Missing "Convex Decomposition" option for Mesh collision in Isaac Sim 5.1 GUI

[c00sm00s]

Describe the Issue:

I am trying to generate convex decomposition (V-HACD) for non-convex meshes (robot link parts in .stl/.obj format) in Isaac Sim 5.1. However, I cannot find the "Convex Decomposition" option in the expected UI locations.

Environment Info:

OS: Windows 11
Isaac Sim Version: 5.1.0 (GUI)
GPU: NVIDIA GeForce RTX 3050 Laptop
Driver Version: 595.79

Steps to Reproduce / What I've Tried:

1. Imported a .stl mesh into the Stage.
2. Selected the Mesh prim.
3. Right-clicked and navigated to Add -> Physics.

Problem: "Convex Decomposition" is NOT listed in the menu. Only standard options like Rigid Body, Collision, and Mass are visible.

I also checked the Physics top menu bar and could not find a dedicated V-HACD tool.

Specific Questions:

In Isaac Sim 5.1, has the V-HACD workflow moved to the Property Panel under Collision API -> Approximation?

If so, what are the steps to trigger the "Cooking" process to visualize the generated convex hulls?

Are there any specific Extensions (e.g., omni.physx.ui or others) that need to be manually enabled to expose V-HACD settings in this version?

[c00sm00s]

[d-kleine]

You would need to add a collider. Add the collider via the stage window (top right) by clicking on the part (in your case just the cylinder object) and Add -> Physics -> Colliders Presets (or via the viewport selecting the part directly, just like you did)

After that, go into the viewport (left side main window), you need to enable the visibility of colliders. For that, click in the viewport on the eye button and and "Show by type" -> Physics -> Colliders -> and select "Selected". Once enabled, this will show a red colored collision mesh around the selected part.

Then click on the object (either in the viewport or in the stage view) to select it. Now take a look into the properties view, scroll down to the "Physics" panel. There is an option "Collider" and a setting "Approximation", preset is "Convex Hull". Click on it and it should open a drop-down menu, where you can select also "Convex Decomposition".

Once select a different approximation method, you should see that the red mesh for the selected part looks slightly different, with convex decomposition a bit finer than convex hull.

(If you have added a collider on the selected part and the "Collider" option does not show up in the Properties' Physics panel even though you have added it, you need to jump to a different stage/part in the stage view and back onto the selected part. This is because the properties window for the part does not update by itself visually.)

[vick-yu]

d-kleine's answer covers this well. To add a bit more context:
 
In Isaac Sim 5.1, "Convex Decomposition" isn't a standalone menu action -- it's one of
several collision approximation types available after you've added a collider to a mesh.
 
The workflow is:

1. Select your mesh -> right-click -> Add -> Physics -> Colliders Presets
2. In the Properties panel (right side), scroll to Physics -> Collider ->
   Approximation dropdown
3. Switch from the default "Convex Hull" to "Convex Decomposition"
    
   The omni.convexdecomposition extension ships enabled by default -- no extra setup needed.
    
   For Python/scripting workflows, you can also set it programmatically:
    

from pxr import UsdPhysics, PhysxSchema
import omni.usd
 
stage = omni.usd.get_context().get_stage()
prim = stage.GetPrimAtPath("/World/YourMesh")
 
# Add collision API
UsdPhysics.CollisionAPI.Apply(prim)
mesh_collision = UsdPhysics.MeshCollisionAPI.Apply(prim)
mesh_collision.GetApproximationAttr().Set("convexDecomposition")

[c00sm00s]

Thank you all ，it works！