Autodesk 12812-051462-9011 User Guide 3 - Page 927

unit that 3ds Max uses for its calculations. The Display Unit is just a tool that lets you customize how units are displayed in the user interface. The following two scenarios show how to set unit scales after importing geometry that has been created using different units than what is currently set in 3ds Max: Example 1: You import a table that was created in AutoCAD using metric scale. The table is 9 units long, which corresponds to an actual length of 90 centimeters. When the table is imported into 3ds Max, it will measure 9 scene units. Therefore, in the Units Setup dialog, you must set Scene Unit Scale to 1 Unit=10 centimeters. Your table is now the correct units because it is 90 centimeters long in 3ds Max model. Example 2: You have an AutoCAD model that was created using Architectural Units. The model is a room measuring 20'-4" long. In AutoCAD, Architectural Units are stored as inches. Therefore, before importing the model to 3ds Max, make sure to set the Scene Unit Scale to 1 Unit=1 inch. Once imported to 3ds Max, the room will measure 244 units long (20'*12+4"). TIP Use the Measure Distance tool on page 2613 to quickly check dimensions in 3ds Max. Physically Based Workflow Use radiosity on page 6168 to create physically based lighting simulations. When doing so, keep in mind the following: ■ Scene dimensions: Make sure your scenes are accurately dimensioned, with consistent units (a light bulb in a room 120 meters high would look a lot different than it would in a room 120 inches high). ■ Lights: You should work exclusively with Photometric lights on page 5005. You should also make sure that the light intensities are within a normal range. ■ Natural Lighting: To simulate natural light, you should only use IES sun on page 5154 and IES Sky on page 5157. These provide accurate photometric representations of sunlight and skylight based on a specified location, date and time. ■ Material Reflectance: You should ensure that the materials you use in your scene have a reflectance value on page 5324 within the range of the physical materials they represent. For example, a painted white wall should have a maximum reflectance of approximately 80%; however, a pure white color 6182 | Chapter 20 Rendering