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Mesh vs Sculpt LI 64x64 Mesh Terrain


Dominic Damiano
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First off I am a blender noob.

I am trying to create a 64mx64m mesh terrain for a small island area. I created a heightmap and used displace in blender to mold the plane. The plane was subdivided by 63 giving me a 64x64 mesh. This gives me 8192 Tris and 4096 faces. I am 100% sure that the mesh can be optomised and decimated but I do not want to distort the smooth curves. 

With a UV unwrap this gives me a LI of 675 on the download. This seems insane for such a simple plane with round curves.

If i remember correctly sculpties at LOD3 have 1024 faces. So theoretically I could make the same shape with 4 sculpts and maintain the LOD.

I tried to divide to mesh into a smaller size to see if that was the problem. If I divide the 64x64 into 16x16 pieces I end up with 512 TRIS per piece and a LI of 15 per piece. This brings the Li down to 240 still much too high. I then went down further to 8x8 pieces. This dropped the LI down to 64. I feel that this is still too high and would require much more work than necessary.

Any tips or input would be appreciated

 

.

 

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Maybe I shouldn't offer any advice here since I'm about to launch my own series of mesh islands... :matte-motes-wink:

But making a mesh landscape without the LI getting out of hand is all about decimation. For a build like this, the relation between triangle/vertice count and LI is very simple and the more detail you have, the higher the LI. No secret tricks at all here unfortunately, it's all about deciding which details you need and which you can do without. However, if you start with a straight grid, there's bound to be some vertices you can remove without altering the shape at all. A limited dissolve with max angle set to 1 degree should take care of that and reduce the LI considerably. And of course, smooth normals will help a lot - but you'll need to use those anyway so I suppose you've already figured out that.

Sculpts, although technically als mesh, is processed in a different way than mesh so the land impacts can't be directly compared. Sculpts will always be a better option than mesh for purely visual landscapes. But if you want to be able to walk on the surface, you'll need lots of physics prims for the sculpt and you'll never ever get uit exactly right. With mesh you can get a walking surface that matches the visual model exactly with no additional LI

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Agree it is all about making it BASIC. I had some 64 x 64 land terrains that were maybe 58LI? I forget now. A friend made something similar for 17li. Mine were "nicer" with smoother curves but I went with the 17 LI as I had TONS of them on many levels and that adds up. So divide you next mesh into MANY less quads than the ones you have now BEFORE raising and lowering the terrain and get rid of any edge loops you don't need etc. That's all it is.

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Thank You ChinRey

I wouldn't worry too much about competition :) I can visualize it but I am no artist. I however am pretty awesome at making organic height maps in PSP. I will try today to divide the area into quads 32x32 and optomise them as much as possible.

 

On a side note. Is there a simple way to divide an object in Blender into equal chunks. It is a pain to count the faces and use the laso select. I would reather just enter the numbers and have it divided into 4 objects by coordinates.

 

On a side note....am I doing something wrong because my download sizes are crazy when compared to the physics. 

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Dominic Damiano wrote:

Thank You ChinRey

I wouldn't worry too much about competition.

Me neither, I was just joking. With a few expections, SL content creators work not for the money they can make but because they love the work and love to share their experience with each other. :)

 


Dominic Damiano wrote:

On a side note. Is there a simple way to divide an object in Blender into equal chunks. It is a pain to count the faces and use the laso select. I would reather just enter the numbers and have it divided into 4 objects by coordinates.

Not that I know of but there are some useful tricks to make the job easier.

It's a good idea to plan ahed a little. If you start with a grid, assign each section to a separate material before you spilt it up into too much segments and before you start moving the vertices around.

To line up the vertices along the split lines, use the edge selection tool to select the entire edge (oftenyou can just alt-click on one of the edges for that) then type SX0 or SY0, depending on which axis you want them lined up along.

 

Edit:

Sorry a serious typo here. Instead of " the money they can make" read " the money they can't make"

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Chic Aeon wrote:

Agree it is all about making it BASIC. I had some 64 x 64 land terrains that were maybe 58LI? I forget now. A friend made something similar for 17li.

It's important to remember that the ground will be covered with lots of lovely items anyway. What's the point of wasting LI on details nobody will ever see?

The latest mesh ground module I've been working on has an LI of 2. Not muc detail of course, most of it is just a big gently rolling hillside, but it's goign to be covered with a lush, dense forest so the details would have been lost in the vegetation anyway.

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A sand beach...

Maybe I should invite you to take a look at my workshop: http://maps.secondlife.com/secondlife/Coniston/175/140/2000

It used to be a lush green field but was hit by global warming last week so now most of it is a desert. One corner - a little over a quarter sim all in all - has been converted to a proper desert with 20 LI worth of sand dunes. It's just a quick spur-of-the-moment build. Texture alignment is way off and I should have chosen a rounder shape for the sand dunes (which would have added about 10 LI to the build) but it still should give you a good idea what is possilbe to do with relatively low LI mesh landscapes.

Come to think of it, you don't really have to come visiting if you don't want to, I posted some pictures of it in my profile after I built it. Let mes se....  Here they are!

https://my.secondlife.com/chinrey/snapshots/55155798128cc91d77000001

and

https://my.secondlife.com/chinrey/snapshots/5515595ff8a1ec686a000001

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Keep in mind, if you split the mesh into pieces you may want to unify the vertex normals along the object borders. Or you will have to deal with shading seams if the split is on non planar sections of the mesh. Can be a bit problematic with Blender, since it is still lacking vertex normal editing functions natively.

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"problematic with Blender, since it is still lacking vertex normal editing functions"

Aquila just told me the latest Blender, 2.74,  may have the required functions. I have downloaded it so I can try that out. Meanwhile, the method I described before (where you add overlapping faces of the next piece, assign them to a new material and delete their <polylist>s from the collada file) does seem to work. Here is a picture of part of the same 64x64 quad mesh separated into 16v 16x16 meshes, with the overlap technique at the top, and without it at the bottom. Weights are not affected. It was made shiny to ahow up the seams better, and the top one isn't quite perfect; you can just about make out a bit of seam if you look very closely.

smoothborders.jpg

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arton Rotaru wrote:

Keep in mind, if you split the mesh into pieces you may want to unify the vertex normals along the object borders. Or you will have to deal with shading seams if the split is on non planar sections of the mesh.

Hmm, I've never noticed that. I did a full sim landscape in Blender, split into 64x64 m pieces and reassmbled on the beta grid. Didn't notice any seams at all - except for some misalignment caused by SL's lack of precision. Maybe it was masked by the textures I used?

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ChinRey wrote:


Maybe it was masked by the textures I used?


Possibly. On such a large scale of a fullsim mesh it might not be too obvious anyway. Though, when a mesh is cut into pieces, the normals are recalculated on each piece, and the result will be a hard edge, if the surface isn't planar.

I would recommend to upload such things always in one go. On the picture below is a fullsim mesh with unified normals along the borders, uploaded all at once.

FullsimMesh01.jpg

And since the thread is about Land Impact. This one counts 55, with the road cut in. High LOD only down to the Lowest, and Physics. The whole thing is around 1000 tris. Without the road it could be even lower I guess.

FullsimMesh02.jpg

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Drongle McMahon wrote:

 

Aquilan just told me the latest Blender, 2.74,  may have the required functions. I have downloaded it so I can try that out. Meanwhile, the method I described before (where you add overlapping faces of the next piece, assign them to a new material and delete their <polylist>s from the collada file) does seem to work. Here is a picture of part of the same 64x64 quad mesh separated into 16v 16x16 meshes, with the overlap technique at the top, and without it at the bottom. Weights are not affected. It was made shiny to ahow up the seams better, and the top one isn't quite perfect; you can just about make out a bit of seam if you look very closely.

 

Nice workaround, as always! Sounds a little bit cumbersome though. :matte-motes-delicious: Looks like 2.74 got that Edit Normals Modifier, which adds some basic editing. Not sure how useful this will be. Looking forward to see some tests from you. :matte-motes-sunglasses-1:

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"Looking forward to see some tests from you."

I had a go. It's  a VEERY complicated modifier called data transfer, which appears to be able to copy just about anything between objects with all sorts of ways of saying what goes where and how it's mixed with the existing whatever. Should be reasonably simple for just normals in this context. I could do it inside Blender and the seams disappeared nicely, buit so far I couldn't get that result out into the collada export. Finally it crashed :matte-motes-confused: I'll keep trying. Meanwhile, if anyone else has got it done ....

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ChinRey wrote:

Yes I would recommend uploading meshes like this as one piece too.

But for a full sim, how do you upload a 256x256 m mesh to SL?

As always, I hit the Upload button. :matte-motes-wink-tongue:

Seriously now. Since each piece is only 64x64 and the maximum size is 256x256 it work like any other upload. The only limit is that pieces need to be no further apart than 240 meters. That's measured from the pivot points though. So with 64x64 pieces those are well within that limit too.

There is only a little bug where 64m meshes end up like 63.900 or something. I just select the whole thing inworld (512m Draw Distance) and stretch it to the max.

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I was able to export the meshes with the copied normals as OBJ, and imported them into Max. From there to DAE. That worked. So it should also work with the Standalone Autodesk FBX Converter (OBJ > DAE). (To lazy to install that.)

Although, it seams like it sets the normals on the entire mesh in the same direction of the copied normals. Maybe there are some settings to overcome that? I don't know.

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Yes. The obj exporter does export the transferred normals, but the collada exporter doesn't. It uses the vertex normals that you see with the first normal display button "vertex normals", as oppose to the new "vertex per face normals" that you see with the second button. The latter are the transferred ones. It doesn't seem to matter whether you do "Generate Data Layers" and/or apply the modifier. Re-importing the obj that has the transferred normals still doesn't get them into the collada export.

I guess we will have to wait for a word from Gaia to see whether the exporter will be modified, or whether we will have to resort to the sort of workaround you suggested.

By the way, you can use a vertex group in the box at the bottom right to restrict the vertices that receive the transferred normals.

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Drongle McMahon wrote:

 

By the way, you can use a vertex group in the box at the bottom right to restrict the vertices that receive the transferred normals.

Ah alright, that might do the trick then. I haven't used Blender since 2.49. :matte-motes-nerdy: Just wanted to check out where it stands now regarding vertex normal editing. As far as I can see, it has still a long way to go. But it's at least something.

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Still learning and playing. As I get more familiar with Blender it becomes easier to make shapes. I still cannot get the LI results that I am after. With a 64x64m mesh keeping only a small portion of the semi smooth curves I still end up with a LI of ~200. I feel that I am going to have to learn sculpties all over again. Or my texturing skills are garbage.

 

Untitled.jpg

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Thje problem is that with objects that size you get little or no LI benefit from the LOD meshes. So it is imperative to minimise tyhe triangle count. The one in the picture is still high. I can see a lot of places where you have many quads in a row that could easily be fused. Also, you have at leat one more row of quads than you need for the rounded edges. Note also that the huge ngon in the middle will get triangulated too. So minimising the complextity of its outline will be beneficial.

You will run into another problem when you use this mesh to make a triangle-based physics shape, essential for proper walkability. For that, small and narrow triangles push up the physics weight hugely. So for a mesh to keep LI down, the triangles should be as large as possible.

Here is something a bit simpler, in Blender, then in SL. Its LI is 16 at 64x54m, download weight 16.3, triangle-based physics (not Analyzed) from the high LOD mesh, physics weight 9.5, auto LODS. It has scope for more optimisation.

lscpx2.jpg

lscpx1.jpg

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That is absolutley awesome. Can you make a tutorial for that? My method of aproach was to use a height map. This gives me tremendous flexibiliy for organic shapes and curves and also allows the opportunity to download a real world terrain.and put it into a mesh.

Can the displace modifier be used to get the results you achieved, or is my approach wrong. 

My Steps:

Plane 64x64
Subdivide 63
Displace with BMP
Boolean with Plane
Decimate Planar 1deg

 

It would be nice to work with heightmaps but maybe this is just not possible.

Beautiful work you have done. Everything is so even and organized.

 

 

 b2.jpg

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We have plans to add custom normal export to the Blender Collada exporter. But i can not yet tell when exactly this will become available. I hope for Blender 2.75 but there are soo many other things to be done as well :matte-motes-dont-cry:

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