LuxCoreRender Forums

I'm most accustomed to cycles, so I have a few questions.

One, how do I use normal maps? All I see is a "Bump" input on any shader I create.

Two, why do my glass materials not bounce any light inside of them unless I use a mesh with emission on it?

Three, in relation to the above problem, normal lights don't seem to bounce or scatter in my volumes until they hit something. I again have to use mesh lights in order to achieve the desired effects.

Four, I can't seem to figure out how to change the actual density of my volumes.

Five, I only have access to normal path tracing and bidirectional path tracing (CPU only for some reason for the latter). I'm unsure how to take advantage of things such as: ExPhotonMap, Instant Global Illumnation, and Distributed Path.

Lastly Six: Hair shading, wheeere do I even begin on that?

Here you can see that not only does the first glass ball not refract any light from the area lamp (set to laser), but that it also doesn't scatter through the volume until it hits anything: https://i.imgur.com/IlZnKgj.png

Clarification of these three problems would help immensely! Sorry if these are already answered, but I can't seem to find solutions in the documentation and would prefer an actual person to point me in the right direction. I wanna use luxrender going forward since I've seen substantially better results than cycles in the gallery.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm One, how do I use normal maps? All I see is a "Bump" input on any shader I create.

You load the normalmap via the image texture node and enable "Normalmap". This will turn the output of the image node into a bump socket which you can connect to the material's bump socket.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Two, why do my glass materials not bounce any light inside of them unless I use a mesh with emission on it?

I am not sure what you mean. Can you show an example picture (ideally upload the problematic scene as well)?

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Three, in relation to the above problem, normal lights don't seem to bounce or scatter in my volumes until they hit something. I again have to use mesh lights in order to achieve the desired effects.

Most of the time this is caused by an incorrect volume setup, e.g. missing interior/exterior volume settings on the materials or camera.
Having the scene would help a lot to find the problem.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Four, I can't seem to figure out how to change the actual density of my volumes.

In the homogeneous and heterogeneous volumes, a higher scattering scale means a higher density.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Five, I only have access to normal path tracing and bidirectional path tracing (CPU only for some reason for the latter). I'm unsure how to take advantage of things such as: ExPhotonMap, Instant Global Illumnation, and Distributed Path.

ExPhotonMap, Instant Global Illumnation and Distributed Path are things from old LuxRender, they have been superseded by the engines we have in LuxCore.

Instead of ExPhotonMap, you can use PhotonGI and enable the caustic cache (in the cache settings in the render properties).
Instead of the others, just use the Path engine.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Lastly Six: Hair shading, wheeere do I even begin on that?

Maybe the wiki helps, or the tooltips in our hair settings (in the properties of a Blender hair system).
https://wiki.luxcorerender.org/LuxCoreR ... ir_and_Fur
In general, you just use the regular shaders on hair, and you can use vertex colors and UV information to do things like a gradient from bottom to tip of a hair strand.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Three, in relation to the above problem, normal lights don't seem to bounce or scatter in my volumes until they hit something. I again have to use mesh lights in order to achieve the desired effects.

If you set your world volume here you should disable camera volume here Uncheck "Auto-Detect Camera volume" (if checked). Press X at the right of volume selection drop-list (after button "Show" and button "+").
Or else you'll get some very nasty image.

Is it possible to get lighting that's as accurate as BiDir without having to use my CPU? I'm playing with photonGI and stuff but it doesn't seem to produce as realistic of a result.

P.S Thanks for all of the answers!

B.Y.O.B. wrote: ↑Sat Oct 05, 2019 10:11 am

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm One, how do I use normal maps? All I see is a "Bump" input on any shader I create.

You load the normalmap via the image texture node and enable "Normalmap". This will turn the output of the image node into a bump socket which you can connect to the material's bump socket.

sdfdsf.PNG

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Two, why do my glass materials not bounce any light inside of them unless I use a mesh with emission on it?

I am not sure what you mean. Can you show an example picture (ideally upload the problematic scene as well)?

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Three, in relation to the above problem, normal lights don't seem to bounce or scatter in my volumes until they hit something. I again have to use mesh lights in order to achieve the desired effects.

Most of the time this is caused by an incorrect volume setup, e.g. missing interior/exterior volume settings on the materials or camera.
Having the scene would help a lot to find the problem.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Four, I can't seem to figure out how to change the actual density of my volumes.

In the homogeneous and heterogeneous volumes, a higher scattering scale means a higher density.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Five, I only have access to normal path tracing and bidirectional path tracing (CPU only for some reason for the latter). I'm unsure how to take advantage of things such as: ExPhotonMap, Instant Global Illumnation, and Distributed Path.

ExPhotonMap, Instant Global Illumnation and Distributed Path are things from old LuxRender, they have been superseded by the engines we have in LuxCore.

Instead of ExPhotonMap, you can use PhotonGI and enable the caustic cache (in the cache settings in the render properties).
Instead of the others, just use the Path engine.

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Lastly Six: Hair shading, wheeere do I even begin on that?

Maybe the wiki helps, or the tooltips in our hair settings (in the properties of a Blender hair system).
https://wiki.luxcorerender.org/LuxCoreR ... ir_and_Fur
In general, you just use the regular shaders on hair, and you can use vertex colors and UV information to do things like a gradient from bottom to tip of a hair strand.

You can actually see the glass problems in the image I have attached.

Cyro wrote: ↑Sat Oct 05, 2019 3:34 pm Is it possible to get lighting that's as accurate as BiDir without having to use my CPU? I'm playing with photonGI and stuff but it doesn't seem to produce as realistic of a result.

Not with Luxcore, I think. I like bidir too, and I think that's the only option to get beautiful images is to use bidir. All other options are mere trade-offs and are far less beautiful.
I wish we'd get bidir on gpu soon

Cyro wrote: ↑Fri Oct 04, 2019 5:15 pm Here you can see that not only does the first glass ball not refract any light from the area lamp (set to laser), but that it also doesn't scatter through the volume until it hits anything:

tldr; but there's a little tip: You have to put your camera outside of volume in which light is scattering. If you absolutely must have camera inside, then make lil box, and make boolean cut out of the surrounding scattering volume box. Or you can (though I can't remember if I tried that) make box with clear volume and give it higher priority than surrounding scattering volume.
Assign world volume.
Disable camera volume. It doesn't work and will give you an artifacts. I guess there might be some people telling you that you can actually assign world volume to camera volume. Trust them not! Trust me
Make sure your volumes has proper priorities assigned. In your scene that would be e.g. 0 for world volume, 1 for scattering volume, 2 for glass.

wasd wrote: ↑Sat Oct 05, 2019 3:49 pm

Cyro wrote: ↑Sat Oct 05, 2019 3:34 pm Is it possible to get lighting that's as accurate as BiDir without having to use my CPU? I'm playing with photonGI and stuff but it doesn't seem to produce as realistic of a result.

Not with Luxcore, I think. I like bidir too, and I think that's the only option to get beautiful images is to use bidir. All other options are mere trade-offs and are far less beautiful.
I wish we'd get bidir on gpu soon

I hope so too, though I can't seem to get photonGI to generate *any* global illumination for some reason. It worked the first time I did it, but I'm not sure why it's not doing it now. I've enabled "Add Light Tracing" "PhotonGI Cache" and "Indirect Light Cache" but I only get the direct lighting, no bounces.
Those settings: https://i.imgur.com/czc23Lg.png
BiDir Render: https://i.imgur.com/awTmnBW.png

Also I can't seem to get glass to have internal reflections with the above settings.
Example: https://i.imgur.com/l5X9DFB.png