Join Christos Obretenov for an in-depth discussion in this video Setting up an object as an emissive light, part of Pixar's RenderMan Essential Training.
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- So we've got our mesh lights set up in the scene, and let's do just a quick render, before modifying anything about it just to see what that did. I mean, we created this sphere into a mesh light, but before we do that, let's get rid of our environment light. We don't want to see it because we won't know what is what. It'll be sort of competing. We'll add it back in later, so I'm going to select, the environment light in our outliner, that's our dome light with the full moon on it. We're going to hit control-H, it's gone. So the only light in this scene should be that mesh light, let's see if that is the case, so I'm going to kick off an IPR render, and it is gray, and we can't see much, but it is working, because we turned off all other lights, so if we look at our other renders, that's what it looked like before.
This is kind of noisy, full moon. But now we have just this NURBS sphere, and it's quite subtle, but it's certainly giving off light. So let's play with it a little bit. I've still got my IPR going, so I'm not going to stop and start it. I'm just going to go into my RMSMeshLightShape. I'm going to keep this window on top, and here we see we have exposure, color temperature, and a few other settings. So, first of all, exposure, that will just take it up and down, so let's take it to 10. So now we can see it really, kind of crank out, and if we took a look at bookmarks on our camera, I'm going to move that over.
I'll keep those down here again. If I go out, now remember, we got rid of that environment map. So we can see this nice, subtle lighting, and if I want to bring that exposure up, you know, I can really crank it, so it's getting quite noisy, but you know, at 16, that's kind of our only light source that's illuminating this scene. Now it's creating shadows down here, shadows in here, and of course it's noisy, but that's okay. If we did a final render we would get rid of that. Remember we're in the Path Tracer right now.
So that's pretty cool, we just created, like, this one light source is creating like, moody light, and if you remember in the still life scene, we had that on the candles. We'll take a look at that when we dive into that scene with the materials. But now we can sort of balance it out, now that we know it's working. Let's make it sort of, warmer, yellow, maybe a de-saturated yellow. We can bring in some orange. Now by default there's this color temperature of 5500 kelvins I believe. That sort of tints it a little bit warmer. If I put it at -1, it just turns off the color, but we can leave it at the default 'cause it gives it, sort of just a slightly warmer tinge.
Makes it look less CG. Let's make it a little bit more orangey, more towards yellow, but you can play with that. Just gives us a nice subtle effect. So let's bring back our environment light now, so I'm going to go to the outliner, I'm going to turn it on, and it didn't really seem to affect it, so sometimes you do have to stop and restart the IPR render if you're like, taking geometry and moving it around. Or turning stuff off and on, so if I stop and restart that, now we got that in.
So now, what we can do is we can just sort of, balance those lights out. One way to do it is just to go to each one and play with the exposures, but another way to do it is in the RenderMan menu, there's this really cool thing called Lighting, so let's bring up Lighting, and that's the Lighting panel. And I'm going to expand it a little bit, so we can see it. And if I click on defaultLightSet it takes a look at all the lights in the scene, and if you have light sets it gets more complicated, you'll have more sophisticated setup here, but this just basically shows all our lights here.
The colors, the exposure, it's just a handy panel. And we'll use this later on in the course, we're just going to introduce it here, and we can sort of tune our lights in here. So we can do the exposure for both of those, and we can solo them. So if I just want to see the mesh light, I can solo it. I don't have to turn it off and on in the outliner, remember I had to do that before? I can solo just the environment light, I can uncheck it. And I can balance them, I can say, mesh lights, you know, we're pretty happy with it, but we might want go down to 15, just to give it more subtle, and then the exposure, I might want to take it to -1, or -2 on that moon map, just to make it even darker.
So you get the idea, you can sort of, play with it in that way there. And imagine you had 10 or 15 lights in the scene. I mean, two is not that big of a deal, but this is a handy panel to make those changes and of course, you can change also, the color of the lights, right in here. You don't see that from the mesh light, 'cause that's a different kind of light, but for all environment map lights and area lights, like we saw in our last movie, you can do that in here. So I'm fairly happy with that, I'm going to go back into the scene, and I'm going to go back into a closer camera view, and I'm going to just stop and restart the render because we changed that view.
And you'll notice before, that light was kind of faceted, so that's why I wanted to stop and restart it. So now that we have this set up, the lights are balanced, we're ready to add the glass back onto the light, and we're going to take a look at some of the refraction, and that's where we'll compare the Path Tracer to the VCM, so now is a great time to finish off this movie. In the next one, let's add the glass in, and let's put those materials in, and do some more rendering with it.
- Generating your first render in RenderMan
- Using interactive progressive rendering (IPR)
- Working with AOVs
- Rendering with different integrators, including the path tracer and bidirectional VCM
- Setting up a scene with mesh lights
- Adjusting Max Path Length and other render settings
- Rendering materials
- Lighting in RenderMan