Join Brian Bradley for an in-depth discussion in this video Working with irradiance mapping: Part 1, part of SketchUp Rendering Using V-Ray 2.
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- Because global illumination is such an important part of the rendering for visualization toolkit, we're going to spend this chapter examining most of the GI engines that are available to us in V-Ray for SketchUp. Indeed for the first two videos, we're going to focus entirely on using V-Ray's irradiance mapping engine, in order to test just how good it is at creating a basic global illumination solution for an interior shot. And we've chosen an interior setting to test all of the GI engines that we will be looking at in this chapter, because it presents by far and away the biggest challenge when it comes to getting a clean believable looking GI lighting solution.
In fact, we are making things even harder than they need to be here, by blocking light entry from our building's skylights. The plain green material that we are using will also add to the rendering difficulty, as it will help really show up any noise or blotchiness that is produced by the GI solution. With all of the default GI settings in place, V-Ray does provide us with a pretty decent global illumination set-up that can straight out of box produce some very nice daylight illumination. If I open up the options editor, you can see that with those defaults in place, irradiance mapping is set as the primary balance engine, whilst light cache is taking care of the secondary balances.
As in this video we really want to focus specifically on irradiance mapping, let's for now at least, set our secondary balance engine to none, meaning any balanced light that we see in the scene will be coming from the irradiance mapping engine alone. Indeed, if we take a render we can see that V-Ray runs through a number of irradiance map passes with each pass refining the solution and adding irradiance samples to the map being built as and when they are needed. Finally, we get a finished GI render from the system.
Now, because V-Ray defaults to having this show calc phase box checked, we get to see the irradiance map solution as it is being calculated. Meaning, we instantly get an opportunity to evaluate lighting and exposure levels in the scene, and if the lighting set-up isn't really working for us, we can quickly cancel the render, makes some tweaks, and then render again. Brilliant functionality to have available. Another very useful option that we see in the irradiance map controls is this show samples control. If I just put a check in that and again take another render, you can see that whilst we still get to see the irradiance map pre-calc as it takes place at the end of the process, rather than getting a finished GI render from V-Ray, what we actually get is a direct light only image that has had the location of irradiance samples as they have been placed in the scene by V-Ray overlaid on top.
This can be extremely useful when it comes to troubleshooting or refining how our irradiance map solution is working, because we can now see the areas in which the engine is deciding to place greater concentrations of irradiance points or samples which gives us the ability to make informed choices as to how we may want to tweak our irradiance map and/or lighting and material settings. Let's just make sure that we go ahead and uncheck that option before we continue. Whilst we have then made a start at getting a basic irradiance map solution in place, what we haven't as of yet managed to do is get a clean, high quality final solution from the system.
Something that we would be happy to use in a production render. In the next exercise then, we're going to spend some time working with the irradiance map controls that we see here in order to clean up the GI and produce something that we deem more acceptable as a final lighting solution.
- Locating V-Ray tools and features
- Using the RT Engine
- Creating daylight with V-Ray Sun and Sky
- Using image-based lighting
- Working with irradiance mapping
- Handling perspective correction in the physical camera
- Setting up a depth of field effect
- Creating and applying V-Ray materials
- Using fixed-rate sampling
- Color mapping
- Working with V-Ray proxies