Analytical surfaces are planar, cylindrical and conical, while nurbs surfaces don't confirm that geometry. You'd choose analytical surfaces to derive planar, axial, diametric/radial and maybe conic features, the features that you work off for mechanical design. Sketchup models lose reference to curved-surface features like that when they're imported into VC. The Nurb surfaces that PPPro creates are suitable for making free form or amorphous shapes (subdivision models or scanned real-world objects) that aren't composed of analytic surfaces, or those that have nurb surfaces over analytic shapes, say a freeform face on a cube, for spacial registration, workable in CAD. That simplifies scaling over a larger range, makes it easier to shell such shapes for mold design or similar, gives smaller file sizes than a high-resolution mesh in many cases, and makes it easier to specify faceting resolution for more sophisticated rendering or conversion to rapid prototyping .stl format.

Edited by user Wednesday, November 30, 2016 6:51:47 PM(UTC)  | Reason: afterthoughts

FYI, today i updated the SketchUp importer to support SketchUP 2017. This will be in the next build.

Tim

Edited by user Thursday, December 1, 2016 4:41:24 PM(UTC)  | Reason: Not specified