This page contains tips on building good areas, specifically as regards lighting.
When creating an area, there are many tools for lighting it. But the very first thing to do is to get the basic lighting correct. Each environment setting allows the specification of Ambient, Diffuse, and Directional light angles. It's important to understand each of these parts.
The direction of a light source is controlled by the Azimuth and Polar angles. Azimuth is the angle of the light around the area. Think of it as the direction on the compass the light is coming from.
Polar angle is the direction the light is coming up or down on an area. For an outdoors area, it is always coming down... from the sun. So a polar angle of 145 would be the sun at about halfway up the sky. A polar angle of 180 would be the sun directly overhead.
Note: Make sure you don't have the polar angle having light coming directly across or up, except in very unusual situations.
Adding a light
Via the Create menu choose Light.
For outdoor areas, the directional light is typically the sun. Inside, it's more vague about what this light source is.
Diffuse is the color and intensity of the light source. Anything the light touches (because it faces it) will be lit by this color.
Ambient is how bright things are that are not being touched by the directional light. In other words, it is how light or dark the shadow regions of areas are.
Ambient must always be DARKER than Diffuse. For a sun-drenched outdoors area, Diffuse would be bright white and Ambient would be some dark grey. Having a bright ambient and a dark diffuse would be a problem!
Ambient lets the Area Designer give some visibility to things in shadow... because light bounces all around, this is a crude approximation of the global illumination of an area. To give things three-dimensional shape, it is necessary to have a good contrast between the ambient and diffuse.
Lighting and the Skydome
For outdoor areas, try and match the lighting to the skydome. Look for where the sun appears in the skydome and match it with the Azimuth and Polar Angle. Or rotate the skydome to match the desired lighting, by moving the appropriate slide on the Spec panel.
HDR ( High Dynamic Range rendering)
Enabling HDR allows for a greater range of light to be rendered. In general this means when a scene is lit things can be very dark or very light and show off a broad range in between those extremes. With out HDR on those values would be clamped to a smaller range. The most commonly seen result of this is that objects will have a bloom effect when hit by very intense light sources.