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Syle Devin
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Re: Quality vs Land Impact.

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Reply to Drongle McMahon - view message

Hmm well I already turned the lowest level into a cube with no bottom but I did not think about others who might have lower graphics than I do. I'll try and see how it is. One other thing though, does anyone know if it is possible to have different textures for each LOD distance? Such as where the original texture map is on the highest quality but on the lowest quality that is only a cube I might have a modified texture map so it still looks like the chair and not a cube of fabric.

Drongle McMahon
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Re: Quality vs Land Impact.

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Yes. It is possible. The requirement is that you need to have the same set of materials used in each LOD*. You can achieve that by having a small hidden triangle in the high LOD mesh to carry the material for the lowest-LOD texture, and also one(or more) in the lowest LOD for unused high LOD texture(s).

*If you study the wiki, you may notice that the stated requirement is that the lower LODs can have a subset of the high LOD meterials, implying that the extra triangles are not needed in the lowest LOD mesh. However, there are some bugs that cause the wrong textures to be applied after LOD switches to higher LODs in some circumstances. To avoid these you need exactly the same set of textures. As far as I am aware, these bugs haven't been fixed, but after the jira accessibility changes, it's difficult to know without constant re-testing.

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Maeve Balfour
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Re: Quality vs Land Impact.

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You can incorporate different textures per LOD mesh, BUT this will require using a separate material per new texture to do so. Keep in mind that a mesh can hold a maximum of EIGHT materials in total - this includes all the LOD meshes.
In theory, one dedicated texture for your maximum detail mesh and subsequent lower LODs, and a separate dedicated texture for the lowest LOD would be sufficient. It's always a good policy to aim for the best possible efficiency, so a lower resolution texture for the lowest LOD mesh would be a good idea, especially since it would only be visible at a longer viewing range (and the pixellation would not be easily discernable).

Each LOD mesh will need to have each material in usage, even if not actually intended for that particular LOD. A good method is to place each of the unused materials per LOD on tiny triangles and hide them from view inside the object. By doing so, each LOD mesh can, if necessary, have its own dedicated texture.

However - the added materials and requirement for hidden triangles will possibly increase your Land Impact calculations slightly. Not by much (if at all), but keep this in mind. The gain in visual quality, though, should be more than worth it.

:matte-motes-smile:

ETA: Argh, beaten by Drongle AGAIN! :matte-motes-wink:

Exploring my creative side inside of SL
Chic Aeon
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Re: Quality vs Land Impact.

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Loved Chosen Fews graphics. My old logics professor would have smiled.

For me, and this subject is VERY important to me -- the primary thing to remember is that no one is going to see the hinges on your door from way across the sim. I spend a lot of time camming out from a distance (camera restraints is where you get that ability - in preferences but I imagine folks here know that) to see how things look.

It is very true that many (maybe a majority since I haven't seen so many of those "how to make your sculpts look better notecards") may have their LOD viewing set at the default which for some viewers is 3. Firestorm now has a very easy way to up that to 4 -- right in the Quick preferences, but lots of folks most likely don't know what LOD means and why they should care.

So whenever possible (and it often is ) I set the LODs for the two highest levels the same. On some items (again visually testing) you can have the LOD at 0 and the object will still hold its shape from beyond sim distance. And honestly, who in the real world could possibly see that well? We know a car is a car not because of the details, but because we perceive it as a car -- often a moving one.

So the hard decisions really come with larger structures that are more costly in the LOD mid and low range. It might be very important to you for your arches to stay crisp. What I have noticed in the RETAIL world though, is that the top mesh designers opt for a middleground. So a house WILL fall apart a bit from way across the sim. But most of the time we see it from a closer distance. I have a tendency when faced with an actually NEED to make that quality vs LI decision (all the tricks to get the LI down have been exhausted) to go for the quality. It is often only 10 percent of the LI cost will get you a much nicer build.


I wrote an article recently on my design blog about mesh and land impact. It might be of interest. Don't be put off by the scantily clad photo -- it really IS an article all about mesh *wink*. Gotta keep the fashion feeds happy. They are not big on techie prose.

While LI will most likely not be important in the art world, if we are talking products -- I think the future belongs to the designers that can make smart mesh and texture well (that let's me out as I am not a great texturer :smileyvery-happy:). When you can live in superb style on a 512 for free by buying beatiful low impact furnishings the need for all those prims kind of fades away.

 

http://chicatphilsplace.blogspot.com/2012/12/into-future.html

 

Flowing around the rocks is a good thing -- just don't drown in the process.
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Kwakkelde Kwak
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Re: Quality vs Land Impact.

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Maeve Balfour wrote:

However - the added materials and requirement for hidden triangles will possibly increase your Land Impact calculations slightly. Not by much (if at all), but keep this in mind.


There are a few more things to take in mind when you use different textures for every LoD.

First is your landimpact, which shouldn't be the first thing to optimise, but often is. If you use a seperate material for every LoD, you will have to add an extra triangle for every unused material in the other LoDs. So if your lowest LoD is a bottomless box which has 20 vertices (if the edges are sharp) and 10 triangles, you'll have to add three triangles with 3 vertices each. This means an extra 9 vertices and 3 faces, quite a lot more. Depending on the size of the object and the numbers of it in a linkset,  this can result in a substantially higher landimpact.

Second is texture use. Although it might not be obvious at first thought, adding a low resolution texture to your lower LoDs will not lower your memory use, it will raise it slightly. Because of mipmapping, SL won't download the full texture if the object is far away, but a sampled/scaled down version. Adding an extra texture will...well add an extra texture to be processed. It doesn't really replace the others.

Third is the ability to modify colour on an object. If you have for example a car which has a shiny material for bumpers, a flat material for paint and a translucent one for the windows on the highest LoD and a small texture for the lower LoDs, changing the colour of the paint won't affect the color on the lower LoD material. Changing the colour on the lower LoD material will change it completely. So your chrome bumpers and glass will change colour with the paint. In such a case it's probably better to share materials between LoD models.

 

 

"The superior man understands what is right; the inferior man understands what will sell."
Confucius

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Kwakkelde Kwak
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Re: Quality vs Land Impact.

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Chic Aeon wrote:
So a house WILL fall apart a bit from way across the sim.

It doesn't have to and it shouldn't. The trick is in making good use of linksets. Maeve has tested a lot with this. I myself have done some. My first "rule" is to break your build into exterior, interior and windows.

The exterior should be very LoD resistant to keep the shape over a distance. A big build will never fall to pieces with just the highest LoD modelled. The rest can be set to 0. (This is with all the default LL settings from low to ultra , a very long draw distance in combination with a low object detail won't work).

The interior can fall apart from a distance any bigger than the biggest indoors distance it will be seen from. This means you can break it into pieces. The entire interior as one mesh results in a LoD switch distance far bigger than needed.

The windows are more or less flat, so you can use imposters at LoD med, low and lowest without it being obvious or even visible at all.

The second thing to do is cutting up/combining pieces. Currently I'm working on a building about 50x30x15 meters. The plan has an I-beam shape. I tried some different setups for the exterior:

- Making the entire exterior out of one piece

- Splitting it in three with the vertical part of the "I" as one piece and left and right each as one piece

- Splitting it in three with the vertical part as one and top and bottom both as one

- Finally I tried it as 5 seperate pieces

The first option results in very resistant LoD behaviour, more than you need. It probably won't fall apart at more than 1024 meters. This is too much for the default settings and results in an unneccecary high LI.

The second option kept the shape of the outer pieces at any default LL setting, but the center broke. Rather than combining the pieces again, I added a medium LoD model.

In the third option all three pieces broke from a big distance. Given the bigger complexity of the outer models, adding a model for medium would have resulted in a high LI. I didn't try this.

The same is the case for the last option, but of course the models broke from a shorter distance.

All in all, if I had fiddled with the medium LoD models to let them keep their shape, the different setups would have looked the same, but the LI would have a factor 3 between them at least. With option 2, I managed to keep the LI for the entire exterior at 15. Uploaded as one single object it would have been 20.

Building_Ext.JPG

I am now fiddling with the windows, looks like clusters of 3x3 for the wings and 2x2 for the ends will result in the lowest LI.

Also notice the geometry for the entire exterior is about the same as half a sculpt for the tris and about three fourths sculpts for the verts. Just to point out how horrible sculpts are.

"The superior man understands what is right; the inferior man understands what will sell."
Confucius

Drongle McMahon
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Re: Quality vs Land Impact.

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The only problem with multiple parts for an exterior is that, from angled views, the parts swtich LOD at different camera locations, so that you can see mixed-LOD views. This can be unpleasant unless due care is taken with the medium LODs to mitigate the effects.

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Chic Aeon
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Re: Quality vs Land Impact.

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:smileyvery-happy:. I actually knew it didn't have to fall apart *wink*. I am a small home gal so I doubt I will need to be tricky, but I do understand the separation of parts as I used that even on my tiny casita and saved a TON of LI points.

I think experimentation and testing is definitely the key. My little house (and it is little ) holds together across a sim and that is good enough for me.

I also think though, philosophically, that it can be easy to get very wrapped up in the quest for perfection. I had an occassion today where I had  to decide whether to upload at 1 or 2 LI  for a fairly complex piece of furniture. In the end I opted for 1.5 which if someone wants can easily be 1 by making it just a tiny bit smaller, or can be much larger and retain the 2. It holds it shape half way across the sim and honestly, it is supposed to be INSIDE the house - LOL. So that's good enough for me. The first two LODs are full.

If you are building a castle, that will be seen "across the land" (mainland that is) then I can see the importance of a really good low LOD, no aurgument here. Many times, though, it really doesn't make much difference.

Flowing around the rocks is a good thing -- just don't drown in the process.
Rahkis Andel
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Re: Quality vs Land Impact.

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This is a life lesson hidden in a second life lesson.

Don't get so caught up in the trees that you become lost in the forest.

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Kwakkelde Kwak
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Re: Quality vs Land Impact.

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Drongle McMahon wrote:

The only problem with multiple parts for an exterior is that, from angled views, the parts swtich LOD at different camera locations, so that you can see mixed-LOD views. This can be unpleasant unless due care is taken with the medium LODs to mitigate the effects.


There is no switching at all, that's the point. The switching happens out of range of any default settings.

You don't want to match the switching, you want to eliminate it altogether, either for real or just how it appears.

"The superior man understands what is right; the inferior man understands what will sell."
Confucius