> In the radiosity section, do you change error_bound? To what extent? When you
> push it down, the rendering time increase. It also requires a higher count to
> prevent splotshiness, resulting in still longer renders. One of the main reason
> to use small error_bound is to produce sharper and deeper shadows.
> You can try lowering pretrace_end. At the cost of more pretrace time, it may
> allows you to use more relaxed settings elsewhere, resulting in globaly faster
> renders.
> Do you have "normals on" in the radiosity block? Normal computation in radiosity
> is very computationaly heavy. If you can do without, remove normals on.

/> My radiosity settings are pretty default, the count is set to 35, the
error_bound is 0.2.  I do use media on, but I don't think I have normals
on.

> Do you have large difference/intersection where you remove 100's small pieces
> from a large base object? You may try diferencing a blob instead of many spheres
> and cylinders. You may also try using merge to combine all the pieces that you
> remove. That way, you only test 2 bounding box instead of one for each components.

/> I do use a macro that creates my circular brick walls, I tried several
methods for creating rounded brick walls, and finally came up with an
isosurface that could do it from the outside, but I needed texture on the
inside, so i was forced to use CSG.
I used merge wherever possible, and tried bounding the wall manually, but
there was no significant speed increase.

> If you have an isosurface with some very large max_gradient, Using the log,
> square root or cube root of the function may allows you to reduce max_gradient
> to a more reasonable range, speeding up it's rendering.

/> My heaviest isosurfaces are the ones I used to carve runes into the
floor, they typically have a ridiculous max_gradient, and I'm looking for a
suitable runic font to replace them with.

> Many reflection or refractions? Lots of total internal reflections? Try
> increasing adc_bailout. In some cases, the visual impact is negligeale, but the
> resulting speed up very interesting. The default is 1/256, depending on the
> scane, you may get by with as much as 1/100 or even 1/64 without to much
> negative impact!

/> I have considered trying that.

> Any glossy object? phong and specular don't work with radiosity. You can get a
> similar effect using a small amount of blured reflection, but it will increase
> the rendering time.

/> This is the real killer, besides the light sources, or perhaps because of
them.  I have many glossy and reflective surfaces, the floor is highly
polished, as are the columns, and there are silver accents and features
throughout the scene.

> Filtering and scattering media never react to radiosity, they need actual
> lights. Emissive media can illuminate radiosity if you use "media on" in the
> radiosity block.

/> I use massive amounts of emitting media in the scene for flame effects,
and it does render rather slowly, but I've learned to live with it,
considering the effects.

> Simple textures can't be optimised, they are as simple as can be. Layered ones
> can be worked upon. You need some test scene with some simple objects to receive
> your test textures. Start with your layered texture on one object. Now, on
> another object in the same scene, try to emulate the complex texture with a
> simpler one. Once you find a suitable, simpler texture, copy it to your real scene.

/> I am currently pulling almost all of my textures straight from the
standard texture library, specifically stones.inc (The textures there are
much better than most of my attempts.)

> In some cases, using light_group can significatively improve your rendering time.

/> I did introduce a light group, to limit the effect of the light_sources
to the candles only, the speed increase that resulted was nothing short of
incredible (Well in excess of 500%.  In twelve hours, it had rendered
almost half of the scene, when previously, it had taken several days to
render less than a quarter.)

Thanks for the input.

ADB

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