Use webcam to detect and visualize hands (3D World space)

This example demonstrates how to load and display camera feed in a Unity scene with a WebcamSource and an ImageView, implement hand tracking with the HandTracker, and use the HandManager to render detected fingers in 3D world space.

Step 1: Create a Unity scene

Open the Unity Project you created in the Installation section.

Right-click on the Assets folder and select Create > Scene.

Type the scene's name. In this example, we'll use the name WebcamDemo3D.

After the scene is created, right-click on the scene and select GameObject > UI > Canvas.

Navigate to the LightBuzz Prefabs folder at Assets\LightBuzz Hand Tracking\Runtime\Prefabs.

For this example, you'll need the ImageView, WebcamSource and HandManager prefabs.

Drag and drop the ImageView and WebcamSource prefabs into the Canvas.

Drag and drop the HandManager prefab on the Hierarchy pane (but not into the Canvas).

Then, right-click on the Hierarchy pane and select Create Empty.

Give a name to the new component. In this example, we'll use the name Demo.

Then, go to the Inspector pane and select Add Component. In the search bar, type new and select the New script option.

Type the script's name and select Create and Add. For this example, we'll use the name WebcamDemo3D.

Step 2: Initialize the visual components

Double-click on the newly created MonoBehaviour script and import the necessary namespaces.

using LightBuzz.HandTracking;
using System.Collections.Generic;
using UnityEngine;

For this example, we'll need a WebcamSource to get the frames, an ImageView to draw camera texture and a HandManager to visualize the detected hands.

[SerializeField] private ImageView _image;
[SerializeField] private WebcamSource _webcam;
[SerializeField] private HandManager _handManager;

After adding the serialized fields, go to the Unity Editor to connect these fields with the Demo component.

At the Inspector pane, select the round button next to each SerializeField.

Then, at the Scene tab, select the corresponding prefab. For example, for the Image field, select the ImageView prefab.

When all fields are connected, the result should resemble the following image.

Then, select the HandManager prefab. Connect the Image field to the ImageView prefab and uncheck the Is 2D option.

After connecting all the fields, navigate to the Canvas to set the render options.

Change the Render Mode to Screen Space - Camera.

Then, set the Main Camera, from the Scene tab, as the Render Camera.

When all the render options are set, the result should look like the following image.

Step 3: Adjust Scene components

To display the hand detections in the 3D world space we need to adjust the ImageView.

Navigate to the ImageView prefab, under the Canvas, go to the Aspect Ratio Fitter section and change Aspect Mode to None.

Then, go to the Rect Transform section of the ImageView prefab and click on the blue cross to open the Anchor Presets.

Select the middle and center option (the one that looks like a target).

Then, change the Width to 400, the Height to 200 and the Pos X to -600.

For a proper view, navigate to the Main Camera component and set the Y Position to 0, since the 3D coordinates of the hands are estimated relative to the cartesian origin point. Also, set the Z Position to -1 to move the camera farther from the hands.

Finally, return to the MonoBehaviour script and instantiate a HandTracker to detect hands.

HandTracker _handTracker = new HandTracker();

Step 4: Open the webcam

Open the webcam to get the live feed.

_webcam.Open();

Step 5: Get the live feed

Check that the camera is open and available for capturing video.

if (!_webcam.IsOpen) return;

Load the new frame from the _webcam object onto the ImageView to show the live feed to your users.

_image.Load(_webcam);

Step 6: Detect hands

Pass the Texture2D object from the camera frame to the HandTracker for processing.

List<Hand> hands = _handTracker.Load(_image.Texture);

The HandTracker will analyze the texture and detect any hands present in the image.

Step 7: Visualize the hands

To display the detected hands in 3D world space, first sort the hands by position X.

hands.Sort((h1, h2) => 
    h1[FingerJointType.Root].Position2D.x.CompareTo(
        h2[FingerJointType.Root].Position2D.x));

In this example, each new hand will be positioned 25 cm away from the previous one.

List<Vector3> offsets = new List<Vector3>();
float offset_x = 0f;
float step = 0.25f;

foreach (Hand hand in hands)
{
    offsets.Add(new Vector3(offset_x, 0f, 0f));
    offset_x += step;
}

Then, simply pass the hand detections and the offsets to the HandManager. It will manage the rendering and updates required to accurately depict the hands in 3D world space based on the detection data provided.

_handManager.Load(hands, offsets);

Step 8: Release the resources

Close the webcam to stop the live feed, preventing further video capture.

_webcam.Close();

Dispose of the HandTracker object to ensure that all associated resources are released.

_handTracker.Dispose();

Full example code

Here is the full example code that has the same functionality as the Hand Tracking Unity plugin LightBuzz_Hand_Tracking_3D sample.

using LightBuzz.HandTracking;
using System.Collections.Generic;
using UnityEngine;

public class WebcamDemo3D : MonoBehaviour
{
    [SerializeField] private ImageView _image;
    [SerializeField] private WebcamSource _webcam;
    [SerializeField] private HandManager _handManager;
    
    private readonly HandTracker _handTracker = new HandTracker();

    private void Start()
    {
        _webcam.Open();
    }

    private void OnDestroy()
    {
        _webcam.Close();
        _handTracker.Dispose();
    }

    private void Update()
    {
        if (!_webcam.IsOpen) return;

        // 1. Draw the camera texture.
        _image.Load(_webcam);

        // 2. Detect hands in the camera texture.
        List<Hand> hands = _handTracker.Load(_image.Texture);
        
        // 3. Sort hands by position X.
        hands.Sort((h1, h2) => 
            h1[FingerJointType.Root].Position2D.x.CompareTo(
                h2[FingerJointType.Root].Position2D.x));

        // 4. Add offset to show all detected hands.
        List<Vector3> offsets = new List<Vector3>();
        float offset_x = 0f;
        float step = 0.25f;

        foreach (Hand hand in hands)
        {
            offsets.Add(new Vector3(offset_x, 0f, 0f));
            offset_x += step;
        }

        // 5. Visualize the hands on a Canvas.
        _handManager.Load(hands, offsets);
    }
}

By following these steps, you will be able to load the camera feed into your application, detect hands in real time, and finally, render these detections in 3D world space.