2012

Table Of Contents
Standard and Photometric Lighting Work-
flow
Types of lighting selected globally affect a drawing.
Set the Type of Lighting
AutoCAD for Mac offers three choices for lighting units: standard (generic),
International (SI), and American. The standard (generic) lighting workflow is
equivalent to the lighting workflow in AutoCAD for Mac prior to AutoCAD
2008. The default lighting workflow for drawings created in AutoCAD 2008
and later is a photometric workflow based on International (SI) lighting units.
This choice results in physically correct lighting. The American lighting unit
provides another option. American differs from International in that
illuminance values are formatted in foot-candles rather than lux.
In previous versions of AutoCAD for Mac, standard lighting was the default.
You can change the type of lighting with the LIGHTINGUNITS system variable.
The LIGHTINGUNITS system variable set to 0 represents standard (generic)
lighting; set to 1 represents photometric lighting in American units; set to 2
represents photometric lighting in International SI units.
Photometric Lights
Photometric lights are physically correct lights. Physically correct lights
attenuate as the square of the distance.
Photometric properties can be added to both artificial lights and natural lights.
Natural lights are the sun and the sky. The natural lighting is represented
interactively by a viewport background type.
You can create lights with various distribution and color characteristics, or
import specific photometric files available from lighting manufacturers.
Photometric lights always attenuate using an inverse-square falloff, and rely
on your scene to use realistic units.
Illuminate a Scene
You can add point lights, spotlights, and distant lights and set the location
and photometric properties of each.
780 | Chapter 13 Render Drawings