Join Brian Bradley for an in-depth discussion in this video Using the brute force engine, part of SketchUp: Rendering with V-Ray 3.
- [Instructor] In this exercise we're going to take a look at the last of V-Ray's GI options this being the Brute Force engine. Let's jump into the Asset Editor then so as to make sure that Brute Force is set as the primary ray option and then to follow the pattern of our previous exercises, we can also disable the secondary bounce engine by setting this to none at least for now. Now, one thing I still like to point our to students at this point is the fact that in times past very few seasoned V-Ray users would choose to make use of the Brute Force engine on an interior render such as this although this is changing as render speeds continue to improve.
Unless there is a very specific need, however, such as having lots of detailed geometry in a scene, the fact that Brute Force can be both slow to calculate and extremely hard to clean up on interior renders it still makes it a bit of a use at your peril kind of option unless you have lots of rendering power at your disposable that is. If we look at the control set that comes with Brute Force we can see that it is as easy to work with as possible given that in the primary ray slot it has no control settings at all. It literally is a turn it on and render solution with all of the quality options being handled by V-Ray's sample controls.
If we take a render of the scene as it currently stands, we do though perhaps see why this particular GI method isn't always first choice for use on an interior scene for many artists seeing as we have even whilst using medium quality settings a lot of noise in the render and this has taken quite a while to complete. One thing that could perhaps help would be to again make use of our sky portals and do let's unhide that layer, enable all of the relevant settings, and then go ahead and take a render.
What we get does show that we have improved our scene although we have of course taken quite a jump in terms of our already and longer than usual render times. Because we are essentially talking about a straightforward noise problem in our image though, cleaning things up is as simple and straightforward as cranking up the quality settings. In the raytrace rollout then, let's set our max subdiv's value to 50, switch the AA filter over to triangle and then take another render.
And what we see once done is that we have cleaned up a lot of the noise that was in our image although we have again taken quite a hit in terms of our render times. Given the nature of how the Brute Force system works though this is simply a drawback that we may have to learn to live with, although we do of course need to keep in mind here that we are forcing an artificial test situation on the Brute Force engine given that we would never really want to try using it without having a secondary bounce engine enabled as well. You see, Brute Force, just as with the irradiance map system only adds a single bounce of light to our scene whilst used in the primary ray slot.
Let's see what happens then if at this point we go ahead and add a secondary bounce engine to the mix. As this is an interior, we will again make use of the light cache system and keeping all the defaults in place, we can take another render. Well, you no doubt noticed two very interesting things happen then. Firstly, we get a lot of extra illumination added to our scene and secondly, we have quite seriously decreased our render times. This is because the image sampling engine in V-Ray is now no longer having to work quite so hard in order to clean up noise in the darker areas of our render.
Let's save this image to history and test one final configuration by setting the secondary bounce engine to Brute Force as well. Now, as set as a secondary ray engine we do get a GI depth control with Brute Force which in this instance handles the number of times that light rays will bounce in the environment. A value of five should do nicely here. If we again take a render, and make a comparison of what we have, we see that although we have made our noise problems a little more obvious, we have produced what to my eye at least looks like a light simulation that is behaving in a more natural-looking manner, although the price for this is that our render times have once again jumped right back up and given that the differences we are seeing here are very subtle indeed, this may well be a price that we deem to be too high.
Whilst Brute Force then is probably not always going to be our first choice of primary bounce GI engine in some settings, we have hopefully seen in this exercise just how easy it is to work with and how much quality it can produce, especially so if we should have the rendering power available to take advantage of it in both the primary and secondary ray slots.
- 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