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PictoBlox Extension

AprilTags Intellio Vision

April Tags intellio vision Extension
Extension Description
Learn how to use the PictoBlox AprilTags Extension with Quarky Intellio to detect tags, identify IDs, measure distance and orientation, track multiple tags, and build autonomous navigation projects in Upload Mode.
  • STEMpedia-Rocket-800x800 Available in: Block Coding
  • STEMpedia-Rocket-800x800 Mode: Upload Mode
  • STEMpedia-Rocket-800x800 WiFi Required: Yes
  • STEMpedia-Rocket-800x800 Compatible Hardware in Block Coding: Quarky Intellio
  • STEMpedia-Rocket-800x800 Compatible Hardware in Python: Not Applicable
  • STEMpedia-Rocket-800x800 Object Declaration in Python: NA
  • STEMpedia-Rocket-800x800 Extension Catergory:

Introduction

The AprilTags Extension (Intellio Vision) enables Quarky Intellio to detect and track AprilTags using its onboard camera.

Image capture, processing, and AprilTag detection are performed directly on Intellio after the programme is uploaded. This allows projects to run independently without continuously processing the camera feed through PictoBlox.

The extension provides access to:

  • Tag ID
  • Horizontal and vertical position
  • Bounding-box width and height
  • Two-dimensional rotation
  • Detection confidence
  • Three-dimensional position
  • Distance from the camera
  • Yaw, pitch, and roll
  • Number of tags detected
  • Multiple instances of the same tag ID

It also supports live camera display and rotated bounding boxes on a connected TFT screen for visualisation and debugging.

Important: This extension is specifically designed for Quarky Intellio in Upload Mode. The separate universal AprilTag extension should be used for Stage Mode projects.

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 work with 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: Switch the project from Stage Mode to Upload Mode.

change stage mode to upload mode in pictoblox

The Intellio Vision AprilTag blocks remain unavailable or greyed out in Stage Mode because this extension operates only in Upload Mode.

Step 4: Add the Extension

Click Add Extension from the Blocks Palette.

Search for and select: AprilTags Extension (Intellio Vision)

Select april tag intellio vision extension

The extension can be identified by the Intellio-specific name and icon.

Step 5: Open the AprilTags Blocks

The blocks will now appear under the AprilTags category in the Blocks Palette.

AprilTags Extension Blocks

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.
Read More

PictoBlox Blocks

This block initializes AprilTag detection and sets the AprilTag family and camera resolution.
This block controls the balance between detection accuracy and processing speed.
This block turns extra edge precision on or off to improve AprilTag boundary and corner detection accuracy.
This block turns the camera feed on or off on the TFT display.
This block shows or hides the AprilTag bounding box on the TFT display.
This block sets the physical side length of the printed AprilTag.
This block sets the minimum confidence required before a detection is accepted.
This block analyses the image from the Intellio onboard camera to detect AprilTags.
This block returns the total number of AprilTags detected in the analysed camera image.
This block checks whether the specified AprilTag ID is detected in the analysed camera image.
This Boolean block checks whether a particular AprilTag ID was detected in the latest image analysis.
This block returns how many detected tags have the selected ID.
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