Sculpted and Mesh, they don't like each other much?

[Six Igaly]

Take 2 sculpted mangrove trees both with a landimpact of 5. Link them to a regular prim (root). 5+5+1 = 11. So far so good.

Then take a mesh oil drum with a landimpact of 2 and link it to the linkset as just described, so the regular prim stays root.

Now you see this: 5+5+1+2 = 182. I know math is not my strongest point,  but this is obvious not good. I'd better check all the linksets on the sim now. Who knows how many people 'lost' prims this way without being aware of this.

Well the bright side is I was surprised again by SL :matte-motes-big-grin-squint:

[Maeve Balfour]

Meshes are subjected to LL's new Land Impact system, which encourages mesh creators to work efficiently and keep server load and render load to acceptable performance levels. If a mesh is badly made and INEFFICIENT, the Land Impact costs rise accordingly - so if a mesh creator designs their work well, they are rewarded with a low Land Impact cost. Kind of like a carrot on a stick reward system...

However, standard Sculpties and Prims are NOT held to this new mesh-based Land Impact System by default. A sculpted prim by its very nature is very inefficient in its render performance in comparison to general meshes, but to avoid breaking legacy content, LL has let them retain their original Land Impact settings - One sculptie = 1 Land Impact etc.

BUT... and this is a BIG but.....

As soon as you attempt to LINK any sculpted prims TO a mesh object, the Sculpties are THEN converted to the mesh equivalent Land Impact system. If nothing else, this just shows how BIG a performance difference there is between the mesh oil drum you described (Land Impact of 2 (MESH Land Impact measurement)) and the sculpted mangrove trees (originally with a standard Land Impact of 10, plus the root prim = 11). What I assume in this case has happened is that the original (legacy) 10 Land Impact cost of the sculpties has become 179 Land Impact when converted to the MESH Land Impact system. The mesh oil drum itself is fine and very low impact by the sounds of it... just that the equivalent cost of the sculpted mangrove trees has jumped sky high when their true impact cost is converted to the mesh measurement system.

This gives a bit of an idea of the uphill battle mesh creators have been facing just to compete with the legacy sculpties, despite the vast performance benefits mesh has. Unfortunately, this disparity is necessary otherwise pre-existing content would be rendered useless if converted by default to the mesh measurement system.

It's fully understandable WHY LL had to adopt this system for mesh - If mesh had not been subjected to these new Land Impact conditions, encouraging mesh creators to work efficiently, then the SL servers would never have been able to cope in the long run with an inevitable influx of massively complex, badly made mesh objects.

So for the case you mention, and in general: Just DON'T link meshes to sculpties. It can be a pain, but it's the only safe way to avoid these massive Land Impact spikes. Linking sculpties to meshes will automatically convert the sculpties to the mesh Land Impact system, and as you found, potentially cause an unpleasant surprise with their resultant cost.

:matte-motes-smile:

EDITED TO ADD: A potential BONUS, though, is that any UNCUT, STANDARD CUBE prims (NON-sculpties) can be opted INTO the mesh measurement system, simply by changing their physics shape type (in the build menu) to Convex Hull.
WHY? Well, prim CUBES by their nature are very low impact. In the default Prim Physics Shape, a single cube = 1 Land Impact. However, convert the same prim cube to a Convex Hull Physics Shape, and its Land Impact is reduced to 0.5 (half). This won't be immediately obvious, since SL automatically rounds to the nearest FULL number for Land Impact. BUT, LINK TWO of these cubes together, and their combined Land Impact (0.5 + 0.5) will equal ONE. This is a big bonus of the mesh measurement system... for meshes mostly, but for standard cube prims as well.
So if you have any of your own uncut prim cubes around, try this out - you could save quite a lot of Land Impact cost.

(NOTE: I think this only works with standard, uncut prim CUBES. Other prim types are less efficient. DEFINITELY DON'T try this with torus prims! (they are massively inefficient for physics calculations)).

[Six Igaly]

Thank you for this clear explanation Maeve :matte-motes-grin:

I learned as soon as I linked them because I always check, check and check again. And in my case it is not a pain, I just wanted to place some stuff off sim without using to much prims ahha. And yes, the mesh drum is very fine. I already figured it had to do with the measurement. I just wanted to share my surprise LOL.

[Maeve Balfour]

Ah.. linking for off-sim placement...!  Yah, that would be annoying for sure! I can empathise with your disappointment there.

But you are correct though, that this issue hasn't been well publicised in general, so there are no doubt plenty of residents getting rude wake-up calls with the Land Impact spikes via sculptie linking. It's a pity, because I would guess that many would blame mesh outright for the problems without really understanding the reasons WHY the impact costs spike.

:matte-motes-smile:

[Six Igaly]

Unfortunately indead people will blame mesh in similar circumstances. I know better though because I also know (without fully understandng it yet) that when you link mesh objects together (in some cases anyway) land impact will decrease. At least I experienced this with a custom mesh object I ordered recently. 2 linked together shows a landimpact of 1 while unlinked they both show as 1=2. But besides that, mesh objects are looking great!

[Jenni Darkwatch]

Normally, if you look at the actual weights of sculpts, you should see the impact they would have if linked to mesh. That is, click on the "more info" link and check the first three weights. The highest of the three with sculpties is usually the download weight, and it's significantly higher than the "legacy" land impact of sculpts. Small sculpts actually may end up having relatively small weights, it's the large ones like trees and massive rocks that will blow the weight out of the water.

[Six Igaly]

Thanks Jenni, this "more info" panel makes a bit more sense now (to me that is) :matte-motes-big-grin:

--||-

[Maeve Balfour]

Six Igaly said: I know better though because I also know (without fully understandng it yet) that when you link mesh objects together (in some cases anyway) land impact will decrease. At least I experienced this with a custom mesh object I ordered recently. 2 linked together shows a landimpact of 1 while unlinked they both show as 1=2.

...................

What you are seeing there is the rounding of decimal points of each mesh's individual Land Impact, when they are linked together. For example, say you had two mesh objects with individual Land Impact costs of around 0.5 each. UNLINKED, SL will display their cost as 1 (because SL doesn't show prim cost / Land Impact with decimals; it rounds the figure UP or DOWN to the nearest full digit). However, if you LINKED these two objects together, you would reap the benefits of the mesh measurement system... as in with the rounding of decimals: 0.5 + 0.5 = 1 Land Impact (LINKED). This is the rounding to the nearest digit working in your favour.

IF possible (depending on perms, and IF it's safe to do so with purchased items), you can save a nice amount of overall Land Impact as a builder when you link meshes together as much as possible. Link them and round out their decimals - sometimes, it pays to experiment a little bit with WHICH meshes you link together - some combos will yield better savings than others... most likely down to whether objects have a high decimal or low decimal in regards to which way they round out. (1.2 unlinked would show as 1; but 1.7 unlinked would show as 2).

So for example... two meshes @ 1.8 and 1.8 would show as 2 Land Impact cost each UNLINKED (4 in total).... When LINKED up, their decimal rounding... 1.8 + 1.8 = 3.6. Rounded out, that would still cost 4 Land Impact in total. HOWEVER, if you had a stray 0.5 mesh nearby... LINK that in... 1.8 + 1.8 + 0.5 = 4.1  ....which would then round DOWN to 4 Land Impact (so that stray 1 Land Impact mesh would become a free object, in essence). NICE!

Also, the LOWEST possible Land Impact cost for a mesh (or any object) is 0.5.... which UNLINKED will show as 1 Land Impact. So it's always worthwhile to experiment with mesh linksets!

:matte-motes-smile:

EDIT: Please forgive me if I have messed up my calculations at all LOL... I am almost asleep at my keyboard (3.45am!) :matte-motes-yawn:

[Six Igaly]

---

Also, the LOWEST possible Land Impact cost for a mesh (or any object) is 0.5

.... which UNLINKED will show as 1 Land Impact. So it's always worthwhile to experiment with mesh linksets!

---

Oh I will, I like experiments to gain more with less.

---

EDIT:

Please forgive me if I have messed up my calculations at all LOL... I am almost asleep at my keyboard (3.45am!) :matte-motes-yawn:

---

In about 12 hours i will be in that same condition, so know what it is so forgiven :matte-motes-big-grin-evil: 

[Alicia Sautereau]

Just link all your regular cubes and cylinders and set them to convexhull, you save 50% on prims

Got another ~370 "free" prims that way :matte-motes-silly:

 

 

Just don`t unlink when you don`t have enough prims on the land lol

[Kwakkelde Kwak]

I did the same, saving 100s of prims on our homestead sim. Be careful though with hollow objects, since a hull is well...a hull. Any twists or tapers will cause problems aswell I bet.

[Six Igaly]

Also @ Kwakkelde

Oh yes I've read about this before and played around with it. Hollow objects are better not included in those linksets if you want to walk around in them :matte-motes-grin:

[Josh Susanto]

>5+5+1+2 = 182.

This is because, as has been explained to me, mesh is not overcharged, but everything else is undercharged.

And somehow, that didn't matter for about 10 years.

Hmm.

[Davido Chrome]

They want us to optimize our builds. And I think they are right too, any other online game that introduces new content has hyper optimized the objects they introduce. In Second Life the users make the content. So Linden Lab is trying to do something about the lag problems by encouraging people to optimize their builds.

And the thing is, with any Mesh build that is optimized correctly, you get a whole lot more detail for your Lindens than you can ever get with sculpties. Mesh IS cheaper AND has lower land impact (in relation to the amount of detail you get), when done right.