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  • AprilTag
  • Inputs and Outputs
  • Limitations
  • Examples of functionality
  • Reference

AprilTag

AprilTag node takes ImgFrame as input and outputs detected AprilTag markers (AprilTags message). It's based on the AprilRobotics/apriltag repository, and runs optimized detection algorithms on the CPU (on RVC4 octacore itself, or on the host when using RVC2-based devices).AprilTag marker is a visual fiducial marker <https://en.wikipedia.org/wiki/Fiducial_marker>__, so it's similar to ArUco, ARTag and ARToolKit markers.

Inputs and Outputs

Command Line
1/
2                 ┌───────────────────┐
3  inputImage     │                   │passthroughInputImage
4  ──────────────►│-------------------│───────────►
5                 │                   │         out
6                 │     AprilTag      ├───────────►
7  inputConfig    │                   │   outConfig
8  ──────────────►│-------------------│───────────►
9                 │                   │
10                 └───────────────────┘

Limitations

RVC2
RVC4

RVC2

On the RVC2 devices, the AprilTag node runs on the host computer, so the performance will be limited by the host CPU.

Examples of functionality

Reference

class

depthai.node.AprilTag(depthai.Node)

method
setWaitForConfigInput(self, wait: bool)
Specify whether or not wait until configuration message arrives to inputConfig Input.  Parameter ``wait``:     True to wait for configuration message, false otherwise.
property
initialConfig
Initial config to use when calculating spatial location data.
property
inputConfig
Input AprilTagConfig message with ability to modify parameters in runtime. Default queue is non-blocking with size 4.
property
inputImage
Input message with depth data used to retrieve spatial information about detected object. Default queue is non-blocking with size 4.
property
out
Outputs AprilTags message that carries spatial location results.
property
passthroughInputImage
Passthrough message on which the calculation was performed. Suitable for when input queue is set to non-blocking behavior.

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