When you open drawings created with earlier versions of AutoCAD, content is converted to be usable in rendering.
Lights, Materials, and Cameras
Lights, materials, and cameras have been improved but some older drawings may contain AutoShade information, such as lights, scene blocks, and camera blocks.
Lights and materials used in older drawings can be converted. AutoCAD 2008 introduces the 3DCONVERSIONMODE system variable. With the system variable set to the default value of 1, AutoCAD 2008 will automatically convert lighting and materials for older drawings. Additional information on converting drawings can be found under the topics Converting Lights and Converting Materials.
