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Exporting a geometry suitable for DRTF generation from AutoCAD

AutoCAD is one of many CAD modeling tools used to build geometry assemblies made of different parts. Other tools include Rhinoceros, SolidWorks, Autodesk Fusion and CATIA. This tutorial shows how to use AutoCAD to export a CAD file to a DXF file that you can import as a device geometry in the SDK.

Although you can create a mesh primitive with the shape of a cylinder, this tutorial shows how to mesh a 3D solid created from a curve and an extrusion.

Key steps:

  1. Create a simple shape like a cylinder in AutoCAD
  2. Convert the solid to surfaces
  3. Convert the surfaces to mesh
  4. Import the DXF into the SDK

Create a simple shape like a cylinder in AutoCAD​

Creating a circle in AutoCAD

From the Home tab on the top left, select Circle. Pick or type the origin point 0,0,0.

Set a radius by typing it or picking a point, for example 0.04. The unit is meters.

Extruding a circle in AutoCAD

Next, select the Circle and type the command EXTRUDE. Specify the height along the z direction, for example 8 cm as 0.08 meters.

An extruded cylinder in AutoCAD

Changing the view angle using the navigator and switching the visibility to Hidden reveals the cylinder as a 3D Solid, with a series of handles that allow its modification. The geometry is listed as 3D Solid in the property inspector on the right.

Convert the solid to surfaces​

Convert the solid to surfaces using the command CONVTOSURFACE.

3D Solid converted to Surface

Convert the surfaces to mesh​

Use MESHOPTIONS to transform the surface into a mesh.

Mesh Tessellation Options window

In this window, set the resolution of your mesh. Select Meshing Primitive Solids to optimize the meshing for primitives such as a cylinder. Select the mesh type Triangle, as shown in the picture below.

Setting Mesh options to primitive solids.

You can also edit the maximum edge length when generating new faces. AutoCAD then tries to keep every element edge below that limit. The picture below shows how setting a limit of 5 mm creates very small faces. In this case, deselect the Meshing Primitive Solids checkbox and the box that applies smoothing in the lower panel.

Mesh with a 5 mm maximum edge length

Import the DXF into the SDK​

The final step consists of saving the geometry as a DXF file and importing it into the SDK.

Set up the project and the device properties:

from treble_tsdk import treble

tsdk = treble.TSDK()
project = tsdk.get_or_create_project("test-speaker")

device_name = "SmartSpeaker"
device_model_path = "mesh_examples/SmartSpeaker.dxf"
device_microphone_placements = [  # speaker microphones
    treble.Point3d(0.00, 0.00, 0.08),
    treble.Point3d(0.01, 0.00, 0.08),
    treble.Point3d(-0.01, 0.00, 0.08),
]

frequency = 12000
ambisonics_order = 32
freefield_model_name = "Smart_speaker_model"
freefield_simulation_name = "Smart_speaker_sim"

Prepare the free field simulation:

ff_def = project.setup_drtf_simulation(
    simulation_name=freefield_simulation_name,
    freefield_model_name=freefield_model_name,
    device_geometry=device_model_path,
    device_microphone_placements=device_microphone_placements,
    frequency=frequency,
    ambisonics_order=ambisonics_order,
)
ff_def.plot()

Add the free field definition and start the simulation:

ff_sim = project.add_simulation(ff_def)
ff_sim.start()

Add the device to the organization library:

results_dir = "<results_directory>"
ff_res = ff_sim.get_results_object(results_directory=results_dir)

device_def = ff_res.create_drtf(device_name=device_name, ambisonics_order=ambisonics_order)
device = tsdk.device_library.add_device(device_definition=device_def)

device.plot()

The speaker file exported from AutoCAD is available as a .dxf file in the bundle below:

Click to download mesh files
info

This guide has been tested with AutoCAD version 2026.