Join Brian Bradley for an in-depth discussion in this video The progressive sampler, part of SketchUp: Rendering with V-Ray 3.
- [Instructor] Now that we are familiar with what image sampling or ray tracing in V-Ray is, and have grasped the basics of how the process works, we can perhaps start to see why the choice of sampling engine that we use on a project can become a fairly critical production decision. For this reason then, we're going to use the next few videos to walk ourselves through a quick overviews of the workings and controls available for each of the sampling engines in V-Ray, starting first of all with the progressive offering. As this is the default in V-Ray for SketchUp, getting started with it is as easy as hitting the Render button once we have our scene open.
The first thing we then see of course is the light cache precalc take place in the Frame Buffer window. Once that is done however, we see the entire image begin to progressively refine over the course of a number of passes. One big advantage to this type of rendering is the fact that we can see and evaluate our render right from the get-go without having to wait for the bucket system to complete enough of it that we can actually see what is going on. To take a look at the controls for the progressive sampler, let's open up the asset editor and jump into the Settings tab.
Now unlike version two, where V-Ray for SketchUp, we are, by default, given a very simple set of options for controlling image quality in our scene. We have a quality slider that if we expand the UI and look in the Ray Trace rollout, is tied under the Quality heading to this Noise Limit control. Indeed, if I just drag the quality slider around a little, we can see how this automatically updates the noise limit value, which is actually a really useful way for us to quickly learn how this noise limit works.
If we want faster renders with lower quality, then we simply increase the noise limit value, whereas if we want to produce very clean, almost noise-free renders, then we need to set this value down to around about the 0.005 mark which is typically recognized as a production sweet spot, giving high-quality renders within a generally acceptable timeframe. If we are a more experienced V-Ray user and so would like to have a little more control over the image sampling process, then we can easily switch the Ray Trace UI over to advanced mode, so as to gain access to things like the anti-alias filter being used as well as the shading rate and max depth values for rays in the scene.
An extra and oftentimes very valuable piece of functionality that we get with the progressive sampling engine is the ability to set a time limit on how long an image or a frame of animation can actually render for. Doing that is as simple as putting a check in the box and then setting the limit in minutes that we want to apply. We can even go down into fractional values if we want although just be aware that any values we use here tend to be approximate rather than microsecond-accurate.
Having said that, the higher the minute value we use, the more accurate V-Ray will probably be as it then has time to figure out the sample count that needs to be used. Another very nice feature that has been added to V-Ray's progressive engine in recent times is the ability to utilize GPU rendering in production with enabling that feature being as simple as flicking the switch, although one potentially big disadvantage to using the progressive system is the amount of data that it needs to store in memory, especially so when working with lots of render elements in the scene, something that can become even more problematic when rendering on the GPU given the limited amount of VRAM limiting GPU rendering with the progressive engine is the fact that renders calculated by the CPU and GPU versions can tend sometimes to look very different from one another, at least at the time of this recording.
Another drawback of the progressive engine is that when using distributed rendering, because of the continuous refinement that is taking place, the frequent communications between the client machine and the render server that is needed can somewhat reduce utilization of the slave machine's computing power. All of that having been said though, what we have in the progressive engine is a very powerful sampling solution that is more than ready for use in a lighting and rendering production pipeline.
- Gamma handling in V-Ray 3 for SketchUp
- Working with interactive rendering
- V-Ray light types
- Working with irradiance mapping
- Rendering animations
- Working with the V-Ray camera
- Using the Materials UI
- V-Ray FX tools
- Stereoscopic 3D rendering
- Using V-Ray objects