Blender to SL Scale/ Blender LoD view distance

[Syle Devin]

So i've been messing around with uploading meshes to make sure my current build will upload properly. Am I correct to see that 1 unit in blender is the same as 1 unit in second life?

Also is there anyway anyone could explain the LoD of a mesh. I uploaded a cube straight from blender in second life and it has bad LoD. I upload that same cube with another object, smaller but with a lot more vertices, and it has an almost infinite view distnace. Keep in mind the second cube did not have any size changes or any more vertices. I only added an object so the mesh contained 2 objects instead of just the cube. Can anyone explain that to me? I can't make any sense of it and it is very important for me to know so I can make sure my build imports as best it can.

 

Thank you

[Coby Foden]

I use metric units in Blender (version 2.61).

So, for example, if make a cube 1 m x 1 m x 1 m in Blender, export it to collada file, import it to Second Life, the cube will be 1 m x 1 m x 1 m in Second Life.

[Gaia Clary]

1 Blender Unit is 1 Meter in SL (if you use Blender 2.5 or newer) BTW the metric setting itself does not change the scaling, only how the sizes are displayed. (However there is an extra scale parameter in the scene settings which is set to 1.0 by default)

regarding the LOD behaviour: Did you use the automatic calculated LOD ? Then it could be (just a guess) that in the secnd case the calculator did do an LOD reduction only in the smaller part of your mesh, keeping the bigger faces (of the first cube) intact.

But its hard to tell what is going on in your case. Maybe you could post the blend file somewhere or at least provide a screen shot of your model ?

[Kwakkelde Kwak]

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Syle Devin wrote:

 

Also is there anyway anyone could explain the LoD of a mesh. I uploaded a cube straight from blender in second life and it has bad LoD. I upload that same cube with another object, smaller but with a lot more vertices, and it has an almost infinite view distnace.

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I'm guessing your new object is one single object. The second Life uploader doesn't recognise the two objects as seperate. So if you add another shape to your object, especially one with more geometry, chances are the reduction on the generated LoDs for the cube part are less than on the cube alone. I didn't do any testing on it, but I would think that besides the size of individual triangles, the angles between them are a factor in auto LoD reduction. So a sphere which has angles close to 180 degrees will reduce before a cube with 90 degree angles.

As I said, I'm guessing your new object is one single object, so the cube within that object might be just as big as the seperate cube, but the overall size of the object is bigger, that means the LoD will change at a larger distance. It also means the landimpact will be higher. There's a lot to gain or lose because of this and it pays off to play around with  complete meshes opposed to linksets.

[Syle Devin]

Yes, it makes sense that the overall size being bigger would affect the cube. what I don't understand, if a mesh is still one object, why seperate parts of one mesh can have different LoD distances. As the second cube that had better LoD view distance was combined with another object that had horrible LoD even though it was the same single mesh.

[Justyn Blackburn]

Hi i have the same problem with my rigged mesh avatars. When I scroll a bit away from my Mesh Avatar then i see the seams of the polygons the mesh has. I tried 6 polygons Avatar and one polygon Avatar, which all polygroups where merged to one! I didnt help, when i scrolled away with the camera, then the Avatar is full of seams.

Seams are just shown when i put textures on the avatar. So i guess maybe the maps are not right scaled  in Blender?

here is a picture

This Bunny HAD several Polygon groups, which are all merged down to one Polygon ( one single Mesh Avatar)

Although seams are showing when scrolling away

 

[Gaia Clary]

If you make your textures with blender, then you may try to increase the seem margin (in the bake options of the render properties panel). The margin is set to 2 by default. I found that a value of 4-6 is somewhat better suited for our purposes.

If you make your textures with another program, i guess the "margin" function should be available there too. If nothing helps then you always can try to add the margins by hand.

[Justyn Blackburn]

Thank you very much Gaia. Im gonna try this out.

Im really a fan of you and your Blog it helped me so much. You can say you teached me blender haha

 

Yes it was Margin now the seams are gone thank you :matte-motes-big-grin:

[Syle Devin]

I take it  the reason seems appear are a little different than the reasons LoD distances might be extremely low or not?

[Kwakkelde Kwak]

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Syle Devin wrote:

what I don't understand, if a mesh is still one object, why seperate parts of one mesh can have different LoD distances.

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They don't. It might appear this way if one piece is more affected by the autoLoD generator than the other, but the switch distance is the same for the entire object. If you have a linkset, this is not the case. My best (sometimes timeconsuming) advice is you always build your own LoD models so you have full control over the behaviour.

[Justyn Blackburn]

yes that bothers me too. I think you have to load up the mesh model with all high instead of  medium Level and low Level  just make lowest Level to 0 and set physics to this lowest Level. Then you dont have much upload costs.

Physics as i learned has something to do when you set the mesh to physical then it has to colide with the ground and objects and so on. If its not needed i dont use physics option! And have Mesh with  High Quality and i pay 12 lindens upload costs with often 0,2 physics only. Maybe im wrong but maybe someone knows better?

[Kwakkelde Kwak]

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Justyn Blackburn wrote:

yes that bothers me too. I think you have to load up the mesh model with all high instead of  medium Level and low Level  just make lowest Level to 0 and set physics to this lowest Level. Then you dont have much upload costs.

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Yes, but depending on your model it might go invisible from a distance or look odd.

 

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Physics as i learned has something to do when you set the mesh to physical then it has to colide with the ground and objects and so on. If its not needed i dont use physics option! And have Mesh with  High Quality and i pay 12 lindens upload costs with often 0,2 physics only. Maybe im wrong but maybe someone knows better?

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The physical shape is also important for other objects. It determines how avatars will walk into it. So it's a must for walls and floors and preferred for all other non worn objects. Just make sure it is very basic. A wall can be 2 or 4 triangles, a floor can often be 2. Most objects will behave just fine with a box as physical shape, some won't though.

 

 

[Syle Devin]

Ah this is all good to know. I didn't realize that there was an auto LoD generator, though how else would it be set if not automatically. Though how can I go about setting my own up  so atleast nothing disapears immediately?

Are there any good tutorials for setting LoD and physical shape for sl mesh or can I just search google with good results? Wish I could say I know how but I only know blender and have never needed to do anything of this before when making a model. So thanks to anyone who has responded, this has really been informative. Wish LL would make all this information known when you have to take that "test" to upload mesh. Though I may have just not seen that information.

[Justyn Blackburn]

Sure it affects it, but when you you do the first three LOD to set all high and the last very low level on 0. and go to category Physics and choose very low level then you save upload costs caz you leave the mesh non physical.

I made this with my rigged avatars and i dont have LOD Problems. And it didnt affect my mesh avatar in movement or any kind of way looking different as i would do it in another way.

 

The thing is that it has just 0,5 until 2 prims, when physics is set to 0 and it though has over 16 000 Vertices and 6000 Triangles and it has very low server lag like a half sculpty. When i do the lowest LOD level to high like 16 000 Vertices and 6000 and put on the physics on that, then this item surely causing alot of lag.

 

[Kwakkelde Kwak]

Setting the 3 first LoD models the same is not good either lag-wise or appearance wise in just about all cases. It either means there is too much geometry in the lower LoDs or too little in the higher LoDs. Best thing to do is make your own LoD models.

Setting the vertice count to as low as possible can't result in 0 vertices and faces, since all materials are represented in at least one face. This means you physical model based on that will have some geometry aswell.

I understand people don't want to build four models for looks and one for physics. It really costs a lot of time. The upload costs I wouldn't worry about, last time I looked a dollar was worth 260 lindens or so.

[Kwakkelde Kwak]

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Syle Devin wrote:

Ah this is all good to know. I didn't realize that there was an auto LoD generator, though how else would it be set if not automatically. Though how can I go about setting my own up  so atleast nothing disapears immediately?

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You can build 3 simplified models of your highest LoD. Then where the uploader says "Generate", change to "Load from file". In the screenshots in the post under yours you can see where that is. Make sure all your models have the exact same material or your mesh won't upload.

[Justyn Blackburn]

I dont think its lag-wise to set all three LOD´s to high when you feel you have an LOD Issue. I think the prim count and the server count is giving me right. My experience is that when i do that and the last is to 0 i have no problems and the land impact is like nothing. As i saw,  there are only three LOD Levels with Sculpties so i think the fourth maybe could also be the one for Physics, when you think of doing rigged avatars.

Once i made a shop in blender and i notices i couldnt go in so i thought it was the physics but it wasnt. You can set this up in the edit options.

The problem is when LOD is changing many Creators feels just bad about it, when they see a lower LOD, LOD means lower Visible Vertices and Triangles, just the whole Creation suffers. It makes the customer feels like that there is something not ok.

Its no problem to create four LOD levels of a mesh but that is not solving any issue caz the meshes of the lower levels will still be lower than the first higher LOD.

Sure LOD is made for view distance, that is giving more space and air for the everybody RAM and Graphic Card and LOD is in every other game.

So dont let us forget there is also and option  under Debugging ---> RenderVolumeLodFactor

Im really intend to learn more about this.

 

[leliel Mirihi]

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Justyn Blackburn wrote:

I dont think its lag-wise to set all three LOD´s to high when you feel you have an LOD Issue. 

[...]

Sure LOD is made for view distance, that is giving more space and air for the everybody RAM and Graphic Card and LOD is in every other game.

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Geometry LOD is for lowering the load on the rasterizer and fragment shaders, it has nothing to do with ram. Depending on the object what you're doing can have a massive impact on performance.

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I think the prim count and the server count is giving me right. My experience is that when i do that and the last is to 0 i have no problems and the land impact is like nothing.

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Yeah you don't have any problems with your one object, try filling up a sim with objects like that an comparing it to a sim full of the same objects with proper LOD. You will see a significant difference in frame rate in favor of the properly LOD'd objects.

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The problem is when LOD is changing many Creators feels just bad about it, when they see a lower LOD, LOD means lower Visible Vertices and Triangles, just the whole Creation suffers. It makes the customer feels like that there is something not ok.

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That's because they make bad LOD models.

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Its no problem to create four LOD levels of a mesh but that is not solving any issue caz the meshes of the lower levels will still be lower than the first higher LOD.

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If it's no problem then why aren't you doing it? It is solving something and the lower LODs are suppose to be lower than the high LOD, that's why they're called lower. There's a reason every game uses LOD and it's not because the developers like wasting time making multiple models of everything.

 

[Kwakkelde Kwak]

 A kudo for answering on my behalf:)..I Don't think I would have responded a whole lot different... I just want to add the FIFTH model is for physics, that one has got nothing to do with any of the LoDs (Even though it can be the exact same shape).

[Syle Devin]

So I am slightly confused from the last few posts on the topic. So I understand now that I can upload my own objects for low and medium LoD settings. Is it bad to have them all as the same model? The reason I as is because I already create objects with as low LoD as possible and so there is nothing more to remove. Is it safe to set them all to the highest my model is at? 

Though all I mostly care about, aside from upload costs and lag on behalf of the model, is that setting my own LoD would not have objects disappear immediately like they are. Would it save me from that? I take it then moving away to where medium LoD would usually show up, if I have the same model set for medium as I do high, nothing would change?

[leliel Mirihi]

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Syle Devin wrote:

So I am slightly confused from the last few posts on the topic. So I understand now that I can upload my own objects for low and medium LoD settings. Is it bad to have them all as the same model? The reason I as is because I already create objects with as low LoD as possible and so there is nothing more to remove. Is it safe to set them all to the highest my model is at? 

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That depends on the object. Some things really are so simple that they don't need the high LODs (note I said high LODs, not low LODs).

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Though all I mostly care about, aside from upload costs and lag on behalf of the model, is that setting my own LoD would not have objects disappear immediately like they are. Would it save me from that? I take it then moving away to where medium LoD would usually show up, if I have the same model set for medium as I do high, nothing would change?

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Whether or not an object will look deformed at various LODs is entirely up to you. When building the LOD models think about what parts will be visible at that range versus what won't and only remove what can't be seen or would be too small to notice.

 

 

[Syle Devin]

So I think I understand what you mean about high and low LoD. I am curious what would be considered need for use of High LoD then? Any oppinions on the build in the image, aside from the sl avatar which is only there for scale?

 

Also I didn't realise it but it makes sense to remove parts of the mesh that wouldn't be seen from a certain distance. Such as the inside of the building could easily be removed because you wouldn't see it as soon as the camera is far enough outside of the building. Thanks for that.

[Kwakkelde Kwak]

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Syle Devin wrote:

So I understand now that I can upload my own objects for low and medium LoD settings.

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Yes you can upload 5 models. One for each LoD and one for the physical shape.

 

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Syle Devin wrote:

Is it bad to have them all as the same model? The reason I as is because I already create objects with as low LoD as possible and so there is nothing more to remove. Is it safe to set them all to the highest my model is at? 

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In some cases the model for all LoDs can be the same yes. If your object is very simple, let's say a box, there's nothing to simplify or to enhance between LoDs. If you have a complicated shape though, especially one with lots of curves like a vehicle or avatar or piece of clothing, it would be a bad choice to use the same model. The goal should be LoD changes that aren't visible and as little geometry as possible on all LoDs without compromising the looks.

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Syle Devin wrote:

 

Though all I mostly care about, aside from upload costs and lag on behalf of the model, is that setting my own LoD would not have objects disappear immediately like they are. Would it save me from that? I take it then moving away to where medium LoD would usually show up, if I have the same model set for medium as I do high, nothing would change?

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As I said earlier, I wouldn't worry about upload costs. You should be able to lower them though by using custom LoD models. The less geometry you use on all mdels combined means less lag on your graphics card (represented by "display cost"). This is why the upload costs are lower aswell. The further you are away from your object, the smaller it appears on your screen ofcourse. If you use full detail on the lower LoDs, the geometry will be calculated, but it won't be visible, simply because it's too small. In that case you can use a simplified model. Do this the right way and you won't see a change.

Imagine a cylinder which has 32 faces to make the curve ( a 1x32 faced cylinder) From up close this will look rather smooth. So as you say from a distance it will also look smooth, but... a 1x16 faced cylinder will look just as smooth from a distance, so you better use this for a lower LoD. Depending on size (which determines the LoD change) a cylinder can be as simple as 3, 4 or 5 faces around. It will take some testing ofcourse what the correct amount will be for your specific object.

 

 

[Kwakkelde Kwak]

i missed the last two posts before responding, they were on the next page...anyway...

In blue are the areas you can reduce geomtry for lower LoDs.

I'd like to add you can reduce your model immensly on any LoD by getting rid of all vertices that don't define a shape. All vertices that are either sitting in the middle of a flat plane or ones that are on a straight edge. You can push them together. I gave an example for the left side of the top. all vertices marked by a red circle can be pushed onto the one marked green. You can do the same for a lot of other vertices, the ones on the left edge are all in a straight line, as are the ones to the right of that (all on a vertical line). The result might look a bit confusing at first, because everything will look triangular opposed to square. That just takes some getting used to. In fact you already did it in one area, the one I marked with the blue ellipse.

Only use vertices where your shape bends.

[Drongle McMahon]

One further point to bear in mind - at the size this object is (radius>5.43m), the lowest LOD doesn't enter into the download weight calculation at all. Therefore you can use the same mesh at low and lowest LODs without affecting the weight. You should concentrate on minimising the vertices at the low LOD to get the lowest possible weight, although the medium is important too. I would reduce the curves to 8 segments per circle (ie, just two segments for the 90 degree corners) at the low LOD, have them as they are at the medium, and actually double the number of segments (to 32/circle) at high LOD. Add to that the reductions Kwak described, and you should be fine.

If this is 10x10x10m, radius=8.7m, then the low LOD will appear only at greater than about 150m, for someone using the default low-to-high graphics settings (renderVolumeLODFactor=1.125). The default draw distances (renderFarClip) are 64, 96 and 128m for these settings, which means they will never see the low LOD. Even on ultra settings (renderVolumeLODFactor=2.0, renderFarClip=256), the low LOD will only appear at about 290m, which will, once again, never be seen. However, since people often use higher draw distances, when making the low LOD, think how much detail you need at 190m distance.