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Is 120k / 150k prims enough?

Posted: Fri Jan 01, 2021 3:20 am
by Snoots Dwagon
When setting up a region, one naturally wonders how many prims are going to be needed. Advanced worlds allow 120k prims. Megaworlds allow 150k. Since 150k is only 30k more than 120k, is that enough for a Megaworld? Is 120k enough for an Advanced world? There's no definite answer, but I have a couple of good examples which indicate YES, it is probably more than enough.

I have my own Opensim server sitting in my living room. It's amazing what one can do with a 12-inch fast laptop-- in this case run 50 regions on two instances. The screen is visible any time I wish to look at it, allowing one to see a lot of things that happen behind the scenes with Opensim.

My server handles two 5x5 VARS (25 regions each, 50 regions total). It works fine. (A VAR is the equivalent of a multi-region World on Kitely.)

ELVENSONG
One VAR houses two complete world themes. At ground level is ElvenSong, which is fantasy-themed. It contains the home and historic builds of an ancient group called Elf Clan, my own home Dwagon's Keep, which is a large, fully-furnished castle. ElvenSong also contains a lush giant tree-home for the Poetry guild, also fully furnished, the Elven Gardens, the Thirsty Dragon Tavern, the Elf Clan Museum (a really large, high-prim structure), and Pirates Cove... an area containing several full-size ships.

In high sky ElvenSong is another "world" called Replicant City, running on the same instance. This is a multi-genre science fiction museum, absolutely packed with interactive builds... including a Star Trek museum, Doctor Who exhibit, TRON museum, Steampunk Museum, a full-size Firefly spaceship, and a whole lot more. Surrounding Replicant City are nine full size Star Trek starships with all the goodies.

In short, ElvenSong is one of the most packed-to-the-gills VARs you will ever find on SL or OpenSim. And while the majority of ElvenSong creations are pre-mesh period (thus very "primmy")... the entire VAR only requires around 72,000 prims. On Kitely that would leave 48,000 prims still available.

FRANKENSTEIN
This 5x5 region started out as an experiment. Basically, I wanted to know how much stuff I could cram on a 25-region VAR and still remain functional. So just for fun I shopped the Internet and found every free OAR that I could locate. I rezzed each OAR individually and chose two dozen of my favorites. To these I added my own stuff which includes Frankenstein's Castle, a region-size race track, carnival area and more. I rezzed all of those fully-developed OARs and creations on Frankenstein; it is packed from one end to the other. A person would have to work really hard to pack a world harder than I packed Frankenstein... because doing so was the original goal. (Turns out I liked the "experiment" so much that I decided to keep it online. Insanity can be fun.)

Total primmage on Frankenstein: around 88,000 prims. On Kitely this would still leave 32,000 prims free on an Advanced World. Now add to that 30,000 more prims on a Megaworld. That's a lot of prims still available.

MESH AND LI
On Kitely we have a boon to us that very closely amounts to a gift from the grid owners: Mesh is counted by LI rather than vertices. So if you have a mesh building that is the equivalent of 150 prims but it only shows 10 LI, that's all that Kitely counts. This is an intentional decision by Ilan and Oren and it's a generous one. What this means is that with judicious use of mesh, we can put a whole lot more on a world than just the listed prim allowance. The lower the LI of a mesh... the more stuff we can stick on our world. What might otherwise require 10,000 prims might be done in only 250. Kitely has openly stated that's totally okay with them. It's a great policy for residents. So when Kitely allows 120k or 150k prims on a world... mesh is something to consider.

But even without mesh, one would have to be really bent on stuffing a world full to top 100k prims. I fell significantly short of 100k prims on both ElvenSong and Frankenstein... and they are very packed worlds.

So those are my findings, based on two "high-prim" worlds on my own server. And I didn't even take major advantage of mesh on my worlds. My opinion: 120k and 150k is a lot more than it sounds like. If someone ever reached that 120k ceiling... I'd really like to see what they did that required that kind of prim usage. :mrgreen:

Just my post-for-whatever-value. Be well everyone, and stay safe.

Re: Is 120k / 150k prims enough?

Posted: Fri Jan 01, 2021 1:49 pm
by Tess Juel
Snoots Dwagon wrote:
Fri Jan 01, 2021 3:20 am
So those are my findings, based on two very-packed worlds on my own server. And I didn't even take major advantage of mesh on my worlds. My opinion: 120k and 150k is a lot more than it sounds like. If someone ever reached that 120k ceiling... I'd really like to see what they did that required that kind of prim usage.
When I made Skogholmen ( viewtopic.php?f=25&t=3199&p=28307&hilit ... men#p28307 ) I used 446 prims to fill up a 4x4 with quite dense forest and a fairly elaborate road system. I never got around to add undergrowth, rocks and other details but even with that, I don't think it would have ended up at more than 2,000 prims and certainly not anywhere near the 5,000 I had budgeted for.

But land impact/prim count doesn't really mean anything anymore (except for the load on the assets server) because as you said:
Snoots Dwagon wrote:
Fri Jan 01, 2021 3:20 am
MESH AND LI
On Kitely we have a boon to us that very closely amounts to a gift from the grid owners: Mesh is counted by LI rather than vertices.
Each mesh can have eight faces and although you run into problems before you reach the theoretical 65,536 tris, you can certainly have 30,000, 40,000 and even 50,000 tris in a mesh.

So with 150,000 meshes, you can in theory have 1.2 million textures and 4.5 billion tris. If you have as much as 1/100th of that in your sim, the prim limit is the least of your problems.

The fact that opensim's prim count ignores mesh complexety and pixel count, doesn't mean they don't matter. They matter a lot because all those tris and pixels still have to be loaded and rendered!

I don't think there are many modern AAA games that use more than a million tris and 1 gigapixel of textures and other surface maps (that's the equivalent of 1,000 1024's or 4,000 512's). We have a higher tolerance for low fps on opensim of course but we also have to account for loser spec computers than what those games are made for so we really don't want to go much higher and preferrably considerably lower. You can get away with even twice as much but don't bet on it. This is regardless of sim size btw. If the meshes are spread out across a big 4x4 or 16x16 you may get good fps even with more since not everything will be rendered at the same time but everything will still have to be loaded.

Oh, and before somebody corrects me: Yes, vertice count is far more important than triangle count but those two numbers are usually fairly closely correlated and the tris are easier to count.

Re: Is 120k / 150k prims enough?

Posted: Fri Jan 01, 2021 4:14 pm
by Snoots Dwagon
Thanks Tess. You covered something I didn't touch on in the original post: just because we can do something doesn't mean we should. :)

Our abundance of prim count is great, but as you say, all of those graphics have to be rendered on the user end. An example I've often used is painting and sign textures. If one wants to build a museum full of hundreds of paintings, it is better to place them in individual rooms and connecting hallways in order to limit the number of textures visible at one time. If you put all of those paintings inside one circular room... they're going to try to rez at the same time and will have significant impact on even high-level graphics cards.

When we build a world, the prims we use most likely have textures on them. A lot of those prims might contain scripts. Some of them may be physical. Prims themselves don't lag, so the prim count is not nearly so important as how we use them.

I was very conscious of this when I started building Replicant City in 2010. Since I knew it was going to basically be a 3-D virtual museum, it was essential that it be designed to not overload viewers. It was going to be both texture and script heavy. What I had to be most conscious of was how and where textures were used (especially in the Hall of Funny, which contains thousands of humorous signs). With careful designing it turned out well, with no discernible lag. Not paying attention to such design could have resulted in a lag-fest nightmare.

So I'm glad you posted. How we use our prims / textures / scripts / assets is indeed far more important than how many prims we have available.

Re: Is 120k / 150k prims enough?

Posted: Fri Jan 01, 2021 9:34 pm
by Tess Juel
Snoots Dwagon wrote:
Fri Jan 01, 2021 4:14 pm
If one wants to build a museum full of hundreds of paintings, it is better to place them in individual rooms and connecting hallways in order to limit the number of textures visible at one time. If you put all of those paintings inside one circular room... they're going to try to rez at the same time and will have significant impact on even high-level graphics cards.
A friend of mine, Hattie Panacek - the brilliant medieval/steampunk builder, told me somebody once did something like that in SL long ago. A huge arts museum with replicas of the most famous paintings in RL, all in glorious 1024x1024 resolution. Apparently it was absolutely spectacular. The only minor snag was that nobody ever got to see it because their viewers crashed long before the textures had finished loading.

Another example of extreme SL overload I witnessed myself, was when I took another firend of mine to Apple Fall's store. My friend was using SL Go (an online game streaming service for SL for those who don't remember it) at that time so thee couldn't possibly be any render load issues, right?
Wrong! The big, strong SL Go server with it's big strong state-of-the-art gpu only managed to render less than half the content before it gave up. (I have to add: although Apple Fall is SL's King of Lag his best builds do look fantastic and may well be worth the fps reduction they cause. Just don't put too much of it in the same place and keep them indoors so they don't lag down a wide area. Oh, and when (not if) you come across some of his works on opensim (with a different name listed as creator), stay away. It's copybotted.)