The smoothness of 3D DWF models was improved in AutoCAD 2006 using the FACETRES variable.
For AutoCAD 2007, the smoothness of 3D DWF models is improved by changing the value of the 3D DWF Precision (3DDWFPREC) system variable. The setting for 3DDWFPREC ranges from 1 to 6. Unlike FACETRES, 3DDWFPREC is specified as an integer. Values like 5.5 are not allowed. Higher settings greatly improve the appearance of objects in the Autodesk DWF Viewer. The default value is 2.
3DDWFPREC is a global setting that affects all objects in the 3D model. Therefore, higher values have the potential of resulting in very large 3D DWF file sizes.
Setting the value as high as 4 has a modest effect on increasing the smoothness of the surfaces in the resulting DWF file with little increase in DWF file size. Setting a value of 5 has a noticeable visual impact with a moderate impact on DWF file size. Cranking up 3DDWFPREC to 6 yields the smoothest surfaces, but the resulting DWF file is indeed larger.