Join Brian Bradley for an in-depth discussion in this video How our test scenes are set up, part 2, part of V-Ray: Control Color Bleed in SketchUp.
- [Instructor] Continuing on from the previous exercise, we have a dome light added to our scene and we have a Tech Sky op V-Ray Sky node added to it. The choice we have before us though, is how we want the background of our rendered images to be handled by V-Ray. You see, if we were to simply click the OK button here and exit the Light Editor dialogue, then the Tech Sky node as applied to the dome light is what will show up in the background of our rendered images. If we would prefer to use a custom map in the reflection/refraction background option in V-Ray's Environment Controls however, something that perhaps wouldn't affect our scene lighting then we would need to put a check in the invisible option found in the dome light controls.
Now, seeing as we have the Tech Sky node sitting in both locations at this moment in time, that is on the dome light and in our environment background options, then the end results, visually speaking, would be identical. Although there would be a potentially unseen difference between the two renders. A difference that we can take a look at if we do. Click OK to exit the Light Editor and then take a look at the Channels drop-down in the V-Ray Frame Buffer window. Now because we currently have no scene geometry sitting outside of our window here, we have an alpha channel that cuts nicely through to the SketchUp environment, making this set-up perfect for use in a compositing-based workflow.
With the dome light's invisible option unchecked however, as it currently is, if we jump back to our inside camera, and then take another render, what we see is that not only has adding our dome light to the scene not improved the lighting that we already had, but we have also now lost our alpha channel. This is because the dome light is now considered by V-Ray to be our virtual environment, or the surround for our scene. Because we will be wanting to do some basic compositing later on in the course however, we need to return to our outside camera and then after jumping into the Light Editor, set the dome light's invisible option to On.
After which, we can again click OK. Of course, we still have the problem as to why our lighting hasn't improved at this point. Well, this is simply because our GI skylight is of course, still active. And so, we now have both this and the dome light adding illumination to the scene. To remedy this, let's set the GI Skylight Multiplier Spinner to a value of zero, effectively turning off its lighting contribution to the scene. Taking a render from our inside camera now, gives us a slower rendering, but produces an image that has a much more believable and consistent lighting result.
The material set-up that we are using in the scene, if I just open up the Material Editor, is as simple as can be really, with the scene using a number of matte, as in non-reflective, V-Ray standard materials. Some of these are using simple gray scale values for their diffused color. On the walls we have a rough approximation of an antique cream, and of course, the villain of the piece, so far as color bleed is concerned, is the red material that has been applied to the floor. The GI setup that we will use for the vast majority of the time here is a jewel, brute force, and light cache system that lets us bounce plenty of light around our environment in a fairly quick, efficient, and physically accurate manner.
Finally, the color-mapping controls have also been configured in a way that is much more usable in a compositing workflow as compared, that is, to the default V-Ray for SketchUp setup. What we have here also much more closely mimics the current default and correct linear workflows that are set up in both V-Ray for 3DS Max and V-Ray for Blender. The only notable difference here being that we're using V-Ray for SketchUp's default Rhinhard Burn Value of 0.8 rather than one as it is in those other applications.
This setup does require that the display colors in SIGB Space button, found at the bottom of the V-Ray Frame Buffer window, is engaged as we are working. All in all then, what we have here is as we have said, a pretty basic scene, albeit with a few tweaks from default V-Ray for SketchUp settings. This should help us focus very much now on the subject at hand, which is, of course, the controlling of color bleed in our V-Ray renders.
- How light works
- The basics of color bleed
- Controlling reflectance using color values
- Setting up geometry with color bleed in mind
- Adjusting white balance
- Placing problem colors carefully
- Adjusting saturation
- Working with the GI Multiplier control
- Saving GI map files to disk
- Mapping colors
- Using VFB channels