Mesh/FAQ

Note: This page is still undergoing editorial revision!

Why does a mesh cube have a land impact of x when a prim cube is 1?

Prim count was not a realistic weight of the objects' resource usage and how they affect performance. However, we are not changing their contribution to resource costs on legacy objects in order to maintain existing content.

Why does my object's land impact depend on the object's scale?

Larger objects do use more streaming and physics cost resources -- they are visible from a greater distance (which means they need to be streamed to more viewers in an area) and they have a larger collision cross-section in the physics engine.

Why do meshes have x land impact when they have the same number of triangles as a sculpted prim?

Prim count (in which a sculpted prim counts as 1) was not a realistic weight of the objects' resource usage and how they affect performance.

Why does my land impact go up when I add a script?

The land impact of an object increases when you add a script if the land impact was determined by server weight. This happens only when the server weight is higher than either the streaming or physics weights of the object. Making an object dynamic (physical or scripted) increases the amount of work the server has to do to track that object. Most often, objects have a higher streaming or physics weight than server weight, so this only affects certain server-intensive pieces of content.

Tip: For highly detailed technical information about server cost, see Mesh Server Weight.

Why does my land impact go way up when I link a mesh object to a prim (eg. torus)?

We want to more accurately display the true resource usage of content on the systems of Second Life and your computer. A torus prim is "only" one prim, but it actually creates a much larger load on the physics engine than other, less complex prim types such as a box or sphere.

I linked my mesh to a torus and its land impact went way up. How do I bring the land impact down to a reasonable value?

Set the Physics Shape type of the torus (found on the Features tab of the Build Tools window) to Convex Hull. The hollowness of the torus creates a high computational load on the physics engine. Setting it to Convex Hull simplifies the physics of the torus by putting a cap on the top and bottom, meaning you will no longer be able to stand inside the torus. If you don't need to collide with the torus at all, set the Physics Shape type of the torus to None. Note that the root prim of an object can never be set to Physics Shape type of None.

Why does my prim object's land impact go up when I make some prims have no physics shape?

When any prim in an object is set to a physics type other than "prim", the entire object's land impact is calculated using land impact measurements instead of the traditional prim count. This means that some prims in the linked set may be assigned a cost higher than one.

Why doesn't my mesh import properly?

Please create a thread on our mesh forum ( http://community.secondlife.com/t5/Mesh/bd-p/Mesh ) , and tag it with [UPLOAD]. We're working on creating an upload troubleshooting page, and this will help us to find common trouble areas and answer questions in the future.

I cannot upload a mesh. What are the prerequisites of uploading a mesh?

In addition to the prerequisites listed on Uploading a mesh model, you must meet the following requirements:

• Using a viewer that includes the mesh feature. Second Life Viewer 3.0+ and some third party viewers are able to view and upload mesh content.
• Standing on land that you can build on. This requirement will be removed in the future.
• Using a viewer has the capabilities feature (see bug SH-1030).
• Not experiencing a rare billing bug.

How can I reduce the land impact of my uploaded mesh?

[Need a link to the release 2 viewer]

1. (With the Mesh release 2 viewer): Edit your object and click More Info.
2. Figure out which of download weight, physics weight, or server weight is highest and is therefore driving your high land impact.
   • For objects with a large physics weight, a simple 2 step process can lower the land impact. Set the Physics Shape type of the root prim and any prim that needs a physics shape to Convex Hull, then set the Physics Shape type of the rest of the prims to None. The Physics Shape of the root prim cannot be None.
   • For objects with a large streaming weight, try reducing the scale of the object or provide better-optimized levels of detail that reduce the number of triangles drawn when the object is viewed from a distance.
   • For objects with a large server weight, try making the mesh out of fewer pieces, link small objects together, and remove scripts from the object.

How can I reduce the upload fee of my mesh?

Identify which of download weight, physics weight, and server weight is largest and attempt to minimize it. Click the Calculate weights & fee button to see these weights.

How do I reduce the download weight of my mesh model before I upload it?

Use fewer triangles for each of the levels of detail on the model.

How do I reduce the physics weight of my mesh model before I upload it?

• Physics weight can be minimized by setting Physics > Use Level of Detail to Lowest.
• You can also minimize the physics after upload by linking the mesh to a prim box (making the box the root prim), then setting the physics shape type of the linked set to None. Since the physics type of the root prim of a linked set cannot be set to None, only the box counts toward the object's physics weight.

How do I reduce the server weight of my mesh model before I upload it?

• Use single "large" mesh models rather than multiple separate meshes.
• Separate and unlink active and dynamic content from passive (unscripted, non-physical) content such as walls or landscaping.
• For technical details on how we calculate server weight, see Mesh Server Weight.

How can I make sure my model looks good from a distance?

Experiment with your model on the Aditi test grid. Scale the mesh to its intended size, then watch the model while walking away until you see it disappear. Watch the model as you walk toward it. If the results are not satisfactory, raise or lower the number of triangles in the four automatically generated levels of detail in the upload dialog. Alternately, you may create custom models in a third party program and upload them into the four level of detail slots.

How do I test my model on ADITI (test grid) and upload it with the same settings on AGNI (main grid)?

Second Life saves your model upload parameters; when you upload a model on the Aditi test grid, you can upload it again on the main Second Life grid without needing to re-set all the parameters for the model.

Important: Make sure to double-check your parameters before uploading! We cannot refund Linden dollars lost in erroneous uploads.

I'm uploading a rigged mesh (animated mesh to be worn on the avatar) and...

Please create a thread on our mesh forum and tag it with [UPLOAD]. We're working on creating an upload troubleshooting page, which will help us answer questions in the future.

For general information on how to upload a rigged mesh, see Uploading and wearing a rigged mesh.

What is one example of how land impact calculations work to my benefit when compared to prim count?

Since physics is now calculated separately from streaming or server weight, you can simplify the physics weight of an old prim-based vehicle to something less than 32, allowing you to add more than 32 prims of visual detail without compromising the vehicle's physics performance or vehicle status.

Avatars and clothing have no land impact limits. What numbers should I aim for?

There are a few options for determining how much impact your attachments have:

• Turn on wireframe mode and take a look at your attachments. If they still look solid, it is likely that they contain more triangles than are necessary and are incurring too much streaming cost on the people around you. You can turn on wireframe mode in the Develop menu by choosing Develop > Rendering > Wireframe.
• Turn on Avatar Rendering Cost to see the overall impact of your avatar. ARC uses a different rating system than land impact; for more information on Avatar Rendering cost, see Avatar Rendering Cost.