Prism and laser - no caustics!??

[nuno1980]

Hi.

I have OR 1.5 demo.

Scene:
-Laser (blue)
-Prism (dispersion with 1/3 and IOR 1.5)

Realistic is good using LuxRender (bidirec-MLT) for Blender running CPU only:
See image

In OR with PMC kernel setting default except rejects 10k, caustic blur 0.0 and parallelism 1:
No caustics?! - it seems unrealistics...


Prism hidden - it's realistic.


NOTE: current OR doesn't have "fog volume" support until new OR 2.0.

Therefore, should fix soon my issue (maybe 2.0).

Download "Prism demo" OBJ (laser IES included) in bottom.

[nuno1980]

OOh. I forget wireframe...

wireframe about ball light is for laser

[nuno1980]

Do you confirm my issue??

[FooZe]

Hi Nuno,

I have tweaked the light source and setup all the materials (see attached zip).

Here is the render after some time:

The most important changes were to the emitter. It's important in octane to make emitting surfaces as low poly as possible so I made it a plane.
Also, a bar works better than a dot for this (at least this is what I remember using in physics class ).

I have added a slight fog - this DOES work in 1.50

I left in 0.010 caustic blur, this is not enough to ruin the dispersion effect, and helps show the caustics a lot better/quicker. Parallelism was changed to 1, max rejects unchanged at 500.

Hope this helps.

Thanks
Chris.

[nuno1980]

Ok. I want dot light (= laser). But I can appear caustics from bar light horizontal, using caustics blur 0.0.

How do I enable fog volume?

[FooZe]

The fog is created by a cube surrounding the scene that has a specular material applied with the following settings:
1) Index 1.0
2) 0 reflection
3) full transmission
4) Scattering Medium with enough scattering to generate the amount of fog you want. (So tweak the Medium's Scale attribute to dial in more or less fog.)

It is important to note that you cannot have the camera inside this fog cube or it will not work. Note how the material picker will always choose the fog cube because that's what is in front of the camera. If you want to pick the prism or other materials in the scene you will need to right click when material picking.

Thanks
Chris.

[nuno1980]

The fog is created by a cube surrounding the scene that has a specular material applied with the following settings:
1) Index 1.0
2) 0 reflection
3) full transmission
4) Scattering Medium with enough scattering to generate the amount of fog you want. (So tweak the Medium's Scale attribute to dial in more or less fog.)

It is important to note that you cannot have the camera inside this fog cube or it will not work. Note how the material picker will always choose the fog cube because that's what is in front of the camera. If you want to pick the prism or other materials in the scene you will need to right click when material picking.

Thanks
Chris.

I have done but you choose to create box (rectangle or cube). Thank you!

My case is very hard for PMC kernel due to the dot or point light source - to appear hardly "sharper" caustics. But it has "new" caustic sampler, for iray or Thea Render...

[nuno1980]

NEW EVGA GTX 580 with 3GB edition (EVGA GTX 480 died to RMA -> new GTX 670 but I'm not interested 670 due to worse CUDA optimization)


New OR 2.02 demo but still max 256k-sample.


132k-sample and no caustic blur.

I want 2M-, 4M- or unlimited sample for newer version of OR, ok?

[nuno1980]

@FooZe or moderator: please should answer my question (my previous post).