The sampling rollout

- In this penultimate video for the chapter, we're going to take a look at the controls found in the sampling rollout of the V-RayLight. And so with our selected in the scene, let's go ahead and open up that rollout. Now we have already noted in the course that one of the brilliant things about working with V-RayLights is the fact that we don't have to worry about a lot of the options that have over the years, plagued lighting ATIs in 3ds Max, such as needing to understand the intricacies of shadow maps versus raytrace shadows, area shadow side, shadow map resolution and so on. What we do have in the sampling rollout, though, a couple of options that can be used to make tweaks to our V-RayLight, should the current scene or project require it. And by default, the truth we have immediate access to are the shadow bias and cutoff options. So what do these do? shadow bias is a setting that can be used to move a shadow either toward or away from the shadow casting object in the scene with lower values, pulling this shadow toward it and higher values, pushing it further away. If we push too far though shadows can leak and start showing up in places where they really shouldn't or even detach themselves from an object altogether. And so they is a use with caution type control. If we, for demonstration sake, then set a value of one centimeter in here and then take a render. You can see as I can compare to earlier renders from our history list, the shift that has occurred in the shadows with this extreme value, starting to create some of the problems that we have already mentioned. In certain situations though, where we may need to cheat a little bit with our shadows in order to improve a shot, then it is good to know that we do have a little bit of leeway available as regards to this particular aspect of shadow behavior. Cutoff on the other hand is a threshold that affects a light's intensity setting, stopping the light from effecting services. Once intensity falls below a specified value. Why would we need such a thing? Well, one of the big problems encountered when creating CG lighting tools in a renderer is the question of just how far you go in terms of copying real world light behavior. Because obviously the more realistic you try to be with the physics, the more computing power you are going to need, mostly because the inverse square law actually means that light energy or intensity never for all intents and purposes reaches absolute zero, but can instead be set to go on reducing forever and ever more pretty close to it. What the cutoff setting does then is create a fixed point or level of intensity below which light hitting a surface will no longer be computed. This can come in very handy indeed in scenes that have lots of lights in them, where we might want to limit the effect of set lights to a fixed distance. In essence, adding attenuation, or maybe we want to reduce computation. And those rendering time, wherever lights impact on the scene will now be negligible. Larger values in this control will limit the lights effect to a smaller area around the light source. Whilst lower values will increase the range with the default being 0.001. Do bear remind though that this parameter is not available when the renderer is set to V-Ray next GPU, the subdivides option that we also have in the rollout isn't available by default, because most users don't typically need local control over a lights subdivision values. This being the parameter that controls the number of samples used to compute the lighting locally. Lower values here as with V-Rays main image sampling and GI controls creates more noise, but will render faster. Whilst higher values will produce smoother results, but can also take longer to render. Again, this parameter is not available when the render is set to V-Ray next GPU. To activate this option, we will need to enable the use local subdivs parameter found in the V-Ray tab and Global DMC roll-outs of the render setup dialog. Noting that the actual number of samples used by V-Ray will also depend on the settings, found in the Global DMC rollout with the UI set to use advanced mode. Whilst not really needed by the majority of V-Ray users on the majority of projects created by them. The fact that we have access to and now know a little bit about the options found in the sampling rollout could in some scenarios be a potential project saver.