A Thread - All About LOD

[Rick Nightingale]

31 minutes ago, Da5id Weatherwax said:

When an object can be viewed at lowest LOD, usually only outdoors, you are likely to find that using a few (single digits, 8 at the most, usually) triangles to create a planar "impostor" of your object will make no difference to the final LI, the few decimals difference this makes compared to a single triangle in the lowest LOD being lost in the rounding to the nearest integer, but the improvement in inworld appearance being significant.

Absolutely; exactly what I've found myself (I'm really just an amateur, I only sell stuff to fund my SL). I fully agree with everything else you wrote too. You've described my building/testing/optimising process.

I've just checked my house and other buildings on my 256m-long slice of land. Everything I've made stays looking good at 256m away at LOD-factor 2.0. I usually run at higher than that (3 typically) because things I haven't made (like trees) vanish, and I like a long view. The detailed roof edging vanishes just at that point, but otherwise you can't tell. The interior rooms of the house though collapse to a few triangles long before that, for low and lowest, but leave appropriately textured planes behind the windows so you still see a room 'interior' through the window at a distance where it actually no longer exists.

@Prokofy Nevais spot on about the textures too. I learned early on that it makes a big difference.

I've always been prim-poor with whatever land I've had (I remember celebrating when LL increased the allowance years back - I was down to like ten free prims). I guess that prompted me to both learn to make my own mesh, and make it low LI while looking good because it's the visuals in SL that floats my boat.

I doubt that running at LOD factor 4 could damage a PC; there are far worse things (like long draw distance and countless full-size textures) but it does take more server effort, network bandwidth (both of which impact everyone on the sim) and GPU power even if it's not noticeable on a decent PC.

 

Edited October 3, 2022 by Rick Daylight

[Love Zhaoying]

16 minutes ago, Prokofy Neva said:

There are some creators like Hisa and Yugen who provide you with two versions of an item, "Low LOD 4" and "High LOD 2" (the numbers are counterintuitive). And I choose the "Low LOD" for the very simple reason that it is much less land impact and it looks no different to me, and customers don't complain. Most people don't have long draw distance and don't have all the graphics boxes checked.

I don't like being hectored by creators who insist I turn my settings up to 4 for the simple reason that I find this tip really only applies to sculpties (remember them?) which can look an absolute mess unless you have 4. But it doesn't seem to make much difference on *mesh*, *to me*.

And sometimes to me it seems it's more about the texture not being managed (1024 versus 512 which is less laggy and pops into view faster) rather than the vertices.

And now that I've heard that "4" can "hurt my computer," while experts disagree, I put it down to...2. Because I think the really bad view of stuff fixes around 2. And if it doesn't, well, I will look elsewhere.

It's all about land impact. 

I don't tell newbies about LOD. I tell them to put their draw down to 64 until they get better adjusted and figure out how to lag less, then push it up gradually.

I really like how your approach and advice changes over time with what you learn!

[ChinRey]

5 hours ago, Rya Nitely said:

It isn't true that creators/sellers who use a triangle are taking the easiest way out. They do it to keep LI down because that is what sells, and that is what a successful business does

You have a lot of good points, Rya, but I have to correct you here. You do not save land impact by reducing a model all the way down to a single tri. The reason is that once you get a model down to certain point (usually 15-20 tris but it depends on a number of factors) the amount of tri and vertice data becomes so small it drowns in the overhead. Taking the simplification beyond that point won't affect the land impact at all.

This isn't a perfect example since it's four years old and one of the first tree trunks I ever made. But I don't have time to rummage through my whole inventory to find a better one and I hope it still illustrates what I mean.

High LOD:

Lowest LOD:

As you can see, the tree trunk to the left has collapsed into a single tri while the one to the right, with 12 tris, still is identifiable as a tree trunk and has more than enough details to work perfectly well with no noticeable distortions even with LOD factor set at 1.

Now, look at the weights and LI. The one with a 12 tri lowest LOD model:

With a single tri collapsed lowest LOD model:

And yes, in this particular case collapsing the lowest LOD model actually increased the download weight slightly. This is because the other one saves a little bit by using the same model for low and lowest.

Since looking at bare simplistic tree trunks is a bit boring, here are the three complete trees I made from it. Each is still only 1 LI.

Edit: I didn't notice until now that the two tree trunks have different physics weights too. That has nothing to do with this test. It's just that I didn't bother to change the physics for the one with collapsed lowest model since it's not something worth keeping. The other one has prim physics with more details and lower weight.

Edited October 3, 2022 by ChinRey

[Rya Nitely]

Hi ChinRey, thank you for sharing your tests.

My plants are usually way above 82 triangles, and a very low poly item may give your results. It doesn't work for more highly detailed items such as Reid's flowering plants, for example.

I have performed 1000s of tests while creating. There is nothing I haven't tried, which of course includes adding more triangles in the lowest model.

I set the physics shape to a triangle to keep LI down (my plants are phantom).

I truly wish that a decent model can be produced for lowest LOD and also keep LI low, consistently.

I have often been tempted to use the "impostor" or the 'picture on a triangle' method, but I sell full perm items and people modify it. That imposter triangle texture will always cause issues because the vast majority of my customers don't know how to use it, and I don't want to complicate things for them.

I have spent frustrating long hours, days and weeks to achieve good LODs at all levels, and I work constantly, sometimes all through the night, often just to throw out my work because it didn't produce the results I wanted to keep LI down.

So, there wouldn't be many technical advisors with more experience than I have.

I don't underestimate the efforts of other creators/sellers. I trust that they too have enough respect for their customers' satisfaction. I trust that they also care about the quality of their items. Therefore, like me, they would have tested and tested, and in the end most of us leave the lowest LI at 1 to 3 triangles. I create my own to make sure it is invisible.

 

 

Edited October 4, 2022 by Rya Nitely

[ChinRey]

6 hours ago, Rya Nitely said:

My plants are usually way above 82 triangles, and a very low poly item may give your results. It doesn't work for more highly detailed items such as Reid's flowering plants, for example.

Yes, you have a point there. Higher poly feature plants wouldn't benefit from a dozen extra tris in the lowest LOD model anyway. Fortunately god LOD isn't nearly as important for flowers as it is for trees. A tree needs to be visible from far away, smaller plants don't.

Then again, feature items like your lovely flowers shouldn't really need to have their LI cut down since you can't really use masses of them in a sim anyway. Trees like the one in my pictures are meant to be used in large quantities, hundreds and even thousands across a sim. That's when land impact becomes a significant factor. LI shouldn't matter for the kind of sparse scenes we usually see in SL. Even a homestead sim has 5,000 prims. That shold be more than enough even without having to resort to LOD butchery and other questionable solutions. A full sim has 25,000. Take a look at Bellisseria. Yes, I know I've been quite evrbal about how unimpressed I am with the technical quality of Mole Mesh but that illustrates my point here: The Moles are spending prims like a drunken sailor but they still never run out.

Unfortunately there's a bit of prim count hysteria in SL and since you're a commercial content creator you have to take that into account. The customer is always right after all. I don't make any money worth mentioning from SL so I don't have to worry about that. When I make feature items, I optimize for performance and let them have the LI they need.

[Rya Nitely]

2 hours ago, ChinRey said:

Unfortunately there's a bit of prim count hysteria in SL and since you're a commercial content creator you have to take that into account. The customer is always right after all.

There was a time when 8 prims was normal and acceptable for a decent flexi-prim plant. Now everyone wants 1 or 2 LIs.

Recently, a customer showed me a very detailed beautiful flowering bush sold by another commercial creator, and the only reason she wasn't buying it was because it was 8 LI. She wanted to know if I could do something similar for less, and I told her no.

But that is the market.