Join Aaron F. Ross for an in-depth discussion in this video Approximating direct sunlight, part of 3ds Max: Advanced Lighting.
- (Teacher) To provide the direct illumination from the sun we can approximate that using a photometric light. In my perspective view I can't really see much because I am in a shaded view. I will press "F3" to go into wire frame and create a photometric target light. Go to the create panel, to lights, photometric. Click "target light". And in the top view click and drag to create the light and its target.
I am pointing the target toward the architecture here. Release the mouse and then right click to exit the tool. With the light still selected go to the modify panel. And we can see we've got a target distance listed here. I previously experimented with the light position so I know exactly where I want it to be. So, I am going to select the light and not its target. Go to the move tool, and in the transform type in area down here, I am going to set the light position in X to be negative 127 meters.
Negative 127. Now it is pretty far out there. The Y value, set it to negative 417. And then finally, the Z value or elevation here I want to be 120 meters above the horizon. And now that light is positioned pretty much in the same place that the sun positioner was and it is just inside our environments sphere.
If the light itself were outside that sphere then the sphere would cast a shadow and the light would not be able to reach into the window. With the light still selected, go back over to the modify panel and we see our target distance is less than 450 meters and that is because we are just inside that sphere. We need to use that number, actually, to set the intensity of the sunlight. Over here we've got the intensity values. We can set it by lumens, candelas or lux at a certain distance.
And this is the mode we want here. Choose "lux at" and then set the distance to be about the same as the target distance. Let's make it 450 meters. And then the intensity of the light at that distance is currently only 1500 lux. Select that and turn it way up to 70,000 lux. And that will emulate a strong light coming through the window. We can set our color temperature up here.
Instead of the default d-65, I'll set a custom kelvin value and we can see it is set to 3600. Let's make it 4800. It'll be an orange light relative to the background which has a color temperature of 6500. Finally, we have the distribution type and that interacts with the shape of the light. For the emit type, I'll choose "disk" and that will give me soft shadows depending upon the size of the disk.
If I use disk as the emit type, then I should choose "uniform diffuse" as the light distribution type because uniform spherical is not actually compatible with the disk and the renderer will actually default to uniform diffuse anyway. Uniform diffuse is a one sided illumination. So, it will only emit from one side of the disk. Okay and then we finally got our radius. And we will increase that up to three meters.
And we should get pretty nice soft shadows now. Okay, we've set up all of the parameters for our approximation of sunlight and we can go ahead and click "render production". And once again, here is a full screen rendering of our custom interior daylighting set up in which we are approximating the sunlight using a photometric light and our environment is coming from a piece of self-illuminated geometry. This gives us a lot more artistic control then the ART default physical sun and sky environment.
- Photometric lighting and gamma correction
- High dynamic range and exposure control
- Global illumination
- Exterior daylight
- Image-based lighting
- Atmospheric effects
- Geometric backdrops and self-illumination
- Hiding the background for compositing
- Interior daylight
- Studio soft lighting
- Importing photometric data
- Light and shadow exclusion
- Mapping light with Projector Map
- Lens Effects