Second Life Third-Party Dev Meeting 2017 w46

Better LI and ACI

The Lab is working on a better render cost and land impact for performance measuring. The Lindens are sort of working on this as a side project. It’s nobody’s project just yet. Whoever is available for a bit runs over and bangs on it.

This is a complex problem because some video cards do one thing very well and another card does the same thing very poorly. So, with the verity of video cards the Lindens face among SL users, no perfect measure is likely to emerge.

What they are telling us is HD Graphics is not likely to get much consideration. They won’t say HD Graphics specifically. They are being PC and avoiding offending Microsoft.

But, because they not going to give much weight to old machines and cards, especially those with HD Graphics, those system are not likely to be well represented by whatever the new weighting system reports.


However, they are looking at LoD, Level of Detail. For some time LoD has been a topic of debate in SL. It is more or less ignored in clothes. Many designers tell the users to set their viewers LoD to max (4) for best results. Well, that works but circumvents the entire purpose of LoD and lags the world.

LoD is a 3D modeling thing done to save render time. The high-level model with lots of polygons is designed to be seen up close. It is the most detailed model. The next level down is a similar model with fewer polygons and is meant to be seen from farther away. So on to the 4th level with is the fewest polygons meant to be seen from far away.

For a building, the lowest level model might be a rectangle with a picture of the building on it, like 2 polygons. Clothes are complex and 4th level low poly models would likely still have a few dozen to a couple of hundred polys.

As it is now, designers often ignore building a good low-level model and simply use a single polygon to lower the LI and ACI. So, if you have a normal LoD setting to take advantage of the performance gain you see whatever change to a triangle as you move away from it or appear as a triangle until you get close. The effective but lazy-dumb solution is to turn the viewer’s LoD to 4 to make it always use the high polygon model.

The Lindens are trying to find a way to penalize stuff that does not use good LoD modeling, meaning higher LI or ACI. It is not clear they can. But, I won’t bet against them.

The Changes

Changing LI and ACI has lots of impact points. If how LI is calculated changes and increases the LI of existing things, it could force a region to return huge numbers of things. Not what the Lindens want to see happen.

So, if the new calc pushes LI up, the Lindens may raise the max allowed LI for a region so that an existing build is not returned. It makes sense. It is like saying the 70 mph shown in a US speedometers is being changed to 110kmph. The number 110 is bigger than 70 but it is the same speed.

Baking Service

Not much new on this. It is sort of mostly discussed in the Content Creators UG.

Oz does reiterate that the current change from 512×512 textures to 1024×1024 that is soon coming to the main grid is the FIRST STEP in a larger plan to reduce textures in use.

The idea is those mesh bodies will be able to bake like the classic body does.

If you don’t know, the classic body is a; head, upper and lower parts. The upper has a skin, tattoo, underwear, shirt, and jacket layers. The others parts are similar. That is five textures. The baking service was introduced way back to composite the 5 textures, whatever size, into a single 512×512 upper texture. That is what we see on the classic body. This is a huge saving in bandwidth and video ram.

Mesh bodies have no such texture saving feature. Also, they do not have layers. Mesh things have a single layer. So, the layers you see on you mesh body are from a number of duplicate bodies. One layer per copy.

As the Server-Side Baking Service advances the plan is it will eliminate the need for multiple copies to simulate layers. We will get a reduction in polygons and textures. Unfortunately, the SSB does not support materials. Until it does, I am not at all sure I want to use it for my avatar or much of anything else. I’m into materials.

As it looks now SSB with materials is long ways down the road.

Leave a Reply

Your email address will not be published. Required fields are marked *