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Leeza Catteneo

PE - Reasonable PE for attachments / accessoires

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Hello =)

I read some threads about the PE (prim-equivalent) and wanted to ask the question what PE value would be acceptable by the vast SL community (means: by you) =D

Remembering the discussion about rendering costs a while back I thought it would be interesting to think about the opinion regarding reasonable average and maximum PE values for avatar attachments/accessoires.

My point is: If you sell meshed items with too much PE (in the opinion of too many people) it could affect the business negatively at some point.

For example: I made a ~60PE  item which looks ok but hardly better than a sculpted version would look like. It looks really awesome (including the "yay mesh" effect) with ~230PE, tho.

But would that be too much? What would you consider an 'ok' PE value and where would you see the limit.

 

Have a great time!

Leeza

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Considering that most of the SL population has under 200 prims to work with on their land/parcel I would say that both PE amounts you just described would be way too high.

If you were making it strictly for yourself and any of your friends that just had to have one cause it was just sooo mesh cool and didn't care how much the PE was, that would be different and totally up to you or your friends to waste as many prims on ineffective mesh optimization. But if you are going to sell something it is imperative that you learn how to optimize your mesh. That much PE for something that is an accessories as you say is way to much, making something look good is not done by clicking subdivide unless you know what you are doing, it is done by properly placing the edge loops so that you can hold the shape you want with as little geometry as possible. Hope this helps :D

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Thanks guY!

And for accessories attached to the avatar? Like Shoes, Shirts, Hats, Hair and such? Stuff you would hardly put on the parcel ground but to the avatar attachment points?

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When you attach stuff to your avatar it doesn't count against the land/parcel prim amount but it does count against the arc that other residents will be affected by as well as yourself. 

I think a good rule to keep in mind is think of if you made something out of sculpties and how many prims it would be, you wanna be less than that, after all that is what mesh is supposed to be doing is saving us from the lag monster that sculpties are. The only reason why it would be more PE than its sculptie counterpart would be if you have soooo much detail to warrant it and even in this case only maybe a few PE more than its sculptie counterpart. Hope this helps :D

Remember as little geometry as needed to hold the shape. Look into topology optimization and layout techniques to help you achieve good edge flow.

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PE is as much of an arbitrary bogus number as ARC. I doubt that people with mesh attachment will get anywhere near the typical avatar polygon count that we're seeing right now, not to mention the polygon count of prim clothing in pre-sculpties days:

 

avatarmesh.jpg

 

So why not go all the way up to 256? Make it look as good as possible. Nobody cares about the PE of attachments, they just have to look great. Mesh will still greatly reduce the overall polygon count. Or at least it would, if LL ever got off their ***** and turned viewer 2 into a decent SL client that people don't mind using.

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Haha! Thanks for the answer =D

I have an item already uploaded to SL made of 6 (64x64) sculpty prims. Now I uploaded the same maya scene as a mesh and went all the way up to 930 PE =D Of course it would never have the same PE if I'd remodel the same item from scratch and optmized for mesh.

 

But does the amount of sculpty vertices affect servers and such exactly like vertices of mesh does? If so... then reducing the amout of vertices/polygons would be the real deal instead of watching PE, right?

 

Ps: Is 256 a "magic" number regarding PE?

 

 

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You surely don't want to make 256 PE attachments. I'd suggest that you focus on triangle count since there are already standards for triangle count in game art. Granted, you could play with those numbers a little since SL doesn't have normal maps which can give the illusion of more detail with less polygons. It will take a little time before the SL community starts making its own "PE" standard.

Ok, so to throw out a practical example, I've been experimenting with rigged clothes. None of them have had a PE higher than 4. (Also, note that the PE for something rigged is higher than the same object not rigged.) I'd say that a good maximum triangle count for a single attachment is 4000 triangles.  And, that is a lot. Most items wouldn't need near that much. But, if you find yourself over that number, you really need to ask yourself is it really necessary. Consider that some games use 10,000 triangles for a whole character, clothing and all. (Some do have substantially higher of course. You can see the ranges in the article link below.)

Here's a good page to read. At the bottom, you will see links to articles on typical game triangle counts. It will give you an idea of the acceptable ranges out there. http://wiki.polycount.com/PolygonCount

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Leeza Catteneo wrote in part:

 

But does the amount of sculpty vertices affect servers and such exactly like vertices of mesh does? If so... then reducing the amout of vertices/polygons would be the real deal instead of watching PE, right? 

 

All that matters for your graphics card is the number of polygons / vertices and the amount of texture data. It doesn't matter if the polygon mesh is generated from prim data, a sculpt map, or a Collada file. The PE number doesn't really mean anything, it is just a way to keep the old prim limits alive and ensure that people won't tier down.

 


 

Ps: Is 256 a "magic" number regarding PE? 

256 is the highest number of prims that can be linked, and some hair designers manage to get very close to that number. I'm guessing that mesh attachments are also capped at 256 PE, but I could be wrong. I don't mind as long as it looks good. If my avatar lags people, they either need a faster PC or more reasonable graphics settings :)

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Ashasekayi Ra wrote:

 I'd say that a good maximum triangle count for a single attachment is 4000 triangles.  And, that is a lot. Most items wouldn't need near that much.

Thank you =) 

The actual item (non rigged attachment) has a Tris Count of 5000 and a PE of 230. The "lo-fi" version with only 2900 Tris gets a PE of ~130  >.< 

And thats why I wondered because I have done some "Next Gen" modeling and never went over ~5000 Tris

It would be no problem at all to keep the same item down to ~1600 Tris even. But of course it wouldnt look as smooth and clean as a ~5000 Tris item =D

I wonder why my ~5000 Tris item has a way higher PE than your 4000 Tris items =)

 

BTW: Everything tested was not rigged and uploaded only in the highest LOD spot. All other 3 spots where set to NONE and are empty.

 

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Ishtara Rothschild wrote:

 I don't mind as long as it looks good. If my avatar lags people, they either need a faster PC or more reasonable graphics settings
:)

No you would be the only one seeing your avatar as you would be auto muted by the viewer. So then you will have to say to yourself wow people will slow computers are just not as good as me, with my top-o-line windows PC. LOL........not

 

IMHO if you don't care about the lag caused by what you create, then that is fine, homestead sims provide a place for you to be where you don't bother any people but the ones that wanna think they are the coolest with their 6K arc avatars :D weather the arc number is accurate or not, lag is real thing, and mostly it's caused by people that don't care or don't know what they are doing :D

 



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5K tris should not equal that much PE there is something else wrong. FIrst don't leave the others set to none that will raise your PE, it is at least best to use the auto generated ones if you are not going to provide your own. I personally don't upload the other LOD levels unless its a finished model, when I am just testing I upload the hi-lod and auto generate just to see how it looks but I am not really taking into account the PE at that point. Once I have achieved the topology I am looking for I then create my lower LODs and add them getting to the best possible PE. No pysics shape for avatar but for attachments a simple sprite or even cube will greatly reduce your PE.

Remember PE cost is the greater of the three weights rounded up.

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Leeza Catteneo wrote:


I wonder why my ~5000 Tris item has a way higher PE than your 4000 Tris items =)

 

BTW: Everything tested was not rigged and uploaded only in the highest LOD spot. All other 3 spots where set to NONE and are empty.

 

That.

 

When you put the other LODs to none, you lose all the benefits (and the PE savings) from having lower poly LODs.  Each LOD should be made to be about 1/2 to 1/4 the number of polys of the next higher LOD (this maximizes the PE savings).

So, to get the cheapest PE, your mesh should have a highest LOD of ~5000 tris, the next LOD should have ~1250 tris, the next should have ~315 tris, and the lowest LOD should have ~75 tris.

Also, make sure to define the physics shape or as simply as possible (especially for attachments) since they'll be phantom anyway when attached.  A simple 12 triangle box or even a 4 tri tetrahedron will do.  This will also reduce the calculated PE.

 

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Wow ok. So filling the LOD spots in the way you described would reduce the overall PE for the item? Will the PE differ depending from which distance I "inspect" the item or will the overall PE be lower in generell?

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@Ishtara: Actually the attachment limit is still 256 prim units which doesn't correspond to PE. We asked about this in one of the mesh meetings. If you look at a mesh in the edit window, you will notice there is a prim count and a PE count. A mesh prim  is one whole, indivisiable piece. So, if I upload mesh hair that is joined into a single model. It would be 1 mesh prim but its PE could be 10 (or whatever). Now, if I use SL to link a single mesh hair bow to that mesh hair, now I have 2 mesh prims and whatever the added PE of them is, which in this example could be 12 PE.

@Leeza: There could be a number of reasons your 5000 triangle object is that high. You'd have to give a description of what it is. What's the scale? Did you use a custom low poly physics shape? If not, did you decompose the default physics shape? Did you use LODs? Did the LODS decrease by a factor of 4 (approx.)? Were there any regular prims linked to it?

All these factors can dramatically change the PE.

Edit: I just saw your post while I was typing. lol Yes, leaving all those LOD spots on none is a big no no. That means those 5000 triangles are left on for every LOD. That will make the PE sky rocket. Plus, you are forcing someone's viewer to render 5000 triangles they can't even really see from 256+ meters away.

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Ashasekayi Ra wrote:

Edit:
I just saw your post while I was typing. lol Yes, leaving all those LOD spots on none is a big no no. That means those 5000 triangles are left on for every LOD. That will make the PE sky rocket. Plus, you are forcing someone's viewer to render 5000 triangles they can't even really see from 256+ meters away.

Whohoo xDD

Ok! Well, that's my bad then, haha. Because I was too lazy for "just testing". Plus I thought keeping the LODs empty would save me PE. Although I wondered who would use LODs to "lower the quality if it works just perfect with just one LOD" anyways  ... *runs and hides =D

The scale is actually very low since it's a pair of sunglasses. It is made of 4 different Objects in Maya and exported as selection. No other stuffs involved, yet =D No prims, no scripts and textures are uploaded separately.

Well, and I didnt use any physics shape either >.< I think I should do that! I guess.

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Ok, it is starting to become clear why you had that crazy PE. The issue of the LODS is one part. The other issue is that if you have something that small, and you don't even touch the physics tab, a default, dense convex hull physics shape will be uploaded with it. Small, dense triangles in the physics shape will cause the physics cost to sky rocket. You'll want to atleast just export out a simple cube and upload that as your physics shape. That will give you a tiny physics cost. The final PE is whichever number is the largest out of download, server and physics weight. The "none" in LODs affected the download weight. I'm not sure if it was the LODs or the physics that did the most damage. But, the next time you test the object, you can take a look at the list of the 3 costs on the upload window.

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From what I can see I understand that it's clearly the "none" in LODs which made the huge PE value. Now I'm down to 21PE instead of 230PE. What a difference! And that's by quickly creating dirty reduced versions of the actual item. And I believe this is an acceptable PE for attachments =D

 

Thanks a lot!

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For something this small, as long as physics cost is kept low, the PE will be very stronlgy dominated by the lowest LOD triangle/vertex count. Make that as simple as you can bear. Attachments don't have physics, so you can make the physics shape a simple cube and decompose it. That will give a physics cost of 0.36, which will always be smaller than the server weight (0.5 if it's one mesh).

**Edited ... was thinking of rigged attachmenhts for LOD distance. :matte-motes-agape:

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Is it a must to create a physic shape for every mesh one uploads in order to lower the PE? I know that structures require a phsyic shape in order to walk in, but what about prim attachments? If you dont create a physic shape, will SL make one for you instead?

I'm not sure if I understand above posts right.

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StoneDwarf wrote:

Is it a must to create a physic shape for every mesh one uploads in order to lower the PE? I know that structures require a phsyic shape in order to walk in, but what about prim attachments? If you dont create a physic shape, will SL make one for you instead?

I'm not sure if I understand above posts right.

Yes, because the uploader will attach a default convex hull physics shape that is usually too heavy no matter what the object is. The theory is that even rigged mesh have the chance of being rezzed to the ground for whatever reason.

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Leeza Catteneo wrote:

From what I can see I understand that it's clearly the "none" in LODs which made the huge PE value. Now I'm down to
21PE
instead of
230PE
. What a difference! And that's by quickly creating dirty reduced versions of the actual item. And I believe this is an acceptable PE for attachments =D

 

Thanks a lot!

Welcome :)

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I'm currently experimenting with mesh footwear as attachments, and in regards to prim equivalency (tris) they compare very efficiently when compared to building the same in sculpties.

It's the LOD factor and associated cost that pushes the PE factor up - being smallish items in the world view, the LODs drop away very quickly - it is something I am still experimenting with, and so far have yet to get around to creating my own customised lower LOD meshes (due to lack of time for now, I am just using the default LODs for testing purposes). Currently as an experiment I am using the full LOD mesh for the first three LODs, and a very high minimum LOD - not efficient at all, but as a basic proof of concept still very favourable in comparison to an equivalent sculptie build in PE costs. No doubt when I get organised, and create proper, optimised 3rd and 4th LOD meshes, this will improve the PE considerably.

The high level of control for texturing via UV's more than makes up for the hassles of PE control, in my opinion.

At the moment, with the unoptimised LODs pushed very high, my experimental shoe build is hovering around 30PE - a similar style shoe I bought inworld made from sculpties is around 40 prims. With a bit of work on making proper LOD meshes, I reckon I could push my PE down much further.

Also, using a simple box as the physics mesh drops the PE by a big degree (as far as I know, all mesh requires some kind of physics shape, regardless of whether they will actually need physics or not... I should model up a simple 3-point physics triangle for my next project).

All in all... mesh as attachments has a lot of potential :matte-motes-smile:

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