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CharleeDavidson

What Causes High Land Impact When Importing Mesh?

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Hi All,

I've been learning to mesh in blender and can now create simple mesh objects. I am planning to open a Marketplace store and sell my creations but I have wanted to build up some inventory before I do. So, I just keep practicing by making more things to sell.

I am really confused on how the LI is calculated.

None of my objects are very complex and the highest poly count has been around 2K for a coat rack with an attached bench.

I made my own LODS and assigned faces to parts I thought customers might want to re-texture inworld. There were a total of 3 faces that could be textured. This object is one piece and only has 1 UV Map.

The LI for uploading this was 2 (I created my own physics shape to use)

 

Last night I made a ridiculously simple (or so I thought) photo frame that was basically 2 empty picture frames held together with hinges and had a wire strung across the inside of the frame and 2 floating photos were held onto the wire by clothes pins. It has 1650 polys.

When I uploaded this model to the beta grid today, it had a LI of 32!

This simple photo frame has less polys than the coat rack so I'm confused as to why it was so high.

Does adding more material slots in blender increase LI?


Thanks in advance for any input.

- Charlee

 

 

Coatrack Bench.png

Clothespin Frame.png

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Posted (edited)

I think this is going to be a long thread but to get things started, land impact is based on three "weights":

  • Server weight is how much work the model givs the assets server. For an unscripted single mesh, prim or sculpt it is always 0.5. For a linset it is 0.5 per part in the linkset.
  • Physics weight is how much work the model gives the sim server. It depends on how complex the physics model is (since that's supposed to be the only factor that really matters for the sim server)
  • Download weight is based on how much bandwidth it takes to download the model.

It is only the highest of these three weights that counts as land impact. That means, if you want to reduce the LI, you have to first check which of them is the highest and work on that one. Looking at the pictures I would guess it's the physics weight that is causing problems in this case but I may be wrong.

There is only one way to reduce server weight but a ton of methods for the other two. As I said, this is going to be a long thread ;)

Edited by ChinRey
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The reason for high LI is usually either too many triangles (not the case here) or something about the physics shape.

An easy way to skyrocket your LI is to make a physics shape with small gaps in it. What does the physics shape for your photo frame look like? Did you make it hollow? It should be just a solid rectangular box. (Don't go for realism when making your physics shapes, keep it as simple as you can get away with.)

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The clothes hook bench has 7 objects (5 lamps plus camera so 1 object to import I think) and the picture frame shows 12. Even discounting the lamps and camera, it looks like the picture frame will import a link set of 7 objects. Is this true?

 

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HI all,

Thanks for the replies. The picture frame in this pic is my 3rd attempt at modeling it. The clothes pins were over 500 poly each so I was simplifying the mesh since it was so small. The model prior to this that I tried to upload was a little higher poly count, probably a couple hundred more poly but it was 3 objects, each photo area was separated because I couldn't figure out how to get my photos taken inworld to fit the face correctly.

I found a thread that someone explained how to do have one object photo frame work correctly so I was trying it again.


@Wulfie Reanimator You may be right about the physics, I made a simple V-Shaped box around the shape of the frame, but I removed the top and bottom faces thinking this would reduce the polys on the physics (because I didn't know if that mattered).

I will test it again later today after I finish re-working the mesh.

Thanks for your help!

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36 minutes ago, CharleeDavidson said:

The clothes pins were over 500 poly each so I was simplifying the mesh since it was so small.

500 polys for a clothespin! 😲. Yes, you definitely wanted to do something about that.

 

39 minutes ago, CharleeDavidson said:

@Wulfie Reanimator I made a simple V-Shaped box around the shape of the frame, but I removed the top and bottom faces thinking this would reduce the polys on the physics (because I didn't know if that mattered).

It shouldn't matter very much but what you really need for physics, are four square srufaces, one for the front and one for the back of each frame.

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10 minutes ago, ChinRey said:

It shouldn't matter very much but what you really need for physics, are four square surfaces, one for the front and one for the back of each frame.

I'm not sure what you mean, but this is what I mean. Brighter-orange box should be the physics model.
b7489dc5c3.png

(Excuse the hilariously oversimplified 30 second remake of OP's model.)

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8 minutes ago, Wulfie Reanimator said:

I'm not sure what you mean

Something as simple as this:

image.png.57be6a3d596216a49e5858186e0a23dd.png

Possiblydouble sides with surfaces facng both inwards and outwards but even that may be overkill. You don't even have to make it the same size or proportions as the visual model since the uplaoder will scale it for you. Just make sure the angle points the same way in both models.

It's important to keep in mind that the physics model's only function is to keep avatars (and on some rare occasions physical objects) away from places they don't belong. In this case you only want to keep people from walking straight through the frames and this simple model is all it takes to achieve that.

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6 minutes ago, ChinRey said:

Something as simple as this:

Possiblydouble sides with surfaces facng both inwards and outwards but even that may be overkill. You don't even have to make it the same size or proportions as the visual model since the uplaoder will scale it for you. Just make sure the angle points the same way in both models.

It's important to keep in mind that the physics model's only function is to keep avatars (and on some rare occasions physical objects) away from places they don't belong. In this case you only want to keep people from walking straight through the frames and this simple model is all it takes to achieve that.

Ah, yes, that would work fine.

Here's an extreme example of what I was talking about:
c7899395f6.png

That's 5 x 5 x 2 meters, same model used for mesh and physics. 5 LI by default, 4 if you make it larger.
But if you make it smaller, it becomes 10 LI at 50% scale and 20 LI at 25% scale.

If those cylinders were more separated, they wouldn't get so high LI so quickly. (But after a certain point, the physics shapes are simplified automatically and the LI drops to 4 again.)

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Thank you all for the help!

I re-meshed the clothespins to lower the polys on them, reduced it by a couple hundred or so.

I took your advise, @ChinRey and just made a simple V-Shaped single-sided plane for the physics.

I read a thread about how to make a picture frame work so inworld pics would fit perfectly, so I was able to join the entire mesh and upload it as 1 object, with 6 Faces.

The total LI now is 1LI. It was originally 2LI but it was fairly large and out of proportion compared to my avi, so I resized it inworld which lowered the LI.

Thanks again for helping me figure this out!

Here's a pic of it inworld and textured.

 

Finished Frame.png

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There's also the size of the model in the mix as well, if it's massive when you spawn it in SL, you might want to downscale it back in blender.

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