+1 yespls. Issue is becomeing more and more prevalent as PBR makes its way through.

With ALM, it was easier to go un-noticed: people could diffuse-texture an object w/out seeing a jump in LI until they added extra maps; when they saw the jump in li, they could remove the maps. This isn't possible with adding a PBR material, and the various bits of trickery (invisible physics prims and linked pieces set to Physics type None) are non-obvious.

Whether the li issue is addressed directly of not, there to be a viewer-side piece of UI that can stop the action, warn the user that li is about to increase beyond a certain threshold, briefly state , list steps they can take, and prompt whether to actually continue the operation. Otherwise, the misperception that "PBR takes up more Li" can't be addressed accurately, and the problem of content getting auto-returned etc can't be fixed knowligably by the end user.

Hello, and thank you for your detailed bug report regarding the increase in land impact when materials or alpha modes are applied to hollow prims. This issue has been previously reported in our Jira archive under the title 'Alpha Mask increases Land Impact on old prims ridiculously.' We understand the significant impact this has on builders and landowners, and we have set this issue to tracked. We have no estimate when it may be resolved, but please keep an eye on future updates. Thank you for your continued commitment to improving Second Life.

I can reproduce this with a cylinder and a hemisphere linked togehter. Land impact increases from 1 for each prim to 2 for both linked together.

As soon as I have hollow > 0 for the hemisphere as a part of the linkset the land impact increases to 51 for the linkset.

I suppose a mesh object would be the better choice.

https://gyazo.com/6bb98600a6883c9165fd5006e7ee8f7d

This is a problem that's been around since they first implemented materials(normal and specular). I actually reported this on the old Jira when it first released, giving examples because this affects some regular non-hollow prims, even if you set the diffuse to masking and don't apply other materials. This was however closed by Melissa Linden and was told "Reduce the faces of the mesh" ignoring that I had mentioned it was prims.

I am not an expert in this subject, I am only forming this hypotheses by piecing together a much larger puzzle with what happens with mesh objects in general, but most of this I am sure and confident is correct:

What is happening is when you apply materials to an object, it switches to a different impact accounting mode called "New" or "Mesh" - it's the same accounting that Mesh objects use. This means that the prim's stats are now the greatest of Download, Server, and Physics. Yes, that's right - your hollow object is now counted as mesh, even if it's not.

Now why is that such a huge deal? - Physics. That's where it really gets you. Now here's where I am forming a hypotheses - what I believe is happening is, originally, the object counted as a single physics object that was easy to calculate in the Havok engine. A cube is a cube and a sphere is a sphere. Simple enough, right? Right. So all of that, and land impact for physics stays well below 1. Since all linksets must have a minimum impact of 1.0, this gets rounded up and that becomes your accounting. Now - when you add hollow to the mix, that ups the physics complexity of the object considerably. It's especially hurtful if it's really small because that's bad for the physics engine. To make matters worse, now physics is entirely hulls of the object, and not simply the object's core as it was before.

All of this contributes to adding a massive impact to the physics cost, which causes such an inflated land impact for the object in question.

The only way to "solve" this isn't to just "correct" the physics cost - 1 LI for such a terrible physics impact is in fact, bad for the region in the first place, so the new physics accounting is in fact the more correct one. You have to tell the physics engine that your object is still, well, solid. This can be done in the "Features" tab of the object, changing the physics shape to "Convex Hull" instead of "Prim". This causes the engine to count only the exterior verteces of the object when forming its physics shape, which in turn is much more pleasant for the physics engine to deal with - and off your object goes on its merry way to a lower than 1 LI again. Problem solved.

I made a single prim with LI near 5K by torturing and applying materials.