the water keeps getting farther away. For example:

CameraHighres Water----boatMediumres Water-----*Lowres Water

Also, for purposes of renders, create a copy of all the models, and delete all unimportant verts (I.E. all which won’t be seen/shadowed/reflectioned).

That’s all I can think of right now.

Martin! Thank you! As soon as I read your post, I knew that was exactly what I was looking for. I managed to render the following variation of the model (based on the above and made shortly after) in six minutes, fifteen seconds.

Now, I’ll just have to find time to go back and update both models with newer techniques. And do something about that water.

Thanks again!

Smoky Joe, nope, no wave effects at all yet. This model wasn’t built for more than a fly-by animation, and the water wasn’t going to be visible long enough to get much out of animating it. As a result, it was just a simple plane stretched out beyond the mist. Now, however, I’m starting to think about how much fun it would be to do more with it. When I do, I’ll be sure to keep your suggestion in mind.