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Time now to work at refining the irradiance mapping solution that we have created so far. As we can clearly see, what have at this moment in time certainly doesn't work as a final production render solution. To make a start at improving matters here, one thing we can do is to turn on our currently disabled V-Ray rectangle Light. So we'll go up to our Window menu, and I am just going to pull up the Outliner for ourselves, and you can see our Sky_ Portal here, so if we just select it, we can get rid of the Outliner. Come over to our Attribute Editor, and we just want to put a check in the Enabled box.
We also want to scroll down in our V-Ray Lights options. We want to come down, in fact, to the Options section, and we want to work with this Skylight Portal option. Now essentially, enabling this will give the GI systems a portal or focus point that they can use to pull color and illumination information from our outdoor environment. This will help the GI system to really illuminate our interior in a much more natural way. From this, there are a couple of extra steps that we need to take, or at least one. If I, in fact, just enable Sky_Portal initially, if we save our current render, and if we take another one, you can see that rather than improving matters, we get a very strange result back from our render indeed. And this is because there is a little bit of a glitch in the way the skylight portal options are operating.
We just need to take another step to make them work correctly. So let's come back to Skylight Portal. In fact, if I just scroll up, and come to the Shadows rollout, you can see we can't access the Shadows option here, and that is what we really need to do. So if we just disable Skylight Portal, now we can enable Shadows, and if we come back down and Enable the option, and save that, and take another render, you can see, we get a much more pleasing result. And if we just get rid of that particular render, we can compare to our original, and you can see, we have made some definite improvements in the scene.
You can see, the illumination is much more believable, the colors are working much more as we would expect from an outdoor lighting scenario, and we have definitely gotten rid of some of this large blotchy noise, particularly in the foreground. Of course, we still have a number of difficulties that we need to work with to make this a clean and usable solution. We just go back to our Irradiance mapping controls. Obviously, one of the things that we could do would be to increase our Irradiance map's resolution. If we go up these presets, that is exactly what we would be doing. Of course, we could work with custom options, and set those in there for ourselves.
And while that is a perfectly viable way of working, we would increase our render times by quite a bit, and we would still need to work with other parameters inside of the Irradiance map controls to get a nice, smooth, and clean solution. Specifically, we would need to work with these subdivisions and interpolation samples options. Now, the hemispherical subdivisions is a parameter that controls the number of rays sent out from each of the irradiance map samples in the scene, so that hemispherical dome of rays that is cast from each of the samples.
The interpolation samples option really determines how many irradiance map samples get averaged, or blended together to create a smoother lighting solution. Now, working with either of these on their own will not really produce a usable solution -- not inside of our current version of V-Ray for Maya -- but what we can do is increase each of these to just get a little bit more quality in the scene. So if we up our subdivisions value to around about 125, let's set our interpolation samples to 50, and again, let's save our render, and take another one.
And if we compare what we have, you can see, we have definitely improved matters in the scene. We've cleaned up a lot of that large blotchy noise; not really made any difference to this small noise on the floor area here, but everything is looking much nicer at this moment in time. Now, we do have a little bit of a confession to make. It really would be a very rare occasion indeed where irradiance mapping was chosen to provide a suitable GI solution on its own. See, irradiance mapping, as we have stated, gives us only a single bounce of light.
Now, whilst that is far better than a direct only lighting solution, it still is not an accurate representation of light distribution in the scene. For that, we would need to enable our Secondary bounce engine, and in an interior render such as this, the preferred option would definitely be the light cache system. So let's take a look at how things would look if we just go and enable Light cache, and take all of its default settings, and of course, save our render, and have a look at what we would get. Now, instantly you can see that we've made a huge difference to the illumination level in the scene.
There is a lot more light being bounced around this environment, and because of that, our noise problems don't look as bad as they did. We haven't really done anything to clean them up, but they just blend in a little bit more with the surroundings, because of the amount of light being bounced around this environment. Of course, we don't have much in the way of contact shadows at this moment in time. If we wanted that, we would need to come up in our Indirect Illumination controls, and turn On this Ambient Occlusion option. That would give us much more in the way of contact shadows in the scene. As we have seen, creating a GI solution using the Irradiance mapping engine in the Primary bounce slot can be a very quick and easy process.
Of course, adding Light cache into the scenario definitely improves things in terms of the level of illumination, and if we were to add V-Ray image sampling controls and DMC sampler controls into the mix, we could clean up the noise in the scene very nicely. Time to move on, now, to looking at our next GI engine, and we are going to focus this time on the Light cache system.
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