Hi Steve,

> Hmmm, Since I'm working in mm, the gap between surface
> and the profile is .02mm at largest point, so I guessing to
> the naked eye it will look smooth.?

It probably would be hard to notice it - but the gap there is just a gap between the on-screen "realtime" display mesh and the edge curve, it's not a gap in the actual surface itself.

When you go to export to a mesh format like STL or whatever, you will be able to adjust the export options to generate a denser mesh at that time if you want, and if you made it denser than that display mesh you would see that area actually get filled in with polygons to make it smoother than that.

You end up seeing a gap in this case in the on-screen display because curves get displayed by the display engine to a high degree of accuracy - they're continuously refined until the on-screen display is within a screen pixel of the true curve geometry.

But unfortunately it would take too long to do that equivalent "1 pixel display accuracy" type thing with surfaces, so surfaces get a somewhat rougher display mesh calculated for them just one time and then that display mesh is used for all display of it after that, it's not recalculated when you zoom in closely unlike the curve display.

So anyway, that's why you may see some disagreement between the shaded surface display and the display of an edge curve - the edge curve display is much closer to the actual model geometry while the surface display is kind of rougher in order to keep things fast.

That rougher surface display does not mean that your actual surface itself is rough though, it's just that current on-screen display that looks like that, when you go to export you can generate a denser mesh at that time if you want to.

- Michael