Sculpt problems

[Kolby Nissondorf]

Hi everyone 8-)

Ive been having problem with my sculpt letters..

Could someone please help me? They come out all screwed up looking unless your within 5 meters of them

[bee Baroque]

try upping your LOD factor a bit. i have mine at 6, but i think it should suffice having at at 3 or 4.

also make sure they are the right stitching type. depending on how the sculpt is made they might need different stitching type.

[Drongle McMahon]

This is the result of something called LOD (Level-of-detail) switching. Assuming you used the standard 64x64 pixel sculpt map (it's similar with other sizes, but there can be unexpected details), the pixels used to make the vertices when you are close to the object are (index 0..63) [0,2,4,6,.....,58,60,62,63] in each dimension, for a planar stitching type. If it's a stitched dimension, pixel 63 is replaced by pixel 0 to achieve the stitching.

A mechanism, called LOD switching is used to reduce the workload of the graphics card. As the camera moves away from an object, when it's distance from the object reaches certain multiples of the object radius, the number of vertices in the  object are reduced. The assumption is that as the object fills a smaller area of the field of view, less detail is needed for acceptable appearance. This was well suited to the original rounded objects scuplties were invented for, but lead to problems with sharp edges.

You can see the LOD switches happening with a cylinder as the number of edges around it's circumference is reduced. For sculpties, the reduction in vertices is about 1/4 with each step. This is achieved by skipping alternate vertices, equivalent to pixels in the map, so that after the first step, only pixels [0,4,8,....,56,60,63] are used, then [0,8,16,...,48,56,63], then [0,16,...,48,63].

The effect of this on you sculpty depends on which pixels are used to specify the visually important vertices. To stop the sort of distortion you see in you letters, you need to make sure that all the edges are specified by pixels that are still there after at least the first LOD step.Someone will be along to point you to at least one tutorial about how to do that (hint: if you are using Primstar, model at as manyn levels og subdivision or multires as you want to survive LOD switches).

The distances wherev the LOD steps happen depend on the radius of the prim, which is the length of the diagonal from the center to a corner of the bounding box, and the setting of a debug variable called renderVolumeLODFactor (accessible through the Adbanced menu). If renderVolumeLODfactor is the default 1.25, the first switch is at about 5 times the radius. The remaining two switches are at four and eight times that distance. The value of renderVolumeLODFactor simply multiplies these distances. Setting it to a high value will postpone the distorting effects to a greater distance, at the price of puitting much increased strain on your graphics hardware (reducing fps). Since you cannot assume that all the people you want to see your letters will be using other than a default setting, it is better to makle sculpties that will do what you want for the default setting.

.... and bee is right, it does look as if you may have a stitching problem there too.

 

[Josh Susanto]

For a letter display like that, I might also suggest using alpha sculpted letters that are simple transparent relief planes with the raised portion (the letter part) painted in.  You just won't see them from the back unless you do mirrored concavity (easy, believe me).

I'm not absolutely sure why plane reliefs seem to present fewer obvious LOD problems, but it seems to me that they do.

If you have any problems making such a letter, I can either make a few for you or show you how.