From the course: 3ds Max 2022 Essential Training

Controlling spotlight parameters - 3ds Max Tutorial

From the course: 3ds Max 2022 Essential Training

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Controlling spotlight parameters

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- [Instructor] The other distribution type we will want to use very commonly for a Max photometric light is spotlight, which will emit light in a cone shape. I've got a dramatic, sort of theatrical scene set up here, in which I've got a key light, which is going to be a spotlight. I've also got a fill light and a couple of rim lights. Those are currently disabled, they're turned off. And so they're rendering as black in the view port here. Let's do an active shade rendering. What we have currently is a default photometric light for the key light. I'll select that, go to the modify panel. And it has the default parameters. 1500 candelas. The light shape is point. The distribution is uniform spherical. Let's brighten this up. We'll increase the number of candelas by factor of 10, increase that to 15,000. And now it's illuminating the surface of the sculpture pretty well. Let's switch over to lumens for a moment. I want to show you something. The lumens equivalent of 15,000 candelas is 188,000 lumens or so. Okay, so remember that. 188,000. Quite a high number. Now let's change the distribution type down here in the general parameters rollout. Switch that over to spotlight. Okay, we didn't see a lot change in our rendering. In the view port we now see a cone and a couple of concentric cones. And most interestingly, if we look at our intensity it's no longer 188,000. It's changed itself over to 4,270. Max did this in order to maintain the same approximate level of incident light on the surfaces. So uniform spherical distribution emits light 360 degrees horizontally and 180 degrees vertically in all directions. But spotlight distribution constrains the illumination within these cone angles. So the overall output is automatically reduced in order to maintain the same brightness over a smaller area. The candelas value is still 15,000. Only the lumens value actually changed. And that's one of the reasons I prefer to work in candelas whenever possible. In the distribution spotlight rollout, we have two important parameters here, hotspot beam and fall off field. Hotspot and fall off determine the spread and the softness of the edge. The hotspot is indicated in the view port by this inner yellow cone. I'll orbit around with Alt and middle mouse. So here's the hotspot cone. The illumination is going to be at full intensity within that hotspot cone. Then the illumination will diminish to zero intensity at the falloff cone radius. To get a sharper spotlight, we can reduce these cone angles. Let's bring the fall off angle down. As we reduce that, if we reduce it enough we will start to see the hotspot value change as well. Okay, well, what's happening here is that behind the scenes, Max is maintaining a minimum difference between the hotspot and the fall off. It's a minimum of two degrees by default. If I set the fall off to 18, then the hotspot is going to automatically be 16. And if I set the hotspot to 18, then the fall off is automatically going to be 20. We can change that behavior. We can go to customize, preferences in the rendering tab. We see hotspot fall off angle separation. If you want a super sharp edge, you can set that to a value of zero and click okay. And now we can set hotspot and fall off to exactly the same value. Set them both to 18. And now we get kind of a limelight effect of a super sharp edge. With hotspot and fall off both set to the same value, there's no variation in intensity across the field or across the area illuminated by the spotlight. And for that reason, if we switch our light distribution type back over to uniform spherical, we actually did not see any change in the illumination on our subject. So Max has set up to try to maintain that regardless of the distribution type you choose. And again, it does that by changing the overall intensity and lumens. I'll set that back to spotlight. Okay, the effect I want to achieve here is of a soft spot. So, I can reduce the hotspot, make that smaller. Bring that down to 10 degrees. Now I've got a nice, soft edge there. But I don't have soft shadows. The cone angles do not affect the softness of shadows. Also the cone angles don't affect the softness of the lighting, known as suffusion. We're getting a decay effect over the radius, but the actual light is a point light source. It's a very hard light. The cone angles also do not affect the decay of intensity over distance. The 3ds max photometric lights always conformed to inverse square law, also known as quadratic decay. And this is physically accurate. The intensity of an ordinary light source decays with the inverse square of the distance. But a real spotlight has a lens or a reflector to focus the light into a collimated beam. And that reduces the rate of decay and extends the light to a greater distance. Unfortunately, the max photometric light cannot fully simulate the optics of a real spotlight. We can make the rate of decay greater with this far attenuation feature, but we can not reduce the rate of decay to simulate a collimated beam. However, this can be achieved with the Arnold lights lens radius parameter, which I covered in my course "3ds Max: "Rendering with Arnold." The photometric spotlight does have a mechanism to achieve suffuse or soft illumination and soft shadows. And that's just simply the shape of the light. For a spotlight, the most intuitive choice would be a disk. And set the radius to, let's say 10 centimeters and now we're getting a nice soft edge to our shadows. And we can finally turn the other lights back on again, which I've got those disabled. So I can select this one here. That's my fill light. In the light properties, turn it on. Here's a rim light. Turn its light properties on. And then maybe finely adjust the overall intensity of the spotlight. Re-select that and ring it up to candelas value of 30,000. And now we've got a nice aesthetic rendering here with a three-point lighting setup. That's how to set up a 3ds Max photometric light with spotlight distribution.

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