Join Brian Bradley for an in-depth discussion in this video Global Illumination explained, part of V-Ray 3.0 for 3ds Max Essential Training.
- The V-Ray renderer comes equipped with a number of extremely powerful global illumination, or GI Engines, that can help us recreate most any lighting scenario we may have in mind. If we just open up 3ds Max's Render Setup dialog, we can take a look at where these GI tools can be found, which is in the appropriately named GI tab. From here, we gain access to a number of different, and yet extremely high quality global illumination systems. The feature sets for these tools are robust, they are powerful, and they give us as artists the ability to easily switch between both physically correct and artistically correct approaches to our lighting setups.
They can be tuned to be fast enough for the most demanding of production schedules while still outputting high quality images for us. Or, the can conversely be set to the highest of quality settings, making content created with them indistinguishable from actual photographic material. Of course, what these systems ultimately do is remove an awful lot of the guesswork that would otherwise be involved should we have to work it manually trying to recreate realistic lighting solutions. Now for the benefit of users who may be somewhat new to 3D rendering, we should perhaps start this chapter with a brief overview of how global illumination works, something we can start to do by contrasting it to its CG lighting opposite, which would be local or direct illumination.
By default, adding CG lights into a 3D scene and then rendering without any GI systems enabled will give us only this localized or direct version of illumination. This is not, of course, how light behaves in the real world and is the reason why we need GI systems in our renderers, giving us as they do, the ability to simulate the physical reality of light, which in the real world, expends a lot of time, expends a lot of energy bouncing around the physical environments that we enhabit.
We can get a basic understanding of how global illumination systems mimic this behavior by taking a brief look at how light behaves in the real world. Once light is emitted from a source, it will travel along its emission vector until it strikes the surface of an object. At this point, a lighting phenomenon known as inter-surface reflection occurs, meaning that a portion of the incoming light energy now gets reflected or bounced. Dependent upon the amount of energy being output by the source, the light can actually bounce quite a number of times.
With each bounce, it will lose a little bit of energy. And, with each bounce, it will also pick up a little bit of coloration, inherited from the diffuse properties of the surface that it has so far interacted with. The end result of this bouncing around is that an environment becomes lit, with even the darkest nooks and crannies receiving some level of ambient lighting, even though they may be quite far away from any direct light sources. This simple sounding and yet extremely complex real world process is what global illumination systems try to mimic, giving us as lighting artists the ability to create scenarios and renders that contain extremely high levels of accuracy and realism.
We can even use V-Ray's GI systems to conduct basic light analysis tests that give Architects and Engineers a way of measuring how much illumination a given environment and a given set of light sources will produce. In V-Ray, this can be accomplished by means of the V-Ray Light Meter Tool. With that basic explanation of light behavior and global illumination fixed in our minds then, we're ready to move on and examine one very specific aspect of V-Ray's GI implementation.
This being its use of both primary and secondary bounce engines.
- 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.