Lighting a room with environment texture + sun lamp [and a volume question]

Support Lighting and Rendering
1

Hey,
I have recently started with blender and watched some tutorials and stuff already. Currently I am running Blender version 2.78c and using cycles renderer.
Now I was starting my first attempt at architectural modelling and ran into a problem I can not solve.

I built a room with a table in it, some glass textured windows and an environment hdr texture to light the scene. You can check the scene in the attachments.

The problem now is, that the room is very dark as it is lit by the environment texture only. Putting a sun lamp outside and having it shine into the window does exactly nothing.

Is this normal behaviour? And if so, what aspect of the video tutorials I have watched did I missed?

Also there is a second thing I do not get. When I turn on volumetric lighting and set it to volume scatter, the whole scene becomes black. Only setting the density to 0.0 prevents the result from being black, but then there is no volumetric lighting active.
What am I doing wrong here?

Thanks in advance and sorry for the mediocre English skill.

Attachments

Orange.blend (674 KB)

2

Try adding a transparent shader and a mix shader to your glass with the factor being shadow ray (from light paths).

You also want to put a light portal (https://www.blenderguru.com/tutorials/using-portals-accelerate-render-times/) at the windows to direct the light.

3

Your use of a glass shader for the windows is not advisable for two reasons:

a)
Using refraction on the windows means you’re lighting your interior entirely with caustics, which will take forever to clear up and is noisy as hell. And what for? The refractive effect of a window pane is negligible anyway.

b)
It is not a good idea to use refractive shaders on physically implausible objects.
Your windows don’t have thickness, they’re just flat planes, which basically turns your entire world into an enormous block of glass (as the glass surface is never terminated by a “back side”). This will result in a highly distorted look to the outside and won’t do your lighting any good.

For both aforementioned reasons and as Roken already said, use a glossy/transparent mix for “architectural” window glass instead.

4

Thank you very much! That helped a lot.

I figured out the problem with volume was caused by using a sun lamp. At the moment volume only works with spot lamps.

5

Sun and environment are positioned infinitely far away. World volumetrics is also infinitely thick. You either have to:

  1. World volume combined with local lights and no environment.
  2. Local volume box covering the scene where all lighting will work.

But I would still fix the glass. Lighting the room with caustics is just such a bad idea. Make the glass transparent to shadows, or better yet, make them thin glass planes combining transparency and glossy uvins fresnel, as well as combining another transparency using isShadowRay. Make sure the normals are pointing into the room (if camera inside), or you have to use 1/IOR for the backside fresnel. It sounds complex but should be more efficient to render.