Q: land impact slowly creeps up

[Tator Market]

I made some roads.  I uploaded them @ 3X through Firestorm Viewer.  They uploaded at 1 and 2 land impact.  I worked really hard to do everything I could think of and was quite pleased with myself for about 20 minutes.  After that, the 90 degree turn went from 2 LI to 13 LI.  The 45 degree turn went from 2 to 23 LI.  23 will not work when you're trying to build a very big track and only have a small number of prims to work with.  After some more research I found out that SL calculates 2 sets of LI, one for regular prims, and the other for mesh.  These run parallel, so SL can sometimes switch from the old way (prims) to the new way (mesh) or vice versa.  Why would it let me upload it at 2 but sneak up like that?  Does anyone have a suggestion that I haven't tried?

Suggestions for fixing it thus far (I've tried all of this and many combinations):

• turn convex hull back on (works, but these roads have side walls so you can never get down to the track with convex turned on),
• make a linkset with the parent prim being a prim that's set to convex (just makes LI go up.  Even tried multiple normal prims set to convex.)
• turn off materials (glow, bump, etc - had no impact)
• not resize it after you upload (took 20 minutes to creep back up)
• resize it (I shrank them - no bueno)
• don't texture them (no impact)
• don't upload with textures (didn't)

[arton Rotaru]

1 hour ago, Tator Market said:

I made some roads.  I uploaded them @ 3X through Firestorm Viewer.  They uploaded at 1 and 2 land impact.  I worked really hard to do everything I could think of and was quite pleased with myself for about 20 minutes.  After that, the 90 degree turn went from 2 LI to 13 LI.  The 45 degree turn went from 2 to 23 LI.  23 will not work when you're trying to build a very big track and only have a small number of prims to work with.  After some more research I found out that SL calculates 2 sets of LI, one for regular prims, and the other for mesh.  These run parallel, so SL can sometimes switch from the old way (prims) to the new way (mesh) or vice versa.  Why would it let me upload it at 2 but sneak up like that?  Does anyone have a suggestion that I haven't tried?

Suggestions for fixing it thus far (I've tried all of this and many combinations):

• turn convex hull back on (works, but these roads have side walls so you can never get down to the track with convex turned on),
• make a linkset with the parent prim being a prim that's set to convex (just makes LI go up.  Even tried multiple normal prims set to convex.)
• turn off materials (glow, bump, etc - had no impact)
• not resize it after you upload (took 20 minutes to creep back up)
• resize it (I shrank them - no bueno)
• don't texture them (no impact)
• don't upload with textures (didn't)

Sounds like the physics shape is too complex. There is a More Info link in the build flater. This will show the weights, Download, Physics and Server weight.
The highest number of these 3 will be the land impact for mesh accounting. When changing the physics shape type to Prim, it's likely that the Physics weight is going up.

Here is what I do with roads. Creating a very simplyfied physics shape for each section, just the bare minimum you can get away with. When uploading, don't press the Analyze button. This will leave the physics as triangle based physics shape. It will let physical vehicles actually ride on the surface instead of hovering 5 cm above the surface.
Plus: Omit the vertical faces where your road pieces connect in the physics shape. Otherwise cars will jump at these connection seams.

Now the gotchas. When using a trangle based physics shape (Non analized) you will have to make your mesh at least 0.5 meters large in all 3 dimensions. Is one dimension less than 0.5 meters, the physics engine will secretly switch to the default single convex hull physics shape.
Furthermore, a triangled based physics shape will increase in land impact (Physics weight) when shrinking. While analized physics shapes will keep their weight regardless of the scale.

[Wulfie Reanimator]

Posting some stats about the uploaded model would definitely help to pinpoint how to solve the problem.

The scale at which you upload the model doesn't affect the actual LI once in-world and correctly scaled.

[Tator Market]

arton, you are my hero today! I was pulling my hairs out!  I made my 10th set of roads and thanks to your suggestions, the roads are holding LI! So far it's been an hour with no changes in LI.  I also had the road bumping which you mentioned and taking off the ends fixed it.  Thank you SO much! I can finally get to buildin' my track!💖