In my Root Layer I have the Meters Per Unit set to 0.3048
However, when add new shapes to the scene they do not obey the MPU.
Am I misunderstanding how MPU is supposed to work?
Thanks.
my understanding is the MPU determines the scale of the scene. different OV apps may have the default set differently, but can be changed on the fly. for example, if MPU of your root layer is set to 1.0, the scene units becomes meters; conversely, if it’s at 0.01, it’s in centermeters. the unit of your scene can also be seen under the gimbal gizmo in the lower left hand corner of your viewport:
that said, if you were to bring a USD stage that’s in centermeters into another stage that’s in meters, there’s a conversion that takes place automatically thanks to another extension - the metric assembler ( Metrics Assembler — Omniverse Extensions latest documentation (nvidia.com))
if you find yourself using one specific unit as opposed to another and don’t want to keep switching it through the root layer property, you can set it in the preference of the app moving forward. i believe this preference will not alter the scene scale of the stage you may have currently open; it only affects the scene scale if you were to create new scene.
i am sure the mod will help clarify that further for you.
Can you clarify about “shapes”. You are referring to other cad files ? New objects ? When you say they are not obeying, you mean they come in at the wrong scale ?
I am not able to reproduce the issue that I was experiencing yesterday. However, I do have a further question drawing shapes in Omniverse USD Create. See my question below.
If I create a “new stage” in USD Composer and do the following:
- Open layer tab
- Click on root layer
- Change MPU to 0.3048 for feet
- Create a cube
- Measure the cube
- Notice how cube is 3.28 feet and the transform scale is 1
Shouldn’t the cube be 1-foot if the MPU is set to 0.3048?
Two things. First, in the program there are “shapes” and then there are “meshes”. They look the same but are very different. Do not use Shapes. Use Meshes.
So if you want a cube, create a mesh cube.
Second the 3.28 makes sense because it is creating a 1m cube.
Can I ask what kind of scene you are building that you need the scale to be in feet ? Normally you would be bringing in your CAD files from other software and we convert the scale correctly.
Sorry, I was using meshes (not shapes) and using the wrong terminology. I am new to graphics design, and all this is very new to me. Thanks for understanding.
Wouldn’t it be reasonable to expect Omniverse to create a mesh to the units provided in the MPU? Or does Omniverse only create items using meters regardless of the specified MPU?
We are evaluating how practical it is to directly create digital twins in the Omniverse using USD Create. With that said, we are accustomed to the imperial system, so inches and feet make more sense. We understand these items can be created using CAD and other design software.
Thanks.
USD Composer is NOT designed to create digital twins inside the application. It would be impossible. It has no modeling capabilities at all. It is designed that way on purpose. It is not a design program, or a CAD program. It is simulation and rendering program for assets already created in other applications.
The industrial design and digital twin world all use Meters, so that is what we use. We do not do imperial.
Thank you for the clarification about using Omniverse directly for creating digital twins.
To expand on this conversation, it would be nice if NVIDIA could provide some tutorials and examples on how to create advanced digital twin in the Omniverse. We were at GTC, and we are impressed on what Omniverse can do, but there isn’t anything that provides a real-world tutorial on how to get from zero to hero using the Omniverse. Does that make sense?
Thanks.
Well it starts with your super accurate CAD data outside of Omniverse. 90% of digital twin, is the cad data from Revit or process simulate or Siemens etc.
We don’t create data for digital twins. We just make it possible to collate and view it.
The Meters Per Unit (MPU) in the Root Layer sets the scale for the entire scene, but it won’t directly change the size of new objects you add.
Here’s the fix:
1- Add your new shape.
2- Go to the object properties (press “N” on your keyboard).
3- Look for the dimensions (X, Y, Z) and scale them by the desired factor (in your case, divide by 3.048 to get meters).
4- Save your startup file (File > Defaults > Save Startup File) so new objects inherit the MPU from now on.