Usage

The user can then import the DGN file into Omniverse via two workflows: via File Menu Window or via the Content Window.

How to Import and Convert Files

File -> Import

1. To import a CAD file into Omniverse, choose Import in the File menu.

2. The user should now see a window similar to a file manager. The user needs to then select a DGN file for conversion from this window.

3. Refer to Converter Options section for more information on conversion settings.

Import through the Content Window

1. By default the Content window is located at the bottom of the Omniverse App. To convert a CAD file to USD, select the file in the Content window and choose Convert to USD in the context menu with right mouse button.

2. Browse to the location of your file or files, select them, and right-click, and select Convert to USD in the Context menu.

3. The Converter Options dialog window will appear, modify any options as needed, and click Convert.

Note: The Content Window tab provides a file browser interface for navigating and managing files. If it is not shown, go to the Menu toolbar, select “Window”, and then select “Content”.

Converter Options

The DGN converter provides several options to control how files are converted:

Stage Metrics Options

These options modify the stage’s metersPerUnit and upAxis settings, applying relevant transformations to maintain proper world space units.

Option	Description
Override Up-Axis	Override the stage’s up-axis to Y-up, Z-up, or use converter default
Meters Per Unit	Set the stage’s meters per unit metric (0.0 retains original conversion value)

Conversion Options

Option	Description
Convert Curves	If enabled, curves from the source file (Lines, Linestrings, Arcs, Ellipses, etc.) are converted to USD BasisCurves. If disabled, these elements are ignored.
Convert Visible Only	If enabled, skips hidden elements. If disabled, converts hidden elements but sets them to invisible.
Instancing Style	When instancing is enabled (Instancing Style set to “Scenegraph Instancing”), the DGN converter creates USD instancing structures to efficiently represent Shared Cell References from the DGN file. For detailed information about how instancing is authored, why class prims are used for prototypes, and how to work with prototype prims for debugging, see Instancing in USD.

Material Options

Material Type	Description
None	No materials generated
Preview Surface	Default option, creates a simple preview surface material compatible with Universal renderer
OmniPBR	Creates a physically based material compatible for RTX and Universal renderers

Note: For more information about materials, see Materials Templates documentation

Advanced Options

Option	Description
Generate Projection UVs	When UV texture coordinates are missing, uses Scene Optimizer Kit Extension to generate texture coordinates for meshes. Uses default values as described in the Generate Projection UVs documentation.
Convert Element ID	When enabled, DGN element IDs are converted to custom USD attributes or primvars
Merge Meshes	When enabled, meshes sharing the same level, color, and element type are merged for optimization. When disabled, mesh merging is skipped.
Merge Curves	When enabled, curves are merged for optimization
Use Materials	When enabled, materials from the source file are converted to USD materials. When disabled, converter creates materials with the color set as an attribute or converts colors to USD displayColor primvars.
Triangulate	When enabled, all polygons are triangulated during conversion
Apply Global Origin	When enabled, applies the global origin transformation to the converted scene. When disabled, the value is stored as an attribute but the Model has no transform applied.
Fallback Curve Width	Default curve width when not specified in source. Set to -1 to use source default.
Level Filter Style	Controls how filtered levels are handled. Options: None (no filtering), Omit (skip filtered levels), Hide (convert but hide), Deactivate (convert but deactivate)
Geometry Attribute Style	Controls how DGN geometry attributes are authored to USD. Options: None (don’t author attributes), Attribute (default, author as a custom attribute), Primvar (author as a constant primvar)
Merged Attribute Style	Sets the attribute style for merged geometry. Options: None (no attributes on merged geometry), Primvar (store attributes as primvars), Subset (store attributes using geometry subsets)
Verbose Logging	When enabled, verbose logging will be reported to omni logs and the console during conversion. Useful for debugging conversion issues or when detailed conversion reports are required.

Tessellation Control

Tessellation options control mesh accuracy versus performance. These settings determine how surfaces are converted into triangular meshes.

Surface Tolerance

The surface tolerance setting controls mesh accuracy versus performance:

Tolerance Range	Use Case	Result
Low (0.001 - 0.01)	High precision needs	More detailed mesh, larger files, slower processing
High (0.1 - 1.0)	Visualization (recommended)	Less detailed mesh, smaller files, faster processing

Default value is 0.2 for balanced performance and quality. Setting to 0 automatically uses 2.5% of model’s bounding box diagonal.

Note: For detailed information about tessellation, see Open Design Alliance’s blog post

Additional Tessellation Options

Option	Description	Default
Normal Tolerance	Maximum angle (in degrees) between adjacent face normals. Smaller values produce smoother surfaces with more triangles. Controls tessellation quality of circular surfaces (Cone, Torus, Sphere, Cylinder). Measured in degrees, determines quantity of mesh cells (360/NormalTolerance).	15.0
Between Knots	Number of points to add between knots when tessellating curves. For NURB surfaces, contains number of additional isolines between knots.	2
Grid Aspect Ratio	Grid aspect ratio for tessellation. Set to 0 for automatic calculation.	0.0
Max Facet Edge Length	Maximum facet edge length for tessellation. Set to 0 for no limit.	0.0
Max Grid Lines	Maximum number of grid lines for tessellation.	10000
Points Per Edge	Points per edge for curve tessellation. Set to 0 for automatic calculation.	0

Output Options

Option	Description
Path	Destination folder for converted USD (defaults to source location)
Scene Optimizer Config	Path to Scene Optimizer JSON config file or JSON string for predefined optimization stack. See Scene Optimizer Service documentation.

Getting Help

• Omniverse Enterprise Customer Support Services.

• The Developer Community can also ask questions or report issues on Omniverse Developer forums.