Accurate Sculpting

Is there any way to increase the accuracy of sculpty prims?
I've done quite a bit with them but while in sl they hold maybe 25 to 50% of the detail I had in Maya and Blender.
I need sharp edges that stay so texturing can be precisely uv mapped to them. However sculpty prims change shape depending on the client settings and distance of course.
So are we not able to make anything other than claymation with these?

The claymation look is great and everything but I'd like to know if I missed something.
Thanks.

The main method I use in Blender is to start with a 4 vertice uncapped cylinder. I multi sub divide the 4 vertical edges by 3, and mark one of them as a seam then unwrap. This gives a 4 x 4 face uv map. I then use Multires and add layers of Catmull Clark or Simple Subdivision depending on whether I want curves or flat. You can add 4 layers of Multires to the base cylinder to get the full 32 x 32 face map. You can switch between the layers and work on each LOD seperately. The different layers in multires correspond exactly to the LOD in SL this way, making it easy to control what the model will look like at all distances. Just remember the pole loops will need closing to a point, I usually do this at a high level then check and tweak the lower LODs.

4/6/2007 added the following.. bad form editing a post like this, but seemed most appropriate place to put it

Here's the blend file I use as a starting point for new sculpties using this method. When closing the poles, scale to 0.1 or 0.2 and not 0.0 - you'll see black spots on the edges of the sculptie map if you go too small on this. Also watch out for it losing the UV map, multires is new in Blender and still has a problem or two lurking. Going to object mode before baking seems to avoid this. If you see the UV map go, then undo will generally get it back.

After I'm happy with the modelling, I save as two seperate blend files. The second is for texturing. I add a few extra multires layers before baking any textures. You'll get finer detail in ambient occlusion maps etc by doing this.

Please shut up any further in the builders forum and go to
https://wiki.secondlife.com/wiki/Talk:Sculpted_Prims
to talk about your bloody sculpies

Yeah that page is useless and utterly ugly to try to read, no thanks , this will be the place till they manage to *gasp* open a new place to talk about it, deal with it : p

They're not going to add another forum for scupts, which is only logical, since it isn't even SL software people are talking about.
And that page may look ugly, at least half the questions that've been asked here a hundred times are already answered THERE!

There's been a lot of discussion about this, but it is spread out over the many threads covering the various exporters and the Wiki. Maybe this thread will serve as a better focus for the discussion.

The details of the modeling process are going to depend on the tools you use. But eventually, everything boils down to understanding what goes into the sculpty bitmap and how SL interprets that bitmap.

Here's a simplified summary of what I have gotten from the discussion. I'm going to ignore the idiosyncratic treatment at the poles, and make the simplifying assumption that you are going to use a square mesh with dimensions a power of 2 (16x16, 32x32, 64x64, ...).

1) You need explicit control over the mesh of vertices that determine the values in the sculpty map. If your chosen modeling method doesn't expose that mesh until late in the modeling process, it's going to be very difficult to manage LOD.

2) You need to be aware of which mesh vertices are going to be used at various LOD. At the highest LOD, That's a 32x32 mesh. (For those in the know, remember that I am ignoring the special treatment at one of the poles.) At the next highest level, all the points with an odd column or row index are dropped, leaving a 16x16 mesh. This smaller mesh is going to determine what the sculpty looks like at the second LOD, so you need to keep those mesh points in mind if you want to manage the shape degradation at the second LOD. For even lower LOD, the same process of dropping every other row and column is used to reduce the mesh to 8x8 and then 4x4.

3) Create an overly large sculpt map to reduce compression artifacts. This is a hack that won't be necessary when (if?) we get lossless compression of small textures. But for now, if accuracy is important enough to be worth a small increase in rez speed, open your sculpty bitmap of 64x64 or smaller into a paint program and resize it to 128x128, _without_ interpolation. See
/8/20/183764/12.html#post1533245
for an example of what this can do, and why I suggest 128x128 over a larger size.

No thank you, I'm quite happy discussing this new form of building here.

Geez, Marcush, give it a rest. The purpose of this forum is to hold discussions. The wiki has a lot of good information on it, but by its nature, it's not suitable for conversation. That's why forums exist.

As you pointed out, it's unlikely that they'll add another forum for sculpties, not should they. Sculpties are just one more building tool, recently added to the same palette of tools we already had. They absolutely fall under the heading of Building, so discussing them here is the right thing to do.

Look, it's no different than any other time new building tools have been added to the system. When the ring prim was added, for example, there were lots of discussions about its capabilities, and how to use it. Same with other changes that have happened over the years, such as tapers, revolutions, radius deltas, twists, etc. Those discussions happened right here where they belonged. No one ever went around throwing a fit, and saying "I'm so sick of hearing about rings. Everyone shut up. Me, me, me, me, me, me..." as you seem to be doing here regarding sculpties.

As I said to you in that other thread, I'm sorry if sculpties are beyond your grasp. That doesn't mean everyone else should be stifled or barred from discussing them. Nor everyone is capable of learning just from a pre-compiled bank of information. Some people's brains are wired so that they best learn by discussing, which is why these forums exist. Ever wonder, for example, why 90% of the Photoshop questions on the texturing forum can easily be answered just by reading the help file? That's why. Not everyone learns well from that kind of resource. You don't see too many people saying "shut up and read the manual" though, the way you're saying "shut up and read the wiki" or even "shut up and post on the wiki".

If you don't like this forum or its purpose, I cordially invite you not to read it. Good luck.




Omei had some good things to say on this subject. I'll only add that you'd be surprised what a good texture bake can do, even in spite of the relative unpredictability of the LOD system. We should definitely get a dedicated thread going on that subject some time soon. I'd write more about it here, but unfortunately I'm hitting the edge of my forum time budget for the day, and it's a big subject.

Blakar Ogre has discovered the real reason 128x128 sculpt maps are necessary for accuracy -- the compression quality on smaller images is actually significantly worse than on 128x128. He has filed a bug report at https://jira.secondlife.com/browse/MISC-259. I encourage sculpty builders to vote to have it fixed.

Update: The Lindens closed MISC-258 because it essentially duplicated MISC-866. If you voted for MISC-258 before, that vote has been lost. You need to vote again at https://jira.secondlife.com/browse/VWR-866.

In the meantime, if accuracy is important for your sculpty, it looks like you are pretty much forced to use at least a 128x128 bitmap.

Interesting information and voted...

the login doesn't stop loading

Great info. Thanks everyone.
The 128 size is what I've been using. I think my expectations were probably just too high for what I was hoping for.
I was also trying to sculpt an entire ship hull with one prim and that just doesn't seem feasable in sl yet.
Unless it's supposed to be some kind of organic based ship that randomly morphs into dog poo.

They seem to do ok for small parts though.


I have one other question though. What do most people have their object detail set to?
I thought it was somewhere in the middle. I'm guessing most don't have it any higher than that?
I just hate making things only to find out maybe 5% of the SL population can see it correctly.

So in Photoshop, resize without interpolation would be "nearest neighbor"? It won't resize without choosing a resample method and the choices are nearest neighbor, bilinear and bicubic.

I don't know Photoshop, but I think the answer is probably yes, use "nearest neighbor". What you want is that the resized bitmap is composed of square blocks, where all the pixels in one block are the same color.

What a moron

First: I may have put some rough names for the bloody sculpties, but I certainly didn't resort to calling YOU names.
Second: It's basically a rewording of something said by Torley Linden, which still has the exact same logical meaning which he gave, just worded a bit more pressing.

And no, I don't hate sculpties, they are a great addition to SL, saving many prims for many now happy people. But they belong as much in the Builders forum as they would in the Animations forum: they don't belong in either.

I would like to request that people not discuss the merits of Marcush's proposals in this thread, since it is clearly off-topic.

I'm personally having trouble with the compression with chamfered edges and flat areas where the edges are more spread out. I find that my sculpts with a lot of vertex density come out pretty smooth, but when I work on something like a cube with chamfered edges on the corners and hard beveled edges on top/bottom, not so good.

I too have gotten excellent accuracy with the texture baking method, finishing up a tutorial on doing this in Carrara 5 Pro. But all fail when it comes to the compression artifacts. They look great in the sculpted prim preview though.

Also, I've found that edges will hold their shape better on LOD if you have more edges/vertices devoted to them. But there's limits to what one sculpt can do.

Yes! That is the secret to at least 'sharper' edges Hyp (texture compression artifacts not withstanding) Where I want sharp edges I have taken to 'doubling up' the vertices there.

LODs will I think always cause a problem .... that I'm not sure can be easily overcome.

It is my understanding they are more designed for 'organic shapes' as opposed to low prim 'clock mechanisms'.

gryff

Pardon him, I suspect he is a disgruntled librarian.

here is what I have been doing as a standard;

as others have said I cannot stress more!!! Make sure you have enough vertices in the area where you need the detail in the mesh model. Use two sculpties if you can't bend the shape you are looking for out of one. The starting shape is your limitation, doing a concave sculpt of a sphere will break down the LOD, you need to move vertices around to cover the problem area.

Sculptie textures are baked to higher pixels (at least 256px) square in 3d app.

open in photoshop filp if needed resize to 64px.

I have found that some of the 3d programs when you bake at 64 px image the result is pixelated.

What I look for is a smooth almost shiny looking sculpt map.. when I see that it means the sculpties is probably good.

I have tried upload larger sculpt maps up tp 1024 but have not seen any significant difference in the LOD, and your sculpties will look like blobs as they take longer to load the shape.

-Why

need a hug?

The concept of LOD in combination with sculptures is rather broken. The interpolation knocks out any chance of getting good results unless you use big textures which is a memory hog.

The good news is that it's patchable. As soon as LL fixes compression for 64x64 I'll work on some proposals of how to change the way LOD affects the textures. I've got at least 2 possibilities but I can't propose either for now as the results can not be interpreted correctly as long as small textures show severe distortion due to compression.

It's not that bad. Using the methods I described above (since updated with my new-sculptie.blend for download) I get reasonable results like the ones shown here:

/53/fd/182727/6.html#post1535277

Those are sculpties baked in Blender at 64 x 64 and just uploaded. On the main picture, front row is full detail, 2nd row is 2nd level of detail. The smaller image shows the sculpties from further away, front row is 2nd LOD again, back row is 3rd LOD and the inset picture shows smallest LOD, it's not until you hit this that things like the cross on the king is lost.

Needs a bit of care and attention during modelling, but it isn't hopeless. As you can see from the multires LOD in blender below, what I get in SL is pretty much identical to what I see when modelling.

It depends on what you expect. You are apparently willing to accept that you won't have sharp edges. Hence the difference between interpolation and subsampling is low. But for those who do want to have sharp edges it's a lot better if LOD is based on subsampling as this can be taken into account during design while taking into account interpolation is madness.

I also don't really get the explanation on the LOD's in your pictures. You indicate 4 levels but as far as I know there are only 3. Max detail is a 33x33 mesh (that's including stitching and 2 rows containing just poles), next is 17x17 and then 9x9. My testclient has added code to output info on sculpt rendering and I've never seen 5x5 being used and if I'm not mistaken that would be beyond how low it goes anyway. I'll check tonight.