Smoothing issue with sculpties from Wings3D

[Miguelito Shilova]

I've had some good success with sculpties created from Wings3D exports, but there is a 'wrinkle' with my sculpty creation - literally - that I'd like to put behind me. I'm using Wings3D 1.4.1 with the Pounceworks plugin.

Starting with a 64 X 63 sphere, I've created this catamaran pontoon. As you can see from the shaded model within Wings3D it is silky smooth ...

However when I bring the UV Map into SL and apply as a sculpty, it develops ripples and wrinkles, particularly on the on the bow ...

I've seen plenty of examples of pontoons out there that look just as good in-world as my shaded model within Wings3D. If anyone knows how to solve this issue, please share. Thanks very much!

Mig

[Chosen Few]

Did you remember to upload the sculpt map losslessy?

[Miguelito Shilova]

I did. I have it on by default. As you can see in the import preview, it shows the wrinkles as well ...

[Drongle McMahon]

Probably the result of the limited resolution of sculpty coordinates. Since there are just 8 bits per channel, positions are represented to an accuracy of only one part in 255 (0..255 is the range of an 8 bit unsigned number). In your 3D program. they probably use at least 32 bits. When they are rounded to the nearest 1/255 of the available range, they move a little, and the result is wrinkles.

The solution is to adjust your vertex positions so that they lie exactly on the grid of available values, while maintaining the smooth shape. Gaia made some detailed instructions for doing this which can be found at the Machinimatrix site (albeit for Blender). You use the grid in your software to move the vertices to exact grid positions while moving them along the accurate surface. You also have to make the shape fit the whole of the 255 x 255 x 255 space if you want to get the greatest accuracy.

Of course, it would be much easier to make the pontoons with proper mesh. That would give you 16 bits of accuracy (1/6536) without any extra work. However, a nice rounded shape like this is probably one of the few cases where the visual quality of a sculpty may be better than that of a mesh with the same land impact of 1. I would still go for the mesh as it is less burden on the gpu.

[Miguelito Shilova]

Thanks for the detailed response. I exported a collada file from Wings3D and played with the mesh importer and was able to get a nice (albeit still slightly wrinkled) model into SL, but with the size I need (10m long) the land impact of one single pontoon was 60. Based on what I've read I should still be able to create a working boat as long as I set the physics of these pontoons to none and keep the count of the linked physical prims under 32 (currently with sculpted hulls, the prim count is 26).

I applied a simple texture grid to my mesh pontoon, and instantly realized I had another issue. Where before the grid laid neatly on the sculpty, now there's considerable distortion of the grid along the long axis - almost a zig zag pattern.

Obviously this will take more time (and patience) to work out. At least I have a much better understanding from this exercise as to how the mesh importer works.

 

[Chosen Few]

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Miguelito Shilova wrote:

with the size I need (10m long) the land impact of one single pontoon was 60.

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For such a simplistic shape, there's no reason the land impact should be so high, at so small a size.  What's the poly count of each of your LOD's?  Chances are most, if not all, of them could be made considerably lower, without diminishing the visual quality of the model. 

This is especially true for the lower levels.  Consider carefully how much detail people really need to be able to see, from distances great enough for the lower levels to be called up.  Just a small handful of polygons aught to be enough.

Also, how complex is the physics mesh?  For a model like that, a simple prism-like or cube-like shape would suffice for physics.  If it's much more complex than that, you're just wasting data.

 

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Miguelito Shilova wrote:

 

I applied a simple texture grid to my mesh pontoon, and instantly realized I had another issue. Where before the grid laid neatly on the sculpty, now there's considerable distortion of the grid along the long axis - almost a zig zag pattern.

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Sounds like you just need to make some simple adjustments the model's UV layout.

[Drongle McMahon]

1. Did you set faces to have smooth shading (I don't know how in 3DM)?

2. Did you replace the vertices correctly if they were moved by the sculpty exporter? (happens in Blender/primstar).

3. The texture oddness is all dependent on UV mapping, which is entirely under your control (but lots of work).

[Miguelito Shilova]

Looks like I may have landed this thing - thanks to everyone's help.

I corrected the UV map in Wings3D, and in so doing it also seems to have helped with the wrinkles, as well as allowed me to get the poly count down considerably (as Chosen suggested). Land impact on a single pontoon is now 9 as opposed to 60 - and it looks MUCH better.

I also wrapped the texture grid to it and the zig-zags are gone as well - I'm definitely moving forward with this model!

Thanks again everyone!
Mig

[Chosen Few]

Nice job, Mig.  I'm glad to see you're moving forward so positively.

I hope others will also learn from this thread, as your model is a great example of "less is more".  Higher poly counts don't always mean better looks.  Sometimes, simplicity is king.