Disappearing Sculpty Top

i have created a vase sculpty using rokuro and uploaded it to sl and it works fine except:- when i move the camera back away from it the top disappears, move in again and it reappears. Is it my system or is it SL?

With any prim in SL, as you move the camera farther away, you see a progressively less detailed rendering of it. This is done by rendering the prim using fewer and fewer vertices. This is referred to as LOD handling.

With traditional prims, the prim shape is known, and the code is carefully written to chose the best vertices to drop to retain as much of the shape as possible. But with a sculpty, the code doesn't understand anything about the shape being made by the sculpty, and so it drops points using a general rule based only on the position of the pixel in the sculpty bitmap.

In your case, the top rim of your vase is being represented by vertices that are getting dropped as the LOD is reduced. The usual remedy for this would be for you to double (or more) vertices in Rokuro at the rim so that the rim is still represented as vertices get dropped. A more sophisticated method is to actually understand which vertices are going to be used at each LOD, and design your sculpty with that in mind.

Thanks for that Omei, I learn something new every day in SL. Would it have any effect using different base prims, cube, cylinder etc?

Not really. The shape you start from doesn't have any effect on which points are used to render lower LOD.

This is something that sculpty tool makers can help with -- either identifying which vertices are going to be used at different LOD, or building in previews at various LOD.