Windows, sunlight, and different render types

[JRoth]

OK, I'm being completely flummoxed by lighting and windows in various rendering modes. I'm rendering the interior of a church, so the lighting from/through/of the stained glass is critical.

The glazing in my stained glass is By Class, using a texture ("Stained Glass 1") that is set to be Transparent by Color Filter (using a light buff). The sun object is shining directly through the windows. As a control, I've switched one window to being Clear Glass, per the Window Settings dialogue.

In OpenGL with shadows turned on, the whole interior is dimly but uniformly lit, with light on the floor through the Clear Glass window. The stained glass texture in the other windows appears opaque - it is no brighter than the adjacent walls.

In Fast Renderworks with Shadows, I get light on the floor from all of the windows except the Clear Glass one, although the Clear Glass window at least appears bright and I can see through it. The room as a whole is quite dark; I need to turn on Layer Ambient to be able to see anything but the sunlight on the floor.

In Final Renderworks, everything is completely black.

Fast Radiosity looks awful (weird splotches of highlight and lowlight), and has no sunlight on the floor.

Final Radiosity completely bogs down my machine (incidentally, just last night it rendered a simpler interior with artificial light at a decent speed).

What on earth is going on, and how do I fix it? Would having a Renderworks HDMI background help? I haven't had a lot of success with those, either.

As far as what my client is looking for, the bare minimum is what I'm getting with Fast RW + Shadows, but I've told him I can do better than that.

[Horst M.]

Hallo JRoth,

It's hard to say, what exactly causes the Final Quality Render to be black, without seeing your Setup.

I suggest, that you play a bit the settings in Custom Renderworks or Custom Radiosity.

In both Cases you should set the Number of refractions in the Render Section of the Setup for "Custom Renderworks Options" or "Custom Radiosity Options" to a low value, like 4 or 8

This effects the rendertime extremely.

I find it also usefull to klick on Auto Exposure.

Horst M.

[billtheia]

No idea why the FQRW render is all black. Take a closer look at your glass textures.

Because you're using an exterior light source to light the interior of a space, you'll need to turn on final gather in Custom Renderworks or use Radiosity. You need to get the light to bounce around to light the interior. Renderworks (without final gather) only gives you a "single bounce." Radiosity bounces the light around - it attempts to simulate real-world lighting. Custom Renderworks with final gather uses "trickery" to give similar results in less time.

Keep in mind that Renderworks will make use of multiple processor cores. Radiosity does not. In some cases, Custom Renderworks will render faster than Radiosity while giving similar results. EIther way, your renders aren't going to be fast.

If you can upload a sample file, we might be better able to help.

[islandmon]

To save time & frustration testing the various settings...

try running your rendering tests using a Sheet with a low dpi ...

and crop the View Port to only display a representative 'slice' of the final image .

[JRoth]

Thanks for the tips, everybody.

Feel free to keep more coming - this is a big space, so it's hard to light with individual lights unless I get some bouncing (and some smart rendering choices)

Edited February 12, 2010 by JRoth