LODs for SL Dummies by SL Dummies (Part 2)

A full set of 4 LODs for an interior fireplace, courtesy of a Dysfunctionality designer.

The topic that really pushed me to start this blog – LODs, and why they’re so crucial for Second Lifers (SL) and SL creators despite being almost totally ignored even by people who have enough skills to know better. The issues creators neglect to research about good game dev practices are part of the major root causes of lag and consumer unhappiness in SL today.

I am not a professional, I honestly never aspire to be. However, I have spent considerable time in recent years trying to do my best to create a good experience for my consumers and the grid as a whole. This includes simple optimizations on LOD and textures. I hope what I have learned can help others, too.

LODs and their band-aid fix of LOD Factor are not the whole picture in terms of optimization and issues, however they are a part of it – and an important part to understand before you can progress to other aspects such as textures.

That said, you can fix these issues, and it will only take a small amount of your time once you understand first how LODs work, and how we arrived to this crisis of triangles.

What are LODs in SL?

LOD stands for Level of Detail, a gaming industry generic term for the way models look at certain sizes, and in SL is one of the most significant parts of the land impact and avatar weight algorithms – for good reason. Linden Lab has provided us tools in the uploader to help with this, and encourage better modelling habits.

At its very essence, Level of Detail (LOD) in SL describes which model is being displayed given a designated distance measured from your camera.

For us as SL creators, when we talk about them – LODs represent the 4 numbers shown in our mesh upload window for High, Medium, Low, and Lowest in the Level of Detail tab. This is the first tab you see when uploading an item. It shows us the triangles and vertices of our uploaded High LOD, then offers us some autogenerated and “suggested” settings for the Medium, Low, and Lowest. You can see each number is harshly divided from the one above it.

You can also use the pull down tab and choose to “Load from file” or “Use LOD above” instead of generate – we’ll get to this in the next post.

The SL Uploader showing default generated Level of Detail

These numbers form the way our meshes look at certain distances from our camera, not the SL Avatar, due to the way we can zoom our camera around freely unlike games such as Overwatch.

We can preview these models by clicking on the numbers associated with the triangles/vertices of each level in the uploader. It will also give us an idea of what our land impact will be based on combining the 4 models, the physics, and the size information that you input.

Hallelujah! After over half a decade of having to struggle with understanding these distances for each LOD by guessing games, inaccurate ring theories, and general voodoo rituals, Firestorm put in an awesome change to our edit menu.

The “Object LOD Behaviour” section which accurately illustrates not just your current viewer setting for LOD Factor calculated in, but the default LL (1.125) and Firestorm (2.0) settings is an invaluable tool. This shows that for those using the lowest default settings, this set of bricks will go down to the Medium in 8.7 meters distance, which is actually rather short.

Of course, if I was running only LOD Factor 4 settings and never checked other ones – this would never even happen until 30 meters away. This is why it is so important to look at your meshes with default settings, to make sure they look great to everyone. Test at LOD Factor 2!

Brick on medium LOD, not as nice but still obviously recognizable.

On the other hand, if this brick was half the size on default SL it would be only 4.3 meters before it went to that same Medium level! Which is why getting your LODs just right for the size and visibility you expect it to be used at is so crucial. For small items or large items, you’ll have to craft their LODs very differently to balance with land impact. Large items might need you to be dozens of meters away before it visibly degrades.

This is because LOD is calculated based on the size the item is on your screen, hence why the size penalty in land impact is so huge. It is not uncommon for me to need to upload my initial product multiple times to achieve the right balance of detail to land impact, which is why testing on the beta grid with free uploads is very highly suggested.

For many creators starting out, we’ll just use these autogenerated settings by adjusting the uploader options to reach something we’re satisfied with, usually jacking up the Medium to be the maximum and dropping off Lowest to be the minimum of 0 with no regard for the function, size, and use of this item – uploading as is.

Satisfied only by the low land impact, we give it a lookover at our biased LOD Factor 4 settings and set it for sale.

Using some of the basic generated LODs on an old product.

We don’t know better. We’re self-taught, following some tutorials here or there, asking our other creator friends to help us with our troubles at they come, and don’t know any other option. These are just numbers, and you don’t really care what they mean as long as you get the result you want: low land impact, high sales.

Sadly, on upload is the first and last creators ever think about LODs, yet these final stages are when we should be thinking about LODs the most.

LODs impact your customers FPS, loading issues, and everyday gameplay by having to load poorly optimised, high polygon meshes from distances that we couldn’t possibly appreciate their detail. We need to be more considerate. To consider what we are putting out there forever – just look at those mainland sims, stuck in the same state for decades now.

I fear this mesh era we have been creating will be encapsulated and known for its poor LODs and excessive texture use.

The root of our problems, and also the solution.

The ‘bandaid fix’ of ‘just turn up your LOD Factor‘ is one of the largest parts of the perceived lag that many people experience today. There is no reason that consumers need to load fully detailed, thousand-triangle meshes from half a sim away. It’s laziness on our part. Passing on the blame and expecting that we should force others, especially those who can barely use the complex SL Client, to change their own Debug settings so that we can lazily cheat the system is wrong.

We are wrong.
This is a problem we as creators are only compounding, out of lack of knowledge largely. We are also the solution, and it begins with us to take time, care, and consideration as to what we are giving to this world and learning better habits.

Your reward will be items you can stand behind, better land impacts, avatar rendering costs, lower lag, and something people can enjoy for years to come. These skills and understandings will also let your works be usable in other digital grids or games.

3 level of detail models for a recent boulder release. I expected them to be used at large sizes, so they only feature High, Medium, and Low settings. Low is just cubes!

To understand LODs in-depth and the ways to fix them, we have to explore how SL interprets them. In the next post of Part 3 we’ll discuss the major enabler of poor practices: LOD Factor, and my personal history with releasing bad LODs.

Leave a Reply