Large Mesh Landforms

[Anna Nova]

I offer this just in case it helps someone.  Not looking for help, but feel free to enlighten me....

I needed a large landform for our parcel at Ogilvie.  We are building a very complicated mesh house, with a basement, and I hate landscaping in SL, whatever you do something always screws up nearby.  The answer for me is to push the whole parcel to minimum, and make the land in mesh.

Only this time I got terrible yet subtle distortion that took me a while to work out.

It was uploading different from how it looked in blender.  The problem is prim-size limits.  I had made a mistake in blender of making something bigger in X than the maximum 64 meters, so the uploader squished it, and stretched the Y from 61 to 64, and the X from 70 to 64.  I guess this behaviour might benefit someone, I would prefer it to say 'No!', rather than the silent squish.

So the answer was to split the landform into two, and upload them separately.  Uploading them as a linkset doesn't do it, you get the same squish.  Each upload has to be 64x64x64 maximum.

There is a benefit in doing this.  The LI for the linkset went from 7 to 4  (Download 3.5, Physics 3.0, Server 1.0), and this is using High as the physics, and no analyze.  The two parts can be linked in-world.  The disadvantage is that the upload fee base of $11L has to be paid twice, but the total was only $24L

It was worth the hassle to discover all this.  But, Thank you for Beta!

Anna.

[arton Rotaru]

The 64m limit does apply to individual objects only. You can indeed upload multiple meshes which together exceeds that limit in one collada file.
This works with the official Second Life viewer. Which is what I always recommend to use to upload mesh. Although even the official viewers mesh import isn't bug free (the maximum size for multi mesh uploads is currently 240 x 240 x 240 meters), third party viewers may have additional bugs which are screwing up mesh uploads. Which could explain the rather strange non-uniformly squishing to 64x64 meters.

[Chic Aeon]

While I almost never (NEVER) use the official viewer it is good to know about the linkset maximum.   And really an extra few lindens isn't a big deal if it works!   My  question might be "can you WALK on the landforms?"  It might not be important but that is a really low land impact for a huge piece of mesh LOL.    

[KatyProxima]

Note that Firestorm 5.0.1 also has this bug and can't be used for uploading multiple mesh objects, because of the incorrect bounding box problem viz https://jira.phoenixviewer.com/projects/FIRE/issues/FIRE-20547?filter=allissues

They say it should be fixed in FS 5.0.2, but I still use FS 4.7.9, which works perfectly for mesh uploads, with multiple objects.

Anyways the size limitations are huge pain in SL and i don't see any reason why LL insists on it, when even in InWorldz you can upload single mesh 256x256m without any hassle.

 

[ChinRey]

5 hours ago, Chic Aeon said:

My  question might be "can you WALK on the landforms?"  

WIth the high LoD model as the physics it should match fairly well so that's not an issue. And with meshes as big as those, it's very unlikely physics weight will influence the land impact so there's no point saving here.

Here are a few tips for those who want to make mesh landscapes:

• Keep the number of polys down to a minimum - that's the one factor that is likely to affect land impact
• Usually you shouldn't bother with LoD models or physics model. Use the same mesh for them all. Sometimes you can shave off a little bit of LI by simplifying the LoD model but not much and it's hardly ever worth the time and visual quality reduction.
• If you make LoD models, do not under any circumstance change the edges of each segment.
• Don't insist on 64x64 m sections. You can often reduce the LI by using more and slightly smaller sections. I usually go for something between 50x50 m and 54x54 m. Using smaller sections also means it's possible to add an invisible "normal adjustment" face at the edges if necessary and also that you can place the joints where they are as unnoticeable as possible.
• Make sure the dimensions of each segment is an even number of millimeters along each axis to avoid gaps. (This precaution also solves the 240 m multimesh upload issue btw since it means you can easily upload the meshes separately and still be sure they'll fit.)

I've done a few tests and as far as I can see, a well made mesh landscape shouldn't add any noticeable lag. You get a bit of physics load from people walking on the mesh of course but you also save physics load by keeping them away from the ground so that evens out. In theory a mesh landscape shold actually be less physics heavy than the ground but so far I haven't found any measurable or noticeable difference whatsoever.

What may add lag though, are the textures. Cover the ground with a dozen 1024's and you're bound to have problems. The system ground texture system with four blended fairly low res textures is actually very ingenious and with well chosen textures you can get amazingly lively ground with amazingly low texture load.

[ChinRey]

22 minutes ago, KatyProxima said:

Anyways the size limitations are huge pain in SL and i don't see any reason why LL insists on it, when even in InWorldz you can upload single mesh 256x256m without any hassle.

Yes but remember that the people at InWorldz and other independent grids love lag and just can't get enough of it!

Still, I do agree. Just like the the other systems LL has implemented in SL to keep lag down, the object size limit doesn't really do the job very well and quite often it works against the intended purpose.

[Anna Nova]

Chic Aeon, I seem to be able to walk on mine.  And at about the right height too (which is more than can be said for many places, since hover made people lazy).  Interesting info on the Jira in Firestorm 5.0.1 - which IS what I'm using - thanks KatyProxima.  Thanks for the tips, lag doesn't appear to have changed, ChinRey.

Edited April 22, 2017 by anna2358
typos, and removed own-ignorance.....

[ChinRey]

On 22.4.2017 at 9:15 AM, anna2358 said:

Thanks for the tips, lag doesn't appear to have changed,

A well made mesh ground should actually reduce the lag significantly since it will have fewer active polys than the system ground it replaces. I did a simple test to illustrate this and the result is actually quite amazing.

Here is a perfectly flat piece of ground, no items on it whatsoever:

The fps my computer manages to render this scene at is:

48.5

Now, if I cover part of the ground with a prim:

That adds one more texture to the scene which of course adds to the lag. Even so, the fps I get is:

I've always wondered why the sandboxes on the beta grid are so laggy, they're just flat, open system ground surfaces after all. Well, there's the answer: flat, open system ground surfaces are eally bad for your fps.

So here's a brand new lag reduction tip for everybody: Cover as much as possible of the system ground with prims, meshes and even sculpts!