Join Adam Crespi for an in-depth discussion in this video Creating the Daylight system and positioning the sun, part of Rendering Exteriors in Maya.
Light and materials go hand in hand. One you've got materials applied in a scene, the light can really work as it should. Inversely, if the materials aren't good, the lighting isn't going to show. I've got my scene all done with Mental Ray Materials as far as I can see. I think I've got all the objects assigned with an MIA Material X Passes, and I've adjusted the parameters accordingly to bring those rich materials to life. My plants are all converted from paint effects to polygons and I've gone through them and optimized the materials putting on Mental Ray Materials and using the existing shaders and texters.
As part of the conversion process, my plants unlinked from my landscape layer, so I added them back on by selected them right clicking on my landscape display layer and choosing add selected objects. I'll turn off the plants for now, and I'm ready to create my daylight system. The daylight system is really fantastic for exterior renderings, because it is well, daylight, as you'd think. It's got a physical sky, a sun, and an exposure on the camera, so that the camera sees the sky. The sun is lit and participates with the sky and everything is seen through an exposure, that way it's tone mapped and we get the right luminance in our scene.
I'll start out by creating my daylight system. Clicking on the render settings button and in render settings, jumping over to indirect lighting. I've already turned on Mental Ray as my renderer, dropping down under render using and choosing Mental Ray. In indirect lighting, I'll click create for the physical sun and sky. What this does, is to create in the camera, a physical sky shader, with a sun direction linked into it, and also put a simple exposure in. I'll select my perspective camera. And now we can see in the top tabs in the attribute editor, the MIA's exposure symbol and the MIA physical sky.
I'll scroll down. And down in the Mental Ray section, we've got available those shaders. The environment shader is governed by the physical sky, and this will give us a wrap-around sky. The len shader then views that light and allows to see it fairly decently. What we can also see in here is that in that physical sky, we've got parameters for things like multiplier or brightness, conversion, haze, red and blue shift for a non-physical tuning, and even a sun. One of the first things I like to do, is to actually pick that sun, and make it bigger so I can find it, and rotate it over.
The default position is 12 noon on June 21st in San Rafael, California where Autodesk headquarters is. It's almost straight up in the sky and, really, doesn't any of our architecture justice. I'll use my Outliner, choosing Window and Outliner, choosing Show, Objects and Lights to filter down and picking sunDirection. It's a directional light, but really, all the properties are controlled by the physical sky, which in turn is controlling the MIA physical sun, which is mapped into the light shader and photon emitter in the Mental Ray section of that light.
It's suppressing all the MIA shaders. So, if you're thinking you should adjust the sun by going to the intensity and color, don't. Because those are not really working actually. This is just here for direction and everything is controlled by that physical sun. What I'll do, is to scroll up here in the sun, and into the object display section. Under object display I'll make the locator scale about 400, something big and that way I can go and find my sun. We can move it wherever we'd like. It really just depends on where it's rotated.
We can see here, it's very much straight up and we should adjust it so get some more play in our shadows. Now if you've got a designated location or time and you need to adjust the sun accordingly so it's coming from the right direction say, noon in November in Los Angeles or something, you can do that. But if you don't have a specific time, rotate that sun so you've got really good play in the shadows from the most shadow-casting or neatest shadow pieces in your building. I'll hit E for rotate. Pressing and holding E, left clicking and holding and choosing the local rotation on the marking menu, and I'll spin this sun over and aim it down in my scene.
Then I'll rotate it again, diagonally. This way, my sun streams through these entry trellis or beams here, plays into the entry way and under or along the french doors, and casts really great shadows along these concrete walls. I'll have to try out some test renders and see if it works. This will leave me with part of the patio in shade. Which is okay because I'll get a good strong shadow across those umbrellas and the umbrellas themselves will shadow on the furniture. This will also give me great shadows from the trees up against this concrete wall and so this feels like a pretty good sun angle to begin.
Think of it this way, when you are positioning the sun, you as the director of photography are telling the light as an actor how to behave. And the way to think of it is that the light doesn't just happen, it pours in through windows. The lights slinks along floors and climbs up walls. The sunlight caresses curves. We want to think of it in those terms and really direct how does that sun behave as a character in our scene. Once this sun is positioned and rotated, I'm almost ready to do a test render.
But I have one more thing I have to get in place first. On our camera, Mental Ray had added in a MIA exposure simple. I'm going to replace this with a photographic exposure. I'll right-click on the lens shader and choose break connection. And then on that lens shader, clicking on the texture, choosing under Mental Ray lenses, I'll put an MIA exposure photograph again. The default values for this adhere to the sunny 16 rule, where the shutter and F number the inverse of each other. Because I'm shooting outside, I'm going to start off with some default values.
I'd like to run 200, or 400 speed film. I'll reduce that shutter down to a 64th of a second and open up that aperture. Now if you're a photographer you may recognize these values and say, wait a sec, that's so wide open that image is going to blow out. It's okay for a bit because my sky is muted down initially. Once I've got this going, I'll start to soften the shadows and get the direction and quality of the shadows going and then adjust the lighting.
- Creating exterior materials
- Converting paint effects for mental ray
- Positioning the sun with the Daylight system
- Lighting using HDR imagery
- Lighting interior spaces
- Adjusting and optimizing the render settings
- Setting up additional rendering passes for compositing purposes
- Compositing and adding post effects in Nuke and After Effects