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Loki Eliot

Loki's Adventures in creating a mesh object for SL!

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Loki Eliot wrote:

I appreciate all your advice and encouragement. Is their a tutorial that explains LOD and how to prepare for it when uploading a Mesh to SL? it seems a real vital part of Mesh, yet i don't really understand it and im sure others just starting out never even heard of it.
:)

Rez a prim cube, and zoom your view close to it.  Type Ctrl-Shift-R to go to "wireframe" mode, which shows only the edges of a shape and not the textures.  (you might need to turn off lighting and shadows to see it).  You will see it has 3x3 squares on each side, or 18 triangles per side.  Now zoom out, and it will reduce to 2x2 squares, then 1x1 square.

Most graphics engines, including SL, reduce the detail of an object when it gets small on the screen.  That lets them avoid rendering details that are too small to see and run faster on any given computer.  These are called "levels of detail", and have always happened for prims, textures, and sculpts.  With a mesh, you have the option of defining custom versions of the model for each of the 4 available levels (High, Med, Low, and very low).  If you choose not to make custom ones, the upload window will take your model, and simplify it for the lower levels by some automatic method.  Usually you can get a better looking and lower PE cost result making the different levels by hand.

Most better 3D programs have a function like "Optimize" (3ds Max), or "Decimate" (I think, for Blender), which will take a model and simplify it.  So one method to make the LODs, is to save your highest detail version, then apply the simplify function, followed by hand cleanup in places the automatic process didn't do what you wanted.  The standard reduction assumes a factor of 4 in triangle count per level, but you can do it differently, or use the same model for more than one level.  That will affect the PE cost, but it's up to you.  Save the simplified model as your medium level, and repeat to make the low and very low versions.

In the upload window you can point to each of your LOD files, so you would be uploading up to 4 versions of the model to create 1 mesh asset with 4 LODs.  One thing to note is all the versions of the model need the same number of texture surfaces, although they can be mapped differently.  For example the  Small Palm Tree  I made has three textures.  One is the leaves and stalks seen at close range.  The other two are alpha images of the model seen from two sides (rendered in Max).  That is placed on simple triangles that intersect for the lowest level of detail.  Replacing a model with a picture of the model on a flat surface is called a "billboard", and it is a way to get a very low triangle count.  Since I need all 3 textures at all levels of detail, I have two triangles buried under the stalks to hold the alpha images on the higher levels, and at the lowest level put the leaves and stalks texture on a spare triangle that is hidden.

For some types of models, the auto-LOD in the upload window is good enough.  It's easy enough to start with the high detail model, and see how it looks, and only make custom levels if it needs it.

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So when i upload a model to SL, im in fact uploading FOUR models either because the UPLOADER is constructing 3 more for it, or ive taken the time to construct 3 extra versions of the model for the LOD factor?

I wonder if SL can give out qualifications in 3D modelling design after Mesh goes live LOL!

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Yes, there will be 4 models.  With prims the LOD versions are pre-defined in the software, because every box prim is the same as every other box prim in terms of geometry.  With scuplts, my understanding is the LODs are done by discarding every other row and column in the sculpt texture.  I'm not sure about that since I never learned to make sculpts.

I don't know about getting a certtification, but knowing how to make 3D models is a useful skill outside Second Life, just like knowing Photoshop.

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OK so armed with new knowledge about LOD layers i set forth to do an experiment.

I had wanted to do a new Monster Dog character to let loose on my island once Mesh goes live, so with that in mind i used that for my LOD experiment. 

I created the Dog Toad (or Tog) using Silo for mac, then ported into Blender 2.5. Using the 'Decimate' modifier i reduced the 'triangles' or as its called in Blender 'face count' . I noticed in the Uploader there is a LIMIT to how many triangles an LOD layer can have so while DECIMATING in blender i kept an eye on how much the FACE COUNT was.

So i exported the first LOD layer, decimated the model again, then exported the 2nd LOD layer and so forth untill i had 4 models each representing a Layer of LOD, each with less Triangles/Face Count, from high detail to lowest detail.

I used photoshop to  create my Tog's texture.

I uploaded a Tog using my LOD layers and then one with UPLOADERS AUTO LOD generator. The AUTO generated version Prim Equivalence came in at around 11PE, where as my custom LOD came around 4PE.

I dont know weather im not doing something correct when using the Auto LOD generate, but i was surprised how much difference there is between Newb mode and  manuel mode. I will ad that i also tried uploading the Tog with the AutoLOD Generate and it came in around 5PE, so i'd assume something is vitally borked in the uploader for the latest Mesh Devs when it comes to Auto LOD Generation.

Only issue i have, and have no clue about fixing is the texture i made disappears when the Tog degrades to a lower LOD layer. Anyone care to enlighten me to why that is?

The_tog.jpg

 

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I like your Tog ;-)


Loki Eliot wrote:

Only issue i have, and have no clue about fixing is the texture i made disappears when the Tog degrades to a lower LOD layer. Anyone care to enlighten me to why that is?

Maybe you have unintentionally used 2 different materials for your lod meshes ? Ensure that the texture faces in the different LODS match one to one to each other...

 

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I like the Tog too. Better keep away from your island though. It's a bit scary. Normally the texture (for each material of) the high LOD is re-used for the lower LODs. It turns out* that the decimate modifier completely removes the UV map. So I guess your lower LODs have no UV map?. In the exported collada, there simply is no texture coordinate info. Using such a file at the highest LOD can have very strange effects with the current viewers (SH-2045). Maybe it's not so devastating at the lower LODs. However, it would appear that using decimate you will have to do a new unwrap and adjust the UV map to fit the texture properly to the decimeted model, for each LOD. (I do all my decimation mabually, but still have to do a lot of work adjusting the UV map).

This is all Blender 2.49b. May be different for 2.5?

 

 

 

 

 

 

 

 

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When you are on blender 2.4 you can use the poly reducer scripts. Both reducer scipts (available in edit mode under Mesh -> Scripts -> ...) preserve the UV-map (more or less).

BTW: The decimate modifier also "forgets" the UV map in Blender 2.5

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In your UV map window, select all the UVs and press "P" to pin them. Now you can remove vertices and unwrap again. The new UV map will be laid out as before, minus the vertices you removed.

Gaia, I did not think to check the scripts!! Doh! I will have to try that.

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Vivienne Daguerre wrote:

In your UV map window, select all the UVs and press "P" to pin them. Now you can remove vertices and unwrap again. The new UV map will be laid out as before, minus the vertices you removed.

What a nice idea! I'd love to add that tip into my LOD tutorial ;-)

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Vivienne Daguerre wrote:

In your UV map window, select all the UVs and press "P" to pin them. Now you can remove vertices and unwrap again. The new UV map will be laid out as before, minus the vertices you removed.

 

oh, that looks like a great improvement of the workflow.

I wish Blender 2.5 had that scripts from 2.49, they work on the selected parts only, instead of decimating the whole object

 

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Blender 2.49 gives me such a head ache, i hate using it. But i did use the poly reducer, no idea what all the extra numbers and stuff in the poly reducer window meant but managed to export another Tog that retained its texture when changing LOD layer. Unfortunately it added TWO extra Prims to the Togs PE, so i guess more experimenting is needed. Thanks for the advice :)

The Whole Blender 2.49/ 2.5 issue is such a pain in the ass for newbs. 

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Vivienne Daguerre wrote:

In your UV map window, select all the UVs and press "P" to pin them. Now you can remove vertices and unwrap again. The new UV map will be laid out as before, minus the vertices you removed.

Gaia, I did not think to check the scripts!! Doh! I will have to try that.

 

 

Where you referring to Blender 2.49 with this advice?

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Yes the pin function is in Blender 2.5 but wen i unwrap, i get a big triangle in the uvmap editor, so i guess work flow does not work in Blender 2.5.

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How exactly do you unwrap ? The pinning is only available for the default: Unwrap -> Unwrap

All other unwrap methods (projection, smart, etc..) do not take care about the pinning...

Or maybe you found a bug ?

 

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I've been learning how to create Mesh objects for a couple months now and by jove it's not easy. 

The creative side is ok, it's just the technical side is SO fragmented and this is NOT Linden Labs fault. The 3D modelling world as a whole is a nerdy one and is no way in a position for mass uptake by the general public.
You have major 3D package software that i cant afford to use, so cant comment on wether Z-brush3Dstudio max or what ever else has a more complete and user friendly work flow. For the Mac there is also cheaper solutions such as Silo andAC3D to consider but the majority of newbs to Mesh will no doubt find their way toBlenderas its FREE.
The problem with Blender though is its currently very slowly going through a transition of being ridiculously lousy with UI (2.49) to a more intuitive easy to use UI (2.5). I found it easier to get to grips with Blender 2.5, thats the whole point of Blender 2.5 but when it comes to using it for making SL Mesh you will soon discover vital features that make Mesh easier and more efficient are strewn between the two version of Blender making it a very frustrating experience to learn. Although it is free and they guys working on it are doing it out of their own pockets and through donations so Kudos for them really....... just wish they worked quicker to implement the missing features :-p

I have found that to make a good prim efficient Mesh for SL, i have to use multiple applications, porting from one to the other. These 3D apps do not seem to have all in one. Some Like Silo don't even support the Collada format, others lack Poly reduction, and whats worst is that these programs have been around for years. 
So anyway, if you are thinking of making Mesh in Second life, i have made a list of subjects i've had to learn regardless of which 3D software i've been using.
1. Learn how to create Mesh objects, learn about extrude, vertices, faces, edges and manipulating them.

2. Learn about subdividing and modifying.

3. learn about unwrapping UV's, texturing & multiple faces.

4. Learn about Levels Of Detail (LOD) and how to decimate/reduce faces on your model.

5. Learn how to weight your Mesh and rig it for wearing.

6. Learn about Mesh Physics and how to apply it to your mesh.

7. Learn How to use the SL Mesh Uploader and how it deals with LOD and Physics

8. Learn how to keep Prim Equivalence LOW. (not as easy as you may think)


Lets not delude any SL users here, it's not as simple as rezzing a prim, texturing and linking , you really do have to learn 3D video game modelling. There are university courses lasting two years teaching the stuff you have to learn here. But there are some amazing talented and generous Users in SL who have given me a lot of help and advice to learn on the SL Forums. 

 

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You clearly have an aptitude for it Loki, and a good artistic eye. Without the artistic ability, all the technical know how in the world won't help you. I have enjoyed following your progress.

It is not simple to learn and it requires an investment of time to do so. Programs you need and tutorials are freely available on the web, so it is not necessary to lay out a huge amount of cash. This is good news.

It is also good news that you and I were able to learn how to do this. There are many of us who do not work as professionals in the 3D field, probably most of us I would guess. Perhaps not everyone can learn this, and surely not everyone will be willing to put in the time to learn this. However, it is possible for those who have an aptitude for it and are willing to put in the time and effort.

One thing I love about Second Life is the community. People are friendly, open and willing to help. I have met new people in the mesh beta test and I am happy about that. Without their help, I would not have been able to do this!

Thanks to all of you out there! You rock!

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Loki, I think you correctly summarized the basics that someone has to learn.  Fortunately for the first 5 items there are extensive tutorials online for any popular 3D program.  For example these videos on Blender 2.5 Fundamentals at 3D Buzz:

Tutorials 1-11

Tutorials 12-25

So what I think we need is a wiki page on "How to learn mesh" that points people to the specific things they need to learn, and where to find it.  Like for the above set of tutorials, tell people "For Second Life, watch videos 1 to X, and export your model with these settings"

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airships.jpg

Finished upgrading my Aiship to Mesh, this is the forth itteration of my Icarus Airship. The previous version was made from Sculptys & 1 Mega Prim and came in at 24 prims. This Mesh Airship came in at 38 PE and could go higher once i place Sit pose pims into it. 

I've been told as long as the Physical Weight of the object is below 32 it does not matter about the PE for vehicles. There does not appear to be anywhere to find out an Objects Physical Weight post Uploader so i'm just adding more and hoping for the best at this point :).

icarus4.jpg

 

Mesh_sculpty_airship.jpg

 

While creating this Airship i learnt alot more quirky things  about mesh. I assumed complex Mesh shapes would have higher PE, but infact parts like the Ships wheel and the engines came in at a far lower PE than say the Baloon. It's not the complexity of the shape, its the size of it. Just enlarging the Ship by an inch can cause the PE to rise considerably.

I also did alot of playing around with the uploader now that i understand the LOD layers and the Physics part of it. The Lowest LOD layer can always be set lower and some parts of the Airship could use the lowest LOD's Physics shape almost as if it was phantom.

Things im still not sure about is the difference between 'Prim' & 'Convex HUll' Physical settings, whats the perpose of these two settings?

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Convex Hull = use a single convex hull for the whole mesh.

Prim = Use the decomposed (Analyse) physics shape if it's there, otherwise use the triangle-based physics shape.

If you don't supply a physics shape, you can't select "Prim".

If you use "Convex Hull", you can't go inside (any concavity of) the mesh.

PS. Lovely airship.

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It's now been Four years since i started this thread to learn how to make mesh. I thought i would give a little update to show how far i've come since then. I just want to thank everyone on this thread who gave me advice and encouragment without which i would be not doing what do now :-)

 

https://lokieliot.sketchfab.me/work/92ca0e68a35e43149e442371ef5c0d8b/in/other-stuff

lokiAnime.jpg

 

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It's been 8 yeas now. Just want to say thank you to everyone who gave me tips and encouragement at the start :)

 

LokiSansar2.jpg

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