Camera pose tracking

Monitor and read camera poses from connected clients in real-time.

This example demonstrates how to track camera movements and handle multiple connected clients. Camera pose tracking is essential for applications like telepresence, collaborative visualization, or recording user viewpoints for replay.

Key features:

• viser.ViserServer.on_client_connect() for detecting new client connections

• viser.CameraHandle.on_update() for real-time camera movement callbacks

• viser.CameraHandle.wxyz and viser.CameraHandle.position for pose data

• viser.CameraHandle.fov and viser.CameraHandle.aspect for camera parameters

The example shows how to access camera intrinsics (FOV, aspect ratio, canvas size) and extrinsics (position, orientation) from each connected client, enabling synchronized multi-user experiences or camera-based interactions.

Source: examples/03_interaction/03_camera_poses.py

Code

import time

import viser

server = viser.ViserServer()
server.scene.world_axes.visible = True


@server.on_client_connect
def _(client: viser.ClientHandle) -> None:
    print("new client!")

    # This will run whenever we get a new camera!
    @client.camera.on_update
    def _(_: viser.CameraHandle) -> None:
        print(f"New camera on client {client.client_id}!")

    # Show the client ID in the GUI.
    gui_info = client.gui.add_text("Client ID", initial_value=str(client.client_id))
    gui_info.disabled = True


while True:
    # Get all currently connected clients.
    clients = server.get_clients()
    print("Connected client IDs", clients.keys())

    for id, client in clients.items():
        print(f"Camera pose for client {id}")
        print(f"\twxyz: {client.camera.wxyz}")
        print(f"\tposition: {client.camera.position}")
        print(f"\tfov: {client.camera.fov}")
        print(f"\taspect: {client.camera.aspect}")
        print(f"\tlast update: {client.camera.update_timestamp}")
        print(
            f"\tcanvas size: {client.camera.image_width}x{client.camera.image_height}"
        )

    time.sleep(2.0)