Tips & Tricks

How to reduce an items prim count

Land Impact is the new way of calculating prim usage and is what you should use to work out if you’ll have enough prims on your land to rez things.

Because of the way my items are built, in the vast majority of cases you can drop the Land Impact of it by changing the prim type of the item to Convex Hull. It only takes a couple of minutes and it easy to do.  As long as you don’t fiddle around with anything else, you can’t break it.

You can even do this on the couples SDA poseballs.  It should get you a prim back for each couples set.  It will work on the majority of [SDA] Satiated Desires Animations, Satiated Desires and The Mistress Salon items.

How to change an item to convex hull.

I’ve used the Wall Restraint for this example.  It’s current prim count is 18 but by changing it to Convex Hull, I can reduce the Land Impact to 12.  That’s 1/3, or 6 prims, less than leaving it as it is.

I’m using Phoenix for this as I’m a Luddite.  If you use Firestorm or any of the V2 based viewers I don’t think you see the prim count.  It just gives you the land impact.

1.  Right click on the item and select edit and look at your prim count.  The Land impact count is in brackets and is currently the same.  If you’re using a V2 – make a note of the Land Impact number.

2. Click on the features tab and on the top of the right hand side column you’ll see a heading called Physics Shape Type.  Click on the drop down and select Convex Hull.

3. Check the Land Impact number.  It should have reduced.  In this case it dropped to 12, so that’s 6 extra prims I now have to play with 🙂  If the Land Impact number is higher than before, change the Physics Shape Type back to prim and it will revert back to the old number.


1. LL are still refining the calculation so it may change over time.  If it ever gets bigger than the prim count then just go back to that features tab and change it back to prim.  It will then flip back to the normal prim count.

2. For some of my items (baths and pools mainly) this will stop you being able to stand in the water when you’re not on a poseball.  You’ll need to make the choice between lower Land Impact or aesthetics I’m afraid.

I don’t have a list of what each item will reduce to as I won’t touch them until the next upgrade for each, so it’s a bit of an adventure as to what the final number will be.  For the few items I’ve tried it seems to save around 25% of the prim count.

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