Second Life Forums Archive - Accurate Sculpting

Omei Turnbull

Registered User

Join date: 19 Jun 2005

Posts: 577

06-04-2007 08:22

From: Blakar Ogre

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 agree, Blakar. I've been trying to think of a situation where interpolation would be better than subsampling for managing LOD, and I haven't come up with an example.

Omei Turnbull

Registered User

Join date: 19 Jun 2005

Posts: 577

06-04-2007 08:26

From: Blakar Ogre

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.

With the medium setting for object mesh detail (which is the default, at least on my machine) I see 4 distinct LOD. Perhaps your preferences have a higher setting, causing you to never see the 4th level?

Domino Marama

Domino Designs

Join date: 22 Sep 2006

Posts: 1,126

06-04-2007 08:37

From: Blakar Ogre

You indicate 4 levels but as far as I know there are only 3.

I'm sure I saw that level as some point, maybe was on early version of sculpties on test grid. When the entire sculptie is only a few pixels wide on screen, it's hard to tell exactly which LOD is being used. Glad someone has a better way than eyeballing it to tell

It's still handy to have that level as the starting point during modelling, it is as easy to make a cube based model as a cylinder one from it.

We already know that the compression is to be turned off for sculpties so I'm not worrying about minor artifacts caused by that at this point. If there are still problems after wednesday then I'll join the calls to fix it

If I want really straight edges I tend to double up (or more) on vertices for better shading, which helps mitigate the interpolation issues as well.

All I'm trying to point out here is how methods such as multires give a far better idea of how the LOD will look than modelling just with the highest level mesh and hoping for the best.

Blakar Ogre

Registered User

Join date: 18 Mar 2006

Posts: 209

06-05-2007 01:07

I did some tests and even with mesh detail at its lowest settings I'm not going below 9x9. With lowest detail it simply never goes above 17x17 and hence you have only 2 levels. What might be happening though is that the sculpt texture interpolation does have more steps so that might be causing the impression of more LOD levels. I'll have to see if I can track this with extra logging.

Kornscope Komachi

Transitional human

Join date: 30 Aug 2006

Posts: 1,041

06-05-2007 06:05

Thanks for that info and file Domino.
I now know why those black bits turn up in the map and what that multires button does!
I've spent a lot of time with my head in Blender this past two weeks and I still haven't got anything decent to show for it yet. But, I keep at it..

_____________________

SCOPE Homes, Bangu
-----------------------------------------------------------------

TomHa Zymurgy

Registered User

Join date: 15 May 2007

Posts: 7

I can see sculties everywhere

06-05-2007 11:07

Hi there!

May i share my desperate trying to be sharp end detailled with my sculpted prim.
i made a little template texture that i use in blender to (manualy almost) place my uv grid.
It s a simple 64 64 pixels map with 2 pix checker so i can snap the vertices to pixel straight at center of the "32 32" sculpted vertices. With later resamplin in gimp without interpolation to 256 256 (yes i m bad with linden data load...) i get "nice" results but not perfect =[. Should it be that simple? NO sure not...

Now the weird:
-if i bake on 64 64 iget better results, and vertices are not at the same place. Are there 32 32 vertices?
-when you look at the in world wireframe at the "seam" (where the shape is closed wrappin the first and last column of uv) it looks like they (sl) creat another row of faces that cover the last other one.Looking at coulor texture confirm this impression.What data is used to create this 33 column of vertices/faces?
-i thaught after readind (yes i did

) the "sculted talk" thing that the pole were created by "averaging" (misterious way....) but my poles appear always stuck on the border of laste "circle" of vertices.The average vert of merged vert is?

What i m really not sure about and gave me "various" results:
-33 33 vert! What? how much? why the hell didnt they mention!
-Poles seam to be taken on the midlle pixel of first and last row.That s an average....
-Stil experimenting for the last 33th column... and texture that wrap ok.... Still exited by sculpted prims! =)

Blakar Ogre

Registered User

Join date: 18 Mar 2006

Posts: 209

06-05-2007 11:52

Faces: there are 32 faces. The seam is a face connecting the first and last columns of pixels
Poles: The poles are the pixels on width/2 at top and bottom. As it counts from 0 that means the 33th pixel in a 64x64.

To really have all the info please read http://wiki.secondlife.com/wiki/Sculpted_Prims:_Technical_Explanation

Strife Onizuka

Moonchild

Join date: 3 Mar 2004

Posts: 5,887

06-05-2007 15:06

Just a friendly reminder that this is the correct forum for discussion of sculpted prims and things are much nicer when everyone is civil.

_____________________

Truth is a river that is always splitting up into arms that reunite. Islanded between the arms, the inhabitants argue for a lifetime as to which is the main river.
- Cyril Connolly

Without the political will to find common ground, the continual friction of tactic and counter tactic, only creates suspicion and hatred and vengeance, and perpetuates the cycle of violence.
- James Nachtwey

Magicrat Voom

Registered User

Join date: 4 Jun 2007

Posts: 1

Problems with texture on sculptie

06-07-2007 07:45

Hey

I created a head like sculptie using Wings3D and the exporter and uploaded it to SL - no problems.

I then created the texture map by exporting as .obj and using UVMapper to create it (using z-alignment and x-offset of 0.5). Painted it with Photoshop and used 3D Canvas to preview it.
Everything looks great and properly aligned.

The problem I have is that when the texture is then uploaded to SL and applied it is stretched and so not aligned?? I had to change the rotation, etc of the texture but that's not a problem.

Do you have to use x or y-alignment when creating the texture map in UVMapper instead if the z-alignment I used?? Or am I missing something more fundamental.

Thanks for any help.

bebop Kohime

Registered User

Join date: 16 Mar 2007

Posts: 2

scaling before upload sculpie textures

06-07-2007 11:15

From: Omei Turnbull

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.

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#post1533245/8/20/183764/12.html#post1533245
for an example of what this can do, and why I suggest 128x128 over a larger size.

OMG what a difference puting the bitmap into photoshop and changing it to 128x128 tga before upload made very large amounts of detail was restored thanks very much for this tip

cheers

Accurate Sculpting
Omei Turnbull Registered User Join date: 19 Jun 2005 Posts: 577	06-04-2007 08:22 From: Blakar Ogre 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 agree, Blakar. I've been trying to think of a situation where interpolation would be better than subsampling for managing LOD, and I haven't come up with an example.
Omei Turnbull Registered User Join date: 19 Jun 2005 Posts: 577	06-04-2007 08:26 From: Blakar Ogre 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. With the medium setting for object mesh detail (which is the default, at least on my machine) I see 4 distinct LOD. Perhaps your preferences have a higher setting, causing you to never see the 4th level?
Domino Marama Domino Designs Join date: 22 Sep 2006 Posts: 1,126	06-04-2007 08:37 From: Blakar Ogre You indicate 4 levels but as far as I know there are only 3. I'm sure I saw that level as some point, maybe was on early version of sculpties on test grid. When the entire sculptie is only a few pixels wide on screen, it's hard to tell exactly which LOD is being used. Glad someone has a better way than eyeballing it to tell It's still handy to have that level as the starting point during modelling, it is as easy to make a cube based model as a cylinder one from it. We already know that the compression is to be turned off for sculpties so I'm not worrying about minor artifacts caused by that at this point. If there are still problems after wednesday then I'll join the calls to fix it If I want really straight edges I tend to double up (or more) on vertices for better shading, which helps mitigate the interpolation issues as well. All I'm trying to point out here is how methods such as multires give a far better idea of how the LOD will look than modelling just with the highest level mesh and hoping for the best.
Blakar Ogre Registered User Join date: 18 Mar 2006 Posts: 209	06-05-2007 01:07 I did some tests and even with mesh detail at its lowest settings I'm not going below 9x9. With lowest detail it simply never goes above 17x17 and hence you have only 2 levels. What might be happening though is that the sculpt texture interpolation does have more steps so that might be causing the impression of more LOD levels. I'll have to see if I can track this with extra logging.
Kornscope Komachi Transitional human Join date: 30 Aug 2006 Posts: 1,041	06-05-2007 06:05 Thanks for that info and file Domino. I now know why those black bits turn up in the map and what that multires button does! I've spent a lot of time with my head in Blender this past two weeks and I still haven't got anything decent to show for it yet. But, I keep at it.. _____________________ SCOPE Homes, Bangu -----------------------------------------------------------------
TomHa Zymurgy Registered User Join date: 15 May 2007 Posts: 7	I can see sculties everywhere 06-05-2007 11:07 Hi there! May i share my desperate trying to be sharp end detailled with my sculpted prim. i made a little template texture that i use in blender to (manualy almost) place my uv grid. It s a simple 64 64 pixels map with 2 pix checker so i can snap the vertices to pixel straight at center of the "32 32" sculpted vertices. With later resamplin in gimp without interpolation to 256 256 (yes i m bad with linden data load...) i get "nice" results but not perfect =[. Should it be that simple? NO sure not... Now the weird: -if i bake on 64 64 iget better results, and vertices are not at the same place. Are there 32 32 vertices? -when you look at the in world wireframe at the "seam" (where the shape is closed wrappin the first and last column of uv) it looks like they (sl) creat another row of faces that cover the last other one.Looking at coulor texture confirm this impression.What data is used to create this 33 column of vertices/faces? -i thaught after readind (yes i did ) the "sculted talk" thing that the pole were created by "averaging" (misterious way....) but my poles appear always stuck on the border of laste "circle" of vertices.The average vert of merged vert is? What i m really not sure about and gave me "various" results: -33 33 vert! What? how much? why the hell didnt they mention! -Poles seam to be taken on the midlle pixel of first and last row.That s an average.... -Stil experimenting for the last 33th column... and texture that wrap ok.... Still exited by sculpted prims! =)
Blakar Ogre Registered User Join date: 18 Mar 2006 Posts: 209	06-05-2007 11:52 Faces: there are 32 faces. The seam is a face connecting the first and last columns of pixels Poles: The poles are the pixels on width/2 at top and bottom. As it counts from 0 that means the 33th pixel in a 64x64. To really have all the info please read http://wiki.secondlife.com/wiki/Sculpted_Prims:_Technical_Explanation
Strife Onizuka Moonchild Join date: 3 Mar 2004 Posts: 5,887	06-05-2007 15:06 Just a friendly reminder that this is the correct forum for discussion of sculpted prims and things are much nicer when everyone is civil. _____________________ Truth is a river that is always splitting up into arms that reunite. Islanded between the arms, the inhabitants argue for a lifetime as to which is the main river. - Cyril Connolly Without the political will to find common ground, the continual friction of tactic and counter tactic, only creates suspicion and hatred and vengeance, and perpetuates the cycle of violence. - James Nachtwey
Magicrat Voom Registered User Join date: 4 Jun 2007 Posts: 1	Problems with texture on sculptie 06-07-2007 07:45 Hey I created a head like sculptie using Wings3D and the exporter and uploaded it to SL - no problems. I then created the texture map by exporting as .obj and using UVMapper to create it (using z-alignment and x-offset of 0.5). Painted it with Photoshop and used 3D Canvas to preview it. Everything looks great and properly aligned. The problem I have is that when the texture is then uploaded to SL and applied it is stretched and so not aligned?? I had to change the rotation, etc of the texture but that's not a problem. Do you have to use x or y-alignment when creating the texture map in UVMapper instead if the z-alignment I used?? Or am I missing something more fundamental. Thanks for any help.
bebop Kohime Registered User Join date: 16 Mar 2007 Posts: 2	scaling before upload sculpie textures 06-07-2007 11:15 From: Omei Turnbull 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. 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#post1533245/8/20/183764/12.html#post1533245 for an example of what this can do, and why I suggest 128x128 over a larger size. OMG what a difference puting the bitmap into photoshop and changing it to 128x128 tga before upload made very large amounts of detail was restored thanks very much for this tip cheers

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