Detect and visualize hands from a Sprite

An example on how to detect and visualize hands from a Sprite.

This example demonstrates how to load and display image sprites in a Unity scene with an ImageView, implement hand tracking with the HandTracker, and use the HandManager to render detected fingers on a 2D canvas.

This is a code walkthrough of the LightBuzz_Hand_Tracking_Picture Hand Tracking Unity plugin sample. The plugin includes the no-code demo that has the same functionality.

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.

Create new scene

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

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

Add a Canvas

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

LightBuzz Prefabs

For this example, drag and drop the ImageView and HandManager prefabs into the Canvas.

Add prefabs

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

Create empty component

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.

Add script

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

Create script

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 Spriteto load an image, an ImageView to draw its texture and a HandManager to visualize the detected hands.

[SerializeField] private ImageView _image;
[SerializeField] private HandManager _handManager;
[SerializeField] private Sprite _sprite;

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.

Seriaze fileds

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

Connect prefab

The Sprite field should connect to an image sprite. You can either use the demo image sprite lightbuzz-hand-tracking.png included in the Assets/LightBuzz Hand Tracking/Runtime/Media folder or create your own image sprite.

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

Connected serialize fields

Then, select the HandManager prefab, under the Canvas, and connect the Image field to the ImageView prefab.

Connect field to HandManager

Make sure the Is 2D option is selected to see the hand tracking detections in the 2D space. If the option is not checked, detections are displayed in the 3D world space.

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

Change the Render Mode to Screen Space - Camera.

Change Render Mode

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

Select Render Camera

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

Render settings

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

HandTracker _handTracker = new HandTracker();

Step 3: Load the image

Create a Texture2D object with the Sprite's texture.

Texture2D texture = _sprite.texture;

Load the Texture2D object onto the ImageView to show the image.

_image.Load(texture);

Step 4: Detect hands

Pass the texture created in Step 3 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 5: Visualize the hands

To display the detected hands on a 2D canvas, simply pass the detections to the HandManager. It will manage the rendering and updates required to accurately depict the hands on the canvas based on the detection data provided.

_handManager.Load(hands);

Steps 3 through 5 are incorporated into the Start() method.

Step 6: Release the resources

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

_handTracker.Dispose();

In this example, the resources are released in the OnDestroy() method. Alternatively, you could do that with the click of a button or in the OnApplicationQuit() method.

Full example code

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

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

public class PictureDemo : MonoBehaviour
{
    [SerializeField] private ImageView _image;
    [SerializeField] private HandManager _handManager;
    [SerializeField] private Sprite _sprite;

    private readonly HandTracker _handTracker = new HandTracker();

    private void Start()
    {
        Texture2D texture = _sprite.texture;

        _image.Load(texture);

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

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

By following these steps, you will be able to load a Sprite into your application, detect hands, and finally, render these detections on a 2D canvas.