Volumetric light just from single elements


I’m trying to create a particular scene. I have a box modelled that should be lighted the normal way, but when it opens it should show rays of light from the inside.

All I found online are tutorials on how to use the volumetric light using a volume scattering. This creates a foggy environment but not what I wish to achieve. I’d like to use an HDR image to light the scene with some polygons emitting light placed in the right spots.

The environment isn’t visible and doesn’t affect the scene if the volume scattering of the world is active, while it affects the scene just outside the cube that defines a volume scattering as an object. Basically, it looks like a cube of mist. Is there a way to have rays of pure light emitted from a box (as if the box was enchanted with magic), but at the same time being able to thee properly the outside of the box?

Basically what I’d like to do is assigning a volume scattering just to some of the lights… or maybe using a totally different method…

Thank you for your help!!!

Hey, I put together a simple scene trying to create the effect you described. You’ll need the beta of Blender 2.8.
box_example.blend (628.6 KB)

Hello spiegelball,

Thank you for this.
You actually “forced” me to use Blender 2.8 that’s a very good thing!

The result is amazing, but not quite what I was looking for.

Basically the light is perfect, but the box is lit by that light. What I’d like is for the box to stay for example on a plane and lit it with an hdr image. I tried to play a little with the file {I have to admit… I didn’t know where most of the commands where… is so new}, placing a plane under the cube and adding an hdr image to light the whole scene. The result is quite weird. The gap between the box and the floor is lit with a very strong light and the cube is quite unrealistic as it seems rendered by the old Blender Render engine.

Do you know if there is a way to lit the scene normally {maybe placing an hdr image} and then showing just the rays of light emitted from the box (maybe the light source can be a polygon that emits light)?

This is a quick render of what I tried to do…

I managed to achieve something similar {but not quite}.
Basically I rendered the elements twice on two layers, {one with and one without volumetric light}.
Then in Photoshop {after effect for the video} I will add the volumetric light to the normal using a hard light blending.

I don’t like the fact that the elements hit by the light are grainy.

This is the effect I’d like to achieve

I’m adding some renders and a .blend file hoping someone can help me. Would be nice being able to do this without post production.

Basically the .blend file has the elements to be rendered in the first layer and the elements with wolumetric light in the 11th.
I made two separate renders…
I also tried to use a render pass to render just the light rays but volumetric light cannot be rendered as a pass…

Thank you!

volumeScatter1.blend (1020.0 KB)