# SoftBank Robotics documentation What's new in NAOqi 2.8?

# ALLandMarkDetection API

NAOqi Vision - Overview | API | Tutorials

Namespace : AL

    #include <alproxies/allandmarkdetectionproxy.h>

## Method list

class `ALLandMarkDetectionProxy`

- As any module, this module inherits methods from ALModule API.
- It also inherits methods from ALExtractor API.

## Event list

- `LandmarkDetected()`

## Events

Event: `"LandmarkDetected"`
callback(std::string eventName, AL::ALValue value, std::string subscriberIdentifier)

  Raised when one or several landmarks are currently being detected.

  Parameters: | eventName (std::string) – “LandmarkDetected” value – Informations related to the detected landmarks. Further details below. subscriberIdentifier (std::string) –

## LandMarkDetected Value Structure

The output ALValue is organized as follows:

### ALLandMarkDetection

    ALLandMarkDetection {
      TimeStamp,
      MarkInfo[N],
      CameraPoseInFrameTorso,
      CameraPoseInFrameRobot,
      CurrentCameraName
    }

with as many mark_info tags as marks currently detected.

### TimeStamp

This field is the time stamp of the image that was used to perform the detection.

    TimeStamp {
      TimeStamp_Seconds,
      Timestamp_Microseconds
    }

### MarkInfo

For each detected mark, we have one MarkInfo field:

    MarkInfo {
      ShapeInfo,
      MarkID
    }

#### ShapeInfo

    ShapeInfo {
      1,
      alpha,
      beta,
      sizeX,
      sizeY,
      heading
    }

- alpha and beta represent the location of the NaoMark’s center in terms of camera angles in radian.
- sizeX and sizeY are the mark’s size in camera angles.
- the heading angle describes how the Naomark is oriented about the vertical axis with regards to the robot’s head.

#### MarkID

is the number written on the Naomark and which corresponds to its pattern.

### CameraPoseInFrameTorso

Position6D of the camera at the time the image was taken, in FRAME_TORSO.

### CameraPoseInFrameRobot

Position6D of the camera at the time the image was taken, in FRAME_ROBOT.

### CurrentCameraName

Name of the camera that was used to take the image (“CameraTop”, or “CameraBottom”).

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