Seams in sculpties

[Madeliefste Oh]

I came across this problem a few times now.When I make sculpts that are more or less rectangle orientated I use a cylinder or a plane to start with, and then fold it as long till I get the shape I want.I do this to avoid the ugle point where all comes toghether and that is so hard to texture nicely.

In my 3d prog the sculpt looks fine, and is closed at all sides. But then when I upload it to SL and I use a cylinder or a plane as stichting type, I get a little hole at one point of the sculpt. 

When I use the stichting type 'sphere' for the sculpt the hole closes, but then the texturing is not ok anymore. 'The ugly point where all comes together' appears again. It is exactly at this point that I'm not able to close the sculpt completely.

Has any body else come across this problem? Is there a solution for it?

[Chelsea Malibu]

I too have had this problem but don't know the answer so I am hoping someone can respond to this as well. I use 3DS and have been able to reduce some of it by smoothing those poly's along that edge but it only helps and does not eliminate.

[Drongle McMahon]

It looks like you sculpty map maker is not making the stitched pixels quite identical. You may be able to repair that by editing the bitmap. First, I hope you are using a standard map size (64x64, 32x 128m etc.... If you are using a bigger one, that may be the problem). Then the stitched vertices are specified by the first and last pixels in either direction. All you have to do to ensure precise stitching is to copy the leftmost pixel column (and/or bottom row) and paste it into the rightmost column (and/or top row). Note that the last column/row is only used for the unstitched edges. These are the top for cylinder and both top and right for plane. In the stitched topologies, this is done automatically when the gometry is generated in the viewer. Make sure you never save a map with a lossy file type, like jpg. I always use tga, but bmp or png should work too, I think. 

 

[Madeliefste Oh]

Hi Drongle, thanks for replying.

Sure I use a standard map, in this case it's 64x64. The file is saved as a 32bit tga file, before uploading to SL. For sculpts I mainly work in Blender and use the Domino Marama scripts to export.

So do I understand you right, I must use the colored sculpty map tga and replace and copy paste the left row to the right row, just in Photoshop or such a program?

[Madeliefste Oh]

Wow yes, that is what you mean. I just had to replace one pixel... and now the sculpt is perfectly closed.

1000 kudo's Drongle. You know so much and you are always willing to share your knowledge. I really appreciate your contributions.

[Drongle McMahon]

I'm glad it worked. :matte-motes-smile:

With any luck, Gaia will be along to tell you how to avoid it in the first place. That will be a better solution.

[hibit Spad]

Actually 64x64 is not standard.

 

32x32 is the largest you can go.

 

1024 faces is the max you are allowed.

 

So in the process of shrinking thinngs to fit you are getting rounding errors more then likely.

 

Check out the SL wiki on sculpts for more info.

 

 

 

 

[Drongle McMahon]

Considering only square maps for simplicity...

32x32 is indeed the standard (maximum) number of quad faces in the sculpt mesh. In the case of the unstitched plane, that requires 33x33 vertices, with the consequence that 32x32 is not enough pixels to specify them. Since the upload system only accepts power-of-two pixel dimensions, it has to be 64x64 to accomodate the extra vertex row/column. That is why a 64x64 map is the standard. The vertex data is taken from all the even numbered pixels (starting at 0), to give 32, and the last pixel (63) to give the 33rd. All the other pixels are ignored. In the case of stitched dimensions, pixel 63 is copied from pixel 0 at the of the same row/column, so that the first and last vertices coincide, and the map's pixel 63 is ignored.

In the original sculpty implementation, larger or smaller maps, such as 32x32, were interpolated to give a 64x64 map. So a 32x32 map would work and give a 32x32 face mesh. However, since the introduction of oblong maps etc., these smaller maps now specify a sculpty with fewer mesh faces. Thus a 32x32 map now specifies a mesh with 16x16 faces (17x17 vertices unstitched).  The same extra-pixel mechanism is used for unstitched versions.

Maps larger than 64x64 are simply subsampled at the relevant pixels. They were once widely used to reduce distortions resulting from lossy compression. Since the advent of lossless compression, they are just wasteful of texture bandwidth.