From the course: 3ds Max 2017 Essential Training

Adjusting light distribution - 3ds Max Tutorial

From the course: 3ds Max 2017 Essential Training

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Adjusting light distribution

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- [Voiceover] Another really important parameter of a light is its distribution pattern. What we're seeing here now is a uniform spherical distribution pattern and that means that my light is going to emit illumination in all directions equally. For this dining room lamp, I might get better results and I might be able to control it better if I use a different distribution type. I've got a little light here that's inside this lamp and we can select that, go over to the Modify panel and in the general parameters is the distribution type here and it's defaulted to uniform spherical. Let's see what that looks like if we render it. I'll go to the perspective view and right-click in there to active it and we'll do a test render with draft quality settings in the ART renderer and we've got a little bit warmer color here. I've previously set this to have a color temperature of 3200 degrees and the camera is set to 3600 degrees and so that's why this is looking kind of warm. This is a, once again, spherical illumination pattern. It's sending out light in all directions equally. Cool, now I could cancel that at any time if I want to, but I'm just gonna let that finish until it reaches 20 decibels. My rendering at draft quality is finished, it took about 30 seconds or so, and that is once again the uniform spherical distribution type. I'll clone that rendered frame window so we can compare the results after we change the distribution type. Go to our viewport and select that light if it's not already selected and then change the distribution type. In this case I'm gonna use a spotlight distribution and that'll allow me to control the spread very intuitively and interactively. Switch that distribution type over to spotlight and I do want to mention, by the way, that if you're using any shape other than point, then you can't use the spotlight type. In other words if I had previously gone down here and chosen sphere or cylinder or something like that, then I would not be able to choose the spotlight distribution type here. Spotlights only work with the point shape. Cool, so we can see here now that we're getting just a little pool of light there and we can play around with how that light kind of spreads and the way that we do that is by adjusting the hot spot and falloff here. The hot spot is the center cone, we can click and drag here to adjust that, and within that center cone, the illumination will be 100% and it will fall off until it reaches that outer cone or that falloff radius. I can increase the falloff to a very high number, like almost 180, crank it up to like 179 or something like that and that's gonna give us a very soft look here. We have a very small hot spot and a very large falloff. It's gonna give me a super soft illumination pattern. Let's see what that looks like. With that perspective view selected, we can do another rendering and that didn't take very much time at all and that's because we have a very small distribution pattern here. It's not illuminating much of the scene so there's not much to reflect to the rest of the scene. We can go back here and play around with these values once again and let's look at this in perspective. If I give it a much larger hot spot, then we will get a different distribution pattern, it'll look different. So we'll go back to our renderer, click in there and here you go. You can see that now the difference is pretty clear between the spherical distribution pattern that sends light equally in all directions and a spotlight distribution pattern in which we have a bit more control. We can actually say we want less illumination here around the edges of the scene and this would be as if we had instead of, for example, like a compact fluorescent in here, maybe we have a halogen lamp that has a reflector inside it and it would focus the light a bit better. Notice also, by the way, that when we choose a spotlight distribution, it changes the overall amount of illumination. We can go back and look at that, scroll down into here. Here's our intensity and notice that as I change the hot spot and falloff, the number of lumens is changing here. What 3ds Max is trying to do here is to preserve the amount of illuminance at this point that's in the center of that falloff radius and as I adjust these radii here, it's dialing the number of lumens up or down to try to keep the luminance here constant. But what I find is that if I adjust the hot spot or falloff, I actually need to adjust the luminance values manually as well. Let's say I give this a hot spot of maybe 90 degrees and then I might want to increase the number of luminance values here, maybe crank that up to like 1500 and that's going to be a lot brighter and we'll do another test render. Here we've got 1500 lumens with a spotlight distribution and here we've got 1500 lumens with a uniform spherical distribution. So you will have to play around with this until you get the exact look that you'd like. Maybe I'll knock this down to 750 and do one more rendering. Alright cool, so I haven't adjusted my exposure. Of course if I needed a particular number of lumens or a particular pattern of distribution here, I might need to adjust the exposure accordingly. Last point around this is that in the distribution type you can also select photometric web and that's if you have a web document or a photometric definition of the light and you can actually download that from a light manufacturer and if you choose photometric web here then you can select a file and make the light distribution pattern match an existing real light in the real world. Again, you'd have to have that web file, you'd need to download that from the manufacturer. Cool, so switch that back to spotlight and go back to where we were. That's a little bit about how to work with the light distribution pattern to get different effects.

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