Saturday, July 26, 2008

Avatar Rendering Cost

Photo By Sweetie
Written 23 July, 2008

Avatar Rendering Cost

The prims attached to (i.e, worn by) avatars don’t count against a sim’s prim allowance, but the simulator still has to rez them, move them, make them flexible or sculpted, and run any scripts they may contain. When there’s a crowd of avatars wearing elaborate jewelry, prim clothing, and hair, the load can be considerable. It’s not unusual, for instance, for a single piece of jewelry to have 250 prims. Twenty avatars wearing only that object would require the sim to rez and maintain 5000 prims; that’s a third of the sim’s prim allowance of 15000—and MORE than the number of prims allowed on an openspace (light) sim.

Viewer-side, particles given off by the attachments of other avatars and the textures of the clothing and hair they wear must be rendered. This can kill frame rate.

All of this explains why we’re often asked to quiet or remove our scripted objects when we attend concerts and other large assemblages of avatars.

Several months ago the Lindens introduced Avatar Rendering Cost (; Blogger won't take the URL today), a number that reflects the load placed on a server by an avatar and her attachments. Turning on ARC lets you know not only YOUR rendering cost, but that of every other avatar present.

ARC is calculated with a point system, with points awarded for each prim, for each texture, for use of rotation, texture animation, or other scripts, and for use of light, glow, and flexi or sculpty characteristics. An occurrence in each category for each prim generates only one point, but they can quickly add up for complex objects.

Take Sweetie, for instance.

Or, rather, take one of Sweetie’s outfits, an elaborate Asian gown.

When she tried it on the other night, she complained her frame rate dropped dramatically. So I told her about ARC, and we both turned it on.

OMG! She had an Avatar Rendering Cost of 13,000!

Now when I rig myself out formally, wearing shoes, prim clothing attachments, hair, and earrings, I’ll usually have an ARC of 1000-1100. So what was up with Sweetie’s 13k?

When we examined Sweetie’s outfits, we learned that each of more than a half-dozen attachments were made with 150 or so prims, each of which appeared to be flexible, and many of which were sculpted. Cumulatively, the outfit was just over the top!

Beautiful, to be sure. But over the top? Definitely. It was a sim crasher.

1 comment:

Anonymous said...

Well, i am up for everyone to know what AVs are causing them lag, but i make jewelry and it is difficult to use few prims, sculpted prims have a rendering cost of a torus so special attention to them is not necessary. What are the bigger lag causing item are flexi prims that have a high flexi setting (3) is highest. However i have already seen people on a which hunt for high ARC. I tend not to discriminate AVs based on how they choose to look. So solution is easy, just mute AVs with high ARC, they will become ARC = 1 if you have avitar imposters enabled in the graphics settings. With that said i have one alt i use that i mute anyone over arc=500 and well if i go some place it loads really fast and no lag, but 90% of AVs will be Muted :) Ahh yes my record ARC for my character (just testing) is arc = 450,724 (not a miss print my average is arc=480.