Lowering LI

[Trasee Darkwatch]

I've been looking around, trying to find tips on lowering LI. I've watched quite a few videos as well as read several threads on the topic. I'm still trying to find ways to lower LI without sacrificing quality.

I just started with Blender a little more than a month ago and am using it to build homes for a village. My viewer is Firestorm, and I have my LOD set to 2, which is what most people will be set to. I set my draw distance to 256, and cam away from my models to see when it vanishes (if it does). Some of the smaller items will disappear somewhere between 128 and 256m away. My first question would be, would that be considered an acceptible range?

I build my models using prims in SL. Right now I'm limiting myself to the box prims, sometimes with tapering, shearing or slicing. I haven't worked much with rounded models yet. I then link the prims together. Not as one complete unit, but per wall, floor, roof, etc. I then export the linkset as a collada which I bring into Blender.

In Blender, I have created a script to optimize each prim individually. It removes all the extra texture faces, triangles, edges and vertices (uses decimate as well as remove duplicates). That reduces a regular box to 6 sides, 12 triangles, and 8 vertices, as would be expected. I also remove any obscured sides that would not be visible. For exampe, sides that are hidden by other prims, or might be hidden by the floor or ceiling. Once this done, all the objects are joined and I run a remove duplicate to further remove extra vertices.

This is all done to get my High LOD. I use that to create a medium LOD, by removing additional faces and vertices that do not affect the appearance. Depending on the size of the model, I might also make a low LOD, if I can find other faces to remove. Finally, I make a bare minimum physics model.

In SL, I upload at least the High and Medium LODs. If the model is smaller, I might upload a Low LOD. As mentioned previously, I check to see where the model disappears when camming away, and I always make sure it can ast up to 128m. The remaining LOD items I set to 0.

This process worked well when I was first doing it, and got some of the smaller homes down to 10LI, but I was noticing those smaller ones were disappearing from view between 128 and 256m. Even the larger ones were doing fairy well, averaging 40LI. But one house I did, which was roughly the same size as another 40LI build, wound up being 63LI. Because the walls are larger (16m to 32m in width), they are ony using High and Medium LODs, and still remain visible to my maximum draw distance. If I remove the Medium LOD would vanish between 128m and 256m. I know that would reduce the LI, but not sure if that is the best option. What other options do I have for reducing LI? Have I done everything in this case?

[Drongle McMahon]

If you are interested in a detailed description on size vs LOD, see this thread. You have to decide on the appropriate compromise between LI and LOD stability. As you know, it does depend on the viewer setting people use. The default RenderVolumeLODFactor for the official viewer is 1.125 foe everything below Ultra settings. I try to design for that, but but you are probably right tjat most people have it higher.

If your walls are separate boxes, you may be able to make some vertex savings from joining them, but the LOD distance will increase a bit. Dor a wall with a window, four boxes as Prims, you gain a lot by joining and eliminating vertices. There is also a texhnique where you separate the internal and external walls into different meshes. Then the internal ones can be smaller with more agresssive LODs because you don't see them from outside. So they don't need to look good at lower LODs unless the building is big enough that you see them from inside. Be careful though, if they do switch from inside for people with low settings, the effect is very bad. Also, make sure you don't see too much collapsing from outside through the windows. 

ETA: If you want to make them vanish at low(est) LOD, don't rely on the auto LOD. That can make an ugly big triangle. It's also not predictable. Instead, make a low(est) LOD mesh with as little visible surface as you know how to (several tricks have been described in this forum).

 

[Trasee Darkwatch]

The default LOD is 1.125? Wow. I thought the defaut install was LOD 2. That's why I thought to design against that. I'll need to reanalyze my models under that LOD, to see where things start vanishing.

I saw a couple videos that described changing the auto LOD to 0, which is where that idea came from. Never thought to create a minimal one, due to the texture faces being required. I can certainly see the advantage to doing that, though.

I have been joining the objects together as well, to get the additional reduction to the vertices. Dividing the walls into inside and outside is one thing I've done for texture faces (allowing the texture to be different on either side), never thought of dividing it into two separate models, though. I imagine that might make lining them up a little more difficult, especially since one side would be transparent. I'm starting work on a new house, so I'm certainly going to try that approach as well.

As for the link you sent. I think I'll need to read that over a few times. I get the concept at the high level. Just need to read it over a bit more to get more understanding.

[Drongle McMahon]

That's the LL viewer default. I think third party viewers have it higher. It's more or less essential to have at least 2 to avoid horrible collapsing sculpties. So you assumption of 2 isn't that bad unless you want to cover all possibilities.

[ChinRey]

I recommend you build for LOD setting 1. Usually there isn't that much LI to save by sacrificing LOD anyway - not compared by all the other less destructive and more effective methods.

Seems to me you've figured out the most basic rule already: keep the details you need for each and every model, nothing more and nothing less.

Next step should be to balance the weights. You do that mainly by splitting a build into separate meshes. As a general rule, splitting a large mesh into several smaller ones will recuce download LI and increase server LI.

After that ... oh there are so many tricks we can use. Maybe learn one at a time.

[Drake1 Nightfire]

Are your items on the MP at all? I cant seem to find you listed there. I am very interested in a low LI mesh home...

[Trasee Darkwatch]

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ChinRey wrote:

I recommend you build for LOD setting 1. Usually there isn't that much LI to save by sacrificing LOD anyway - not compared by all the other less destructive and more effective methods.

 

Seems to me you've figured out the most basic rule already: keep the details you need for each and every model, nothing more and nothing less.

Next step should be to balance the weights. You do that mainly by splitting a build into separate meshes. As a general rule, splitting a large mesh into several smaller ones will recuce download LI and increase server LI.

After that ... oh there are so many tricks we can use. Maybe learn one at a time.

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I have been splitting things into multiple meshes. Each wall is its own mesh, for example. I certainly have seen the benefit of that. I generally don't split down a single wall, except in the case of a second story. This has generay allowed me to avoid using the Low LOD unless it is a small wall. Designing for an LOD of 1 could change that, though.

Learning those tricks is exactly why I started this thread.

[Trasee Darkwatch]

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Drake1 Nightfire wrote:

Are your items on the MP at all? I cant seem to find you listed there. I am very interested in a low LI mesh home...

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No, I'm not on the MP yet. Since I just started doing this about a month ago, I have been more focused on the building and learning as opposed to the selling. That will be the ultimate goal of this endeavour, though. Feel free to contact me inworld if you'd like to see the homes. I'm generally online between 6pm and 10pm SLT during the week, and do get offline messages in email.

 

[Jenni Darkwatch]

Personally, I use one of the methods described by Drongle: I split inside and outside into separate meshes. The outside I keep as a rule smaller than 30m in any dimension, but I make the effort to build all LODs for it. Inside I go nuts with details but only build the high and maybe medium detail. Within rooms I do the same thing, often building the rooms separately.

Btw, 30LI for a home isn't bad at all. Our beach fort I think has something like that, and it has no insides

As far as LI switching distance... if it at all matters you can always go ahead and create a distance impostor. Just one surface with the image of the outside wall instead of the actual geometry.

Considering that I rarely have DD higher than 128m, anything disappearing at that distance is really not an issue for me I prefer to have shadows and everything rather than see a mile out and have corresponding long load times/bandwidth use.

For reference, my LOD is set to 2 and plenty of things turn crappy at much, much lower distances. Sculpts tend to turn ugly quickly. Some mesh also does, depending on creator.

[Trasee Darkwatch]

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Jenni Darkwatch wrote:

Personally, I use one of the methods described by Drongle: I split inside and outside into separate meshes. The outside I keep as a rule smaller than 30m in any dimension, but I make the effort to build all LODs for it. Inside I go nuts with details but only build the high and maybe medium detail. Within rooms I do the same thing, often building the rooms separately.

Btw, 30LI for a home isn't bad at all. Our beach fort I think has something like that, and it has no insides

As far as LI switching distance... if it at all matters you can always go ahead and create a distance impostor. Just one surface with the image of the outside wall instead of the actual geometry.

Considering that I rarely have DD higher than 128m, anything disappearing at that distance is really not an issue for me

I prefer to have shadows and everything rather than see a mile out and have corresponding long load times/bandwidth use.

For reference, my LOD is set to 2 and plenty of things turn crappy at much, much lower distances. Sculpts tend to turn ugly quickly. Some mesh also does, depending on creator.

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30LI would be my target average LI for some of the larger homes. I've been accepting the ones that got up to 40, due to the way they were being designed, although using the inside/outside mesh idea, I can probably lower that even more. The one that became 63, though, was a litte steeper than I had desired for the house.

Most likely, I won't be exceeding 30m (or possibly 32m) in most cases. I don't think I'll be designing many homes for parcels larger than 32x32. That is mainly because the village I'm building doesn't have any parcels larger than that. Who knows what I'll do after I finish the village, but keeping with that maximum sounds like a good idea.

Thanks for the comment about the DD as well. I was wondering about that myself. Since I switched my LOD to 2 (previously was at 4) I have noticed how badly a lot of mesh items deteriorated at much shorter distances. Kind of made me cringe with some of them. It is why I thought "vanishing" after 128m might have been ok as well.

Question about the imposter, though. The way I'm currenty designing my homes are to use separate texture faces. I do plan on selling them later, and want them to have modify permissions, so the walls can be "repainted." Is something ike this possible with an imposter? I noticed that you have to have all texture faces in every LOD, so, how would you account for that?

[Jenni Darkwatch]

You'll have to have a separate texture face for the impostor texture, yes. If you do not have a spare texture for that you can actually cheat by using a separate mesh for that, but inverting the high/med/low/very low order... i.e.: For the high LOD use one or two triangles with a blank surface (which can be part of the impostor texture, just UV it to only display the blank parts). For whichever LOD you need to switch to impostor, i.e. low/very low, use the mesh you made that has just a picture of your home. As an advantage to that approach you can make it a box and show the proper view from each side + roof, without blowing LI through the roof.

However... that scheme breaks if you do indeed expect people retexturing the final product. It works ok otherwise. I've mostly used that method for plants and a few obscenely detailed parts like wrought-iron railings and such, and since I never sell my work recoloring wasn't a problem

[ChinRey]

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Trasee Darkwatch wrote:

30LI would be my target average LI for some of the larger homes. I've been accepting the ones that got up to 40, due to the way they were being designed, although using the inside/outside mesh idea, I can probably lower that even more. The one that became 63, though, was a litte steeper than I had desired for the house.

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It's hard to come up with an absolute definition of what low LI means for a house - they differ so much in size and design. But maybe this is a useful measuring stick:

 

The "Meadowbrook Skylight" house is one of the most popular - possibly the most popular - Linden Home and fairly typical of SL houses made at the beginning of the Sculpt Age - a bit bland but not bad design, quite practical and the perfect size for a 512 m2 plot if you don't care about the neighbourhood (and a 1024 m2 if you do). As it is, it has a land impact of 80. But since that house was designed, LL has introduced larger prims and convex hulls and builders have learned how to use sculpts more efficiently. Also, keep in mind that LL chose to make it themselves rather than hire an experienced builder. It is surprisingly well built but even so, there are a few building tricks they don't know.

An experienced prim and sculpt builder today could easily make a similar house at around 30 LI - that is without using a single mesh and, of course, with no LOD issues whatsoever.

If you want to make a mesh house in that size and style, and you want to market it as "low LI", you have to do significantly better than that -  certainly no more than 20 LI (with no serious LOD issues) - and even that may be a bit too high.

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Edit:

I know I shouldn't brag here but I've put together a small exhibition of some of my own low and lowish LI houses at:

http://maps.secondlife.com/secondlife/Coniston/128/128/3000

Haven't got time to make a proper exhibition right now though - I just rezzed a sky platform and scattered the houses around on it. LI varies from 2 to 14 (plus a 1 LI shack I added just for fun). Some of the buildings are examples of modular house system (which tend to icnrease LI slightly), others are as efficient as it's possible to make houses in SL today.

[Trasee Darkwatch]

Yeah, I know LI is very subjective, due to size and design. That's why I said 30LI is my target LI for larger homes, knowing that some might be higher. I have a very small, one-room, home that fits on a 512m plot that is only 10LI, and a large, two story, home that fits on a 1024m plot that is 40LI. I'm not really looking for hard-and-fast numbers, but trying to make them as low as possible still keeping the higher quality.

I really apppreciate everyone's feedback here. It has given me actual things I can do to improve upon my existing designs as well as continuing the work on my village.

Anyone is welcome to come to see the village as well. Obviousy, it is still under construction, but several homes have been completed. All buildings are mesh, unless it still has the default plywood texture (meaning it is being built). It is just over 1/2 a sim and maybe 1/3 of the way complete.

http://maps.secondlife.com/secondlife/Glaurung/122/50/32

[ChinRey]

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Trasee Darkwatch wrote:

Yeah, I know LI is very subjective, due to size and design. That's why I said 30LI is my target LI for larger homes, knowing that some might be higher. I have a very small, one-room, home that fits on a 512m plot that is only 10LI

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That 10 LI house is really, really impressive! Yes it's a very simple design for the most part but it's timberframe and that makes it really hard to keep LI down. As for LOD, some of the buildings are a bit on the low side - I suppose they are the early tries. The 10 LI 512 m2 building is really good. In fact it might be a bit too good because in the end this shouldn't be about reducing LI for the sake of reducing LI. With modern buiding techniwques nobody should run out of LI - not unless they're really flamboyant (and your build isn't) or very careless (and you obviously aren't). But LI is one way to measure lag. It's a very incomplete and inexact way but it's still a useful indicator. And lag always matters.

[Trasee Darkwatch]

The homes that are there currently will remain as I work on the new homes, trying to finish off the village. As I go forward in my building process, I'm going to start designing based on a 1 LOD and splitting inside from outside. The default draw distance for both Medium and High appears to be 128m, so as long as everything stays in place at that distance, it shouldn't be an issue. If it lasts to 256m (Ultra) then that's a bonus.

Funny thing about the 10LI house is that was my first real attempt. I had some earlier attempts in another house (no longer in world) that was where I did a good chunk of learning. There are some things in the design, though, that I don't like. It isn't an issue with how it looks, or the LI, it just made it harder for me to put the parts together and line them up accordingy.

[Pamela Galli]

I took a look at your houses -- nice job . :-)  So are you building inworld, then exporting as mesh to Blender?

 

I am updating my houses to part mesh now, with good LI results.  I just finished the house below -- the house came in at 156 LI.  Before (after conversion to convex hull) it was 196.  And before that, when it was prims and sculpts, it was around 300. Plus I was able to add a lot more detail with mesh, tho not as much as with my all-mesh houses. Plus I was able to get the whole house linked as one object, which I could never before do.

I have found the ability to export the build as mesh essential to building this way, part mesh, part prim.

I build mostly for ppl who either haver higher end computers and can afford to have their LOD set around 3, or who do not care how their stuff looks from halfway across a sim, but as it looks to them while they are using it. 

 

 

 

[Trasee Darkwatch]

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Pamela Galli wrote:

I took a look at your houses -- nice job . :-)  So are you building inworld, then exporting as mesh to Blender?

 

 

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Thank you.

Yes, I'm working inworld first and exporting the various linksets as a collada, which I then bring into Blender. I created a script that basically runs decimate, removes dupicates, and removes the texture faces for each prim that I run it on. The script isn't perfect, and it doesn't work on all prims, so I still have to do a lot of manual cleanup to get the vertice and triangle count down, but it does save a lot of time.

Your home is very nice too. That is a good drop in the LI count.

[Chic Aeon]

Hi there -- Nice houses.

 

My only comments are that you are obviously paying attention and that is SO GOOD .

I always have my LOD set at 4 but I do also test at 2 which is the default for Firestorm -- currently with 75% of the viewer market -- so the majority of SL folks.

Deciding who to build for is a personal thing. I typically try and split the difference between viewability and land impact. As you add more detailing and shapes to your builds the LI will of course go up. The uploader LOVES cubes *wink* but not so much complex items.  So as you work on complexity and shapes I would advise not being too tied to a number (even if just in your head).

Personally, for a house, if I can see it half way across the sim I am pretty happy. There are occasions when I want longer distance viewing but not too often. For personal homes (not malls) people are on smallish lots anyway and as someone who has land on mainland there are many times I would just as soon NOT see the neighbors *wink*.

My only comment on viewing your houses on LOD2 (on LOD 4 of course there were no issues) is that they break apart for me a bit at a time. So rather than the whole house disappearing there was sort of a "pealing away down to the skeleton" kind of feel to the disappearing which didn't work well for my sensibilities . And it was a sensibilities issues - LOL.

Enjoy the learning journey. It pretty much doesn't end with Blender.

 

 

[Trasee Darkwatch]

Yeah, at LOD 2, if you go beyond 128m, some of the houses do start coming apart. It is even more noticable on LOD 1 (as ChinRey pointed out to me). Two of the houses are currently under construction, using older walls that don't have as good of an LOD, and is mainy used to help me design my homes (and to export as part of the linkset). As I bring those into Blender, I'm going to start working on them using the tips presented here. My first task is making the doors stand up better on the LOD, as those tend to be the first to disappear, due to their smaller size.