Join Brian Bradley for an in-depth discussion in this video Using irradiance mapping: Part 2, part of V-Ray 3.0 for 3ds Max Essential Training.
- Having already created a basic irradiance mapping solution, we are in this video, going to work at refining what we have. As you can see in our render, taken from where we left off in the previous exercise, we currently have a very blotchy GI solution that really doesn't work as a final production quality lighting set up. The question really is how can we go about improving things? Well, one thing we could do is give the irradiance mapping engine a helping hand. We can do this by making use of a sky portal in the scene.
In the layer explorer then, let's unhide our "Sky Portal" layer, and after selecting the now visible V-Ray light, make certain that it is both enabled and set to function as a sky portal. With this option turned on, the color and multiplier parameters of the V-Ray light are actually ignored as the light will now take its color and intensity values from the environment setting behind it. In fact, because we have no real geometric object sitting outside of our room, we can cut down on the amount of ray casting that the V-Ray light has to do by also enabling the "Simple" portal option.
With that done, let's add our current render to frame buffer history list, and take a second render. If we now compare the two by adding our initial render to channel A in the frame buffer, we can see as we switch between the two images, that we are indeed getting quite a different result, both in terms of illumination levels in the scene, and the quality of our irradiance mapping solution, although we still do have to admit that we are quite a ways short of having a nice, clean lighting solution. We can see on the window wall that we have some very obvious splotching coming from the irradiance map, and we have of course, with the addition of the sky portal, introduced a ton of fine noise or grain to the render.
Now to deal with the first of those problems, we could increase the resolution of our irradiance map Remember, we are still only making use of the low preset that we set up in the previous exercise. The problem with going back to something like the default high preset, is that we would add significantly to our render times whilst in all honesty at the same time, not making any real difference to the splotching that we are seeing. Sometimes a better approach is to try and work with the two parameters that we have here: hemispherical subdivisions and interpolation samples.
The hemispherical subdivisions parameter controls how many rays are traced from each of the irradiant samples that V-Ray has placed in the scene, whilst the interpolate samples option determines how many of those irradiant samples get averaged or blended together at render time. Well, let's do a quick test using each of these controls. First of all, after adding our current render to the history list, let's bump up our interpolation samples, say to a value of 100 and again, take a render.
The final result, if we just compare this to our previous image, shows that we have indeed, cleaned things up quite a bit. The problem is that as we are performing an averaging operation here, we are losing detail in the scene. As I wipe between the two images, we can clearly see that contact points or occlusion shadows have become much less obvious. We did say though, that we could also try working with our hemispherical subdivisions option. So with our interpolations value left at 100, let's really bump up our hemispherical subdivs by setting those to a value of about 200.
Save what we have to the history list, and again take another render. Now in this instance, our render time does go up by quite a bit, which isn't surprising given that we are now theoretically calculating a much more accurate lighting solution. The more rays we use, the more accurate our lighting should be. A quick comparison between our two images, however, reveals that this parameter change hasn't made any significant difference to the look of our final image. Seeing then as we already had a fairly clean-looking GI solution, and given the fact that we can add extra ambient occlusion to our renders using advanced mode in the global illumination roll out, let's drop our hemispherical subdivs value back down to something like 50, and move on instead to tackling the fine noise or grain that was added when we enabled our sky portal.
Before trying to clean this up using any kind of brute force sampling, however, we do need to keep in mind the fact that irradiance mapping is only adding a single bounce of light to our scene. This, as you will recall, is not how light works in the real world. To mimic that behavior, we really do need to enable one of V-Ray's secondary bounce engines. And in an interior setting such as this, the preferred choice would almost always be the light cache system. Let's go ahead and enable that then, and leaving all settings at default, take another render.
What we get now shows a huge difference in terms of illumination levels in the scene. This in turn, is also helping us with the splotching that we were getting from our irradiance map-only solution. To add a couple of final tweaks, let's select our sky portal, set its sampling subdivs to a value of 64, and then in the global illumination roll out of the render setup dialogue, turn on expert mode in the UI, and enable the ambient occlusion option that we spoke about a little earlier.
A final render shows that we have pretty quickly created a clean-looking GI solution using irradiance mapping as the primary bounce engine. Along of course with more than a little help from light cache, working in a secondary bounce role. Perhaps the next logical step in our course then, is to go and take a closer look at the light cache system itself.
- Using the new UI elements, Quick Settings, and revamped Frame Buffer
- Understanding color mapping modes
- Adding V-Ray light types
- Working with the V-Ray Sun and Sky systems and dome light
- Using irradiance mapping and light cache
- Working with diffuse color maps
- Making reflective materials
- Creating a translucency effect
- Using the new SSS and skin shaders
- Ensuring quality with image sampling
- Working with the adaptive subdivision engine
- Controlling the physical camera
- Working with FX tools such as VRayFur and VRayMetaball
- Stereoscopic 3D rendering
- Using Render Mask
Skill Level Intermediate
Q: This course was updated on 02/02/2016. What changed?
A: We added tutorials on the new 3ds Max camera tool, which replaces the defunct V-Ray Physical Camera. The author also includes a method for creating a V-Ray camera via scripting.
Q: This course was updated on 04/19/2018. What changed?
A: New videos were added that cover V-Ray 3.1 to 3.3 updates.