LOD vs Draw Distance

[Syle Devin]

Well today I came across the fact that LOD distances are also connected with your draw distance settings. As a creator who wants to make objects that work well for others is this something I should worry about?I can't control what others set their draw distance to but maybe I can inform people of the draw distance vs LOD distance. Any advice or thoughts on the subject?

[Cerise Sorbet]

It's a little more complicated than that. Higher graphics settings make a difference too. There is an LoD setting in the advanced part of the graphics settings, and that in turn ties to the RenderVolumeLoD debug setting.

A good plan is to crank down your graphics to fairly low (most SL users aren't running on gaming hardware) and make sure you stuff can look reasonable with RenderVolumeLoD at 1 or so. If you rely on people only seeing the highest LoD, there is going to be disappointment, those lower detail models do matter.

 

[Syle Devin]

That's a good idea, working in low graphic settings. I noticed even in the lowest setting "object mesh detail" stays at mid keeping the LOD distances quite workable; it never changes to low and only changes to high on ultra settings. But the only reason I found out about this is because I accidently had that option set to low instead of mid and I could barely pan away without seeing the lowest LOD distance, which worried me that something had changed with mesh upload. I guess I'm just thinking if I may want to include something in the way of trouble shooting or what

[Drongle McMahon]

Draw distance per se doesn't affect the LOD switch distances. Both parameters are affected by the graphics quality, but they are otherwise independent. The quality setting and the object detail slider change the debug setting RenderVolumeLODFactor (rvlf) which does control the LOD switch distance directly. By default it is 1.125 except for Ultra graphics where it is 2.0. Many people set rvlf to 4.0, to mitigate the effects of ugly sculpty LODs, but the safe thing to do is to assume that most viewers are using 1.125. You can change it using the Advanced->Show debug settings menu item. You can a;so change the draw distance that way (called RenderFarClip if I remember correctly).

The switch distances for an object are proportional to the object "radius", which is the half-diagonal of the bounding box. It can be calculatede as r = sqrt(x*x + y*y + z*z)/2, where x, y and z are the dimensions of the object in meters. The first switch, high to medium LOD, is at: rvlf * r/0.24; the next at 4 times that distance, and the last at 8 times. For objects with major dimensions of 1m, at rvlf=1.125, these are about 4, 16 and 32 m for a cube, 3.3, 13 and 27 for a thin plate, and 2.5, 9 and 19 for a narrow rod. Just multiply these by the scale factor for larger or smaller objects. Multiply bu rvlf/1.125 for different settings of that parameter.

In fact there are other small adjustments that affect these distances, but the above is still a reasonable estimate. There is also a delaying effect that causes the distances to appear different depending on whether the camera is approaching or receding from the object.

[Chic Aeon]

Drongle of course gave you all the info you will ever need *wink*.

I am just chiming in here with what I see. Mesh creators typically decide which "market" they want to build for. Most of the top designers (the names you know in the home and garden industry) do NOT go for the lowest LOD setting. THEIR customers are the folks that are older and know to reset their LODs to 4 (very easy in Firestorm on the Quick Preferences panel). They seem to be doing quite well with this choice. (Yes, there is a big, BIG smile there).

So realistically you need to decide just who you are building for. If you make items that can be seen well from a distance at the lowest LOD settings, then you end up with much higher land impact cost. SO, it is a trade off and you need to figure out who your customer base is. If you are building for the new folks, then I would go with the low LODs. If it is the oldtimers who know there way around a viewer, then I wouldn't worry about it.

There are markets for each type of build and your personal ideals of course fit into the picture. By all mean TEST on the Aditi grid before you decide which way you want to go.

I have my LOD at 4 and if I can see a house half way across a sim I call it good. I also have very low land impact numbers which are important to me on a personal level. Others build for LOD2.  Since scuplty folks inserted those "making sculpties look better" cards for YEARS we have to assume that a lot of folks know the drill.

Just my two cents. I am no longer building on this grid. Happily I don't have to worry about LODs any longer (yep, smilin' big time here).

Good luck on your journey.

[arton Rotaru]

There is a reason why the default RVLODF is at 1.125 or 2.0 for Ultra settings. And that's called performance. It also means really nothing how long people are in SL. There are still plenty of oldbies who are running old computers.You are correct that the advise to set the RVLODF to 4.0, or something higher even, relates to the "poor" LOD behavior of sculpted prims. In fact, if sculpted prims had been used for what they were intended, namely organic geometry, the LODs would work quite well, even with the default RVLODF.

Though, people made all kind of objects out of them (including me), and in a way that the LOD behavior just did not work.

Luckily we have Mesh now, and don't have to do these crap sculpts anymore. And actually there is no excuse these days, to not provide properly made LOD meshes, all the way down to the lowest. The quality of these LOD's may vary with what you want to achieve, really low land impact, or great view from all distance for any kind of viewer settings, or a compromise in between.

But just skipping these steps, and tell people they should mess up there viewer settings, just that they can see an object properly, isn't really an advise I would give any SL Resident, may it an oldbie, or newbie.

A few weeks ago I looked at a super detailed car. It had 220.000 triangles in High LODs, and a land impact of just 22! Guess what, that thing transformed into a piece a triangle garbage just with the cam 10 meter away, with default RVLODF settings.
I certainly don't want to mess up my settings to just see such highpoly crap correctly, just because some people are to lazy to make good game assets, or they just want to cheat the system, by skipping LOD meshes, and advertise their stuff with ultra low land impacts, and these amazing amount of detail.

[Drongle McMahon]

"...the folks that are older and know to reset their LODs to 4..."

As well as the performance issue Arton mentions, there is the question of what these super-users are doing with their content. If it's in their private space, OK, but if it's somewhere they care about enjoyment by other users, then they may not be getting what they thought. Unless they inspect at lower settings, they may be surprised to learn that their visitors are seeing a degraded environment. It is one of the best features of mesh that you can make good lowest LOD models and stll get very low LI, using the billdoard method for example. As you say, it depends on how discerning your customers are. I would generally not want to buy something until I had inspected it's lower LOD appearance. Doing good low LODs does cost effort, but not necessarily LI. Perhaps the best plan is to offer different versions.

[Syle Devin]

I personally don't find creating lower LOD to be that time consuming as most of the time I can usually get away with colapsing vertices. Though I never create a lowest LOD, I set it to 0, because it effects the land impact so much.

What had me worried with what I ame across was how soon it caused the lowest LOD to show up. Luckily, if I don't mess with the graphic settings accidently like I did, even the lowest graphics settings causes the lowest LOD to show up pretty far away. 

I think may have been a bit worried about that to. With different graphics settings can I still get away with having nothing set for the lowest LOD. 

[Drongle McMahon]

"can I still get away with having nothing set for the lowest LOD."

Well, taking the 1m cube, at 32m, beyond which the lowest LOD gets seen at rvlf=1.125, , it's 14 pixels square on my monitor. The way the calculation works, it will be at that pixel size whatever the size of the object. That's quite visible. So I would rather use a cube. At least that looks more or less the same from all directions, while a single triangle (you can't actually get zero) will look different depending on the angle, invisible from half of them. Of course it all sepends on what else is around, what the texture is etc. These affect how visible it will be. So there isn't a recipe that will work for all environments.

[Pamela Galli]

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Chic Aeon wrote:

 

I am just chiming in here with what I see. Mesh creators typically decide which "market" they want to build for. Most of the top designers (the names you know in the home and garden industry) do NOT go for the lowest LOD setting. THEIR customers are the folks that are older and know to reset their LODs to 4 (very easy in Firestorm on the Quick Preferences panel). They seem to be doing quite well with this choice. (Yes, there is a big, BIG smile there).

So realistically you need to decide just who you are building for. If you make items that can be seen well from a distance at the lowest LOD settings, then you end up with much higher land impact cost. SO, it is a trade off and you need to figure out who your customer base is. If you are building for the new folks, then I would go with the low LODs. If it is the oldtimers who know there way around a viewer, then I wouldn't worry about it.

 

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This is true.  My target market 1) care about LI and 2) know about raising their LOD levels -- I build at level 3.  I have all of my mesh on display inworld, and marketplace listings are linked to inworld locations, so there should be no surprises if someone keeps their LOD at default. Most of my mesh is furniture seen mostly indoors so no one is going to be doing much viewing at great distances.  With my houses, the meshes are large enough they look fine at a distance -- except for windows, for which I often have to make low LODs. 

 

 

 

 

 

[ChinRey]

Not sure if I should have created a new topic rather than reopen on that's over a year old but...

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Drongle McMahon wrote:

The switch distances for an object are proportional to the object "radius", which is the half-diagonal of the bounding box. It can be calculatede as r = sqrt(x*x + y*y + z*z)/2, where x, y and z are the dimensions of the object in meters.

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That formula is not correct at the moment. Take a look at this picture:

The two windows here are absolutely identical except for one thing: The one to the left was rotated 90 degrees before uploading (so that the long side was along the x rather than z axis) and then rotated back afterwards. It seems the size along the local z axis is completley ignored so the actual formula is:

r = sqrt(x*x + y*y)/2

This is almost certainly a bug and I have posted a JIRA about it. But it's a good idea for everybody to be aware of it until it's been fixed.

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Chic Aeon wrote:

So realistically you need to decide just who you are building for. If you make items that can be seen well from a distance at the lowest LOD settings, then you end up with much higher land impact cost.

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 Since I'm posting here anyway, I think I'll add a comment to that.

What Chic Aeon wrote was probably true back in March 2013 when she posted her comment. But we've learned a lot about mesh since then and LL may also have tweaked their algorhitms a bit. Today any skilled SL mesh maker has a vast arsenal of LI reduction techniques far more efficient and less destructive than the old LOD sacrifice method.

This is similar to what happened to sculpts. At first all sculpts were low LOD but then builders figured out how to use oversized bounding boxes and strengthened points and today's expert sculpt makers are able to make sculpts that are nearly as LOD resistant as regular prims.

Increasing RVLF comes at a cost. It forces the server to send far more data than necessary (since it affects all objects in the area, not just the low LOD ones) and that adds significant lag, especially on the client side of course but also on the server and network. It may still be necessary to view old sculpts and meshes (and sculpts and meshes made by builders who haven't learned the techniques yet) but generally I think it shoud be avoided whenever possible.

[Chic Aeon]

Hey there --

Just wanted to say yes, things indeed have changed since I wrote that. I always test at LOD 2 as well as the LOD 4 that I have set in the viewer as my default (Firestorm lets you do this with a slider so super easy). I have noted on most things that the differences no longer matter much.

I hadn't put that together really OR remembered how big a difference it was when I first started with mesh, so this was good to read. I have also been on other grids and platforms since I wrote that and I now understand that things can be quite different depending on how the uploader  -- well, uploads! LOL.

So it is easier now and while we still need to test for the folks viewing at LOD 2, it appears not to matter nearly as much. Whether an uploader change or a viewer change (I am betting on number 2 but perhaps both), it is a GOOD thing.  We always of course had the option of making custom LOD models. I remember one of the first videos I watched on mesh was The Kettle Quest which was aimed at getting folks from sculpts to mesh and explaining LOD distance and how to delete loop cuts to simplify your model for the different distances .

It is still that last LOD model that can crank up the land impact -- in many cases anyway.  For most of the items I make the last LOD can be set as low as possible with no issues. You do not need to see a chair all the way across the sim . 

TESTING is always the best plan in my book. 

[ChinRey]

Yes, one of the most important lessons we have learned the past year is to control each and every model in detail and also which models to keep and which to zero out.

To illustrate how far we've got: the window I posted a picture of was made for a house I'm working on at the moment. About 500 m2, quite highy detailed, irregular shape, two floors (but staggered so there are actually five floor levels), a very elaborate (85 prim) staircase...

Back when prims were the only building material available, that house would have required at least 600-700 prims, maybe more.

A year ago, it could have been made with mesh at an LI of ... perhaps 100 or so.

Today ... I already know I can get the LI down well below 30 and I'm hoping for 20. That is with no LOD compromices worth speaking of. Set your graphics prefs to default medium - RVLF 1 and draw distance 128 and it still looks perfectly fine halfway across a sim.