From ReMark on Cadtutor:
Some settings that affect 3D output:
DISPSILH – Display Sihouette
This setting affects the results of the Hide command. A setting of 0 displays tessellation lines. A setting of 1 suppresses tessellation lines.
FACETRES – Rendered Object Smoothness
This setting affects both rendering and hide results. The default setting is 0.5. The max setting is 10. A lower setting results in a quicker render time but rounded edges will appear as a series of straight segments. A higher setting results in a longer render time but rounded edges will appear much smoother.
ISOLINES – Contour lines per surface
This setting affects the wireframe view but not the Hide or Render commands. Settings can range from 0 to 2047. The default setting is 4.
SPLINESEGS – Segments in a Polyline Curve
This setting controls the number of segments in a polyline curve. The settings range from 0 to 32767 with the default being 8. The higher the setting the smoother the appearance is of a rendered curve.