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PictoBlox Extension

AprilTags (Beta)

AprilTag Extension
Extension Description
The AprilTags Extension enables PictoBlox to detect and identify AprilTags using a camera feed or stage image. It provides information such as tag ID, position, size, rotation, confidence, and optional 3D pose information.
  • STEMpedia-Rocket-800x800 Available in: Block Coding
  • STEMpedia-Rocket-800x800 Mode: Stage Mode
  • STEMpedia-Rocket-800x800 WiFi Required: No
  • STEMpedia-Rocket-800x800 Compatible Hardware in Block Coding: Not Applicable
  • STEMpedia-Rocket-800x800 Compatible Hardware in Python: Not Applicable
  • STEMpedia-Rocket-800x800 Object Declaration in Python: NA

Introduction

The AprilTags Extension (Beta) allows you to detect AprilTags using a camera and analyse the information associated with each detected tag.

AprilTags can be used as visual markers in projects where a computer needs to identify a specific location, object, or direction. Once a tag is detected, PictoBlox can provide information about its ID, position, size, rotation, confidence, and pose.

The extension can also display bounding boxes around detected tags, making it easier to understand and debug the detection process.

Important: This extension is specifically designed for Stage Mode projects in PictoBlox. It uses the camera feed or stage snapshots to detect and analyse AprilTags.

Initialise AprilTag and Camera Resolution

What Is an AprilTag?

An AprilTag is a machine-readable visual marker made from a black square border and a unique internal pattern.

It is similar to a QR code, but instead of storing information such as a website address, an AprilTag acts as a visual landmark for cameras and robots.

When Intellio detects an AprilTag, it can determine:

  • Which tag is visible
  • Where the tag is located in the camera frame
  • How far it is from the camera
  • Whether it is rotated
  • How the camera is positioned relative to it

This makes AprilTags useful for:

  • Robot navigation
  • Autonomous docking
  • Position correction
  • Location marking
  • Object identification
  • Multi-tag commands
  • Route planning
  • Camera alignment

Before You Begin

1. Download or update PictoBlox

Install the latest available version of PictoBlox before using the extension. Download PictoBlox

Note: Please wait for the new version of PictoBlox to be released before using this extension.

2. Update Quarky Intellio Firmware

The AprilTag detection model is included in the newer Intellio firmware. Please upload the latest firmware before running an AprilTag programme.

Older firmware may not support the required AprilTag functionality. Click here to learn How to update the firmware on Quarky Intellio?

3. Prepare the AprilTags
Use printed tags from one of the supported families:Make your own AprilTags PDF redirection

  • 16h5
  • 25h9
  • 36h11

The selected family in the programme must match the family of the printed tag. A tag from one family will not be detected when another family is selected during initialisation.

4. Prepare the Environment

For reliable detection:

  • Place tags on a flat surface.
  • Use clear, high-contrast printing.
  • Keep the complete black border visible.
  • Avoid folds, damage, and glossy lamination.
  • Use soft and even lighting.
  • Avoid strong reflections and shadows.
  • Keep the Intellio camera unobstructed.

AprilTags may be rotated at different angles and can still be detected. However, mirrored or flipped tag images should not be used.

Accessing the AprilTags Extension in PictoBlox

Step 1: Open PictoBlox and Select Block Coding.

Select Block Coding in Pictoblox

Step 2: Click Board and select Quarky Intellio.

Go to the Board and select Quarky Intellio

Step 3: Click Add Extension from the Blocks Palette.

Step 4: Search for and select AprilTags.

Select April Tags extnsion

The Intellio-specific name and icon can identify the extension.

Step 5: The AprilTags blocks will appear in the AprilTags category of the Blocks Palette.

april tags blocks in block pallete

Downloading AprilTag Markers

The extension includes an option to download printable AprilTag markers.

Make your own AprilTags PDF redirection

The provided PDF contains sample tags from the supported families, including tag IDs that can be used in the examples.

When printing:

  • Do not crop the black border.
  • Keep the marker square.
  • Avoid resizing the tag unevenly.
  • Measure the final printed size before setting the tag-size value.
  • Use non-reflective paper where possible.

Extension Workflow

AprilTags Extension Workflow

This structure makes the documentation more useful than simply listing the blocks: it explains what AprilTags are, how to configure detection, what each block does, what information is returned, and how that information can be used in a project.

Read More
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