Overview

Calibrate Camera is designed to adjust the camera view to match real-world distances accurately. This functionality is useful for applications requiring precise distance measurements from video data. By ensuring the camera's view is correctly calibrated, users can rely on the accuracy of distance measurements within the video feed, enhancing the application's reliability and effectiveness.

The output of this node is used by Speed Estimation node.

Inputs & Outputs

Inputs : 1, Media Format : Raw Video
Outputs : 1, Media Format: Raw Video
Output Metadata : Presence Information

Properties

Property	Description	Type	Default	Required
`roi_labels`	Calibration square labels	`string`	`calibration`	No
`rois`	Draw a 4-point square ROI on the ground, such that it's length in real world is equal to calibration Length specified below. Conditional on `roi_labels`. Format: comma-separated normalized `x,y` coordinate pairs; separate multiple polygons with semicolons (for example, `0.1,0.1,0.9,0.1,0.9,0.9`).	`string`	`0.25,0.25,0.25,0.75,0.75,0.75,0.75,0.25`	No
`roi_size`	Real-world length of the square. Range: minimum `1`, maximum `100.0`. Step: `1`.	`integer`	`5`	Yes
`roi_size_units`	Length calibration unit. Options: Foot (`ft`); Meter (`m`).	`enum`	`ft`	No
`display_roi`	Display calibration grid?	`bool`	`false`	No

Output Metadata

The fields below are declared by this node's metadata schema; the JSON values are representative examples.

Path	Type	Description
`nodes.<node_id>.homography`	`array`	Two-dimensional array containing the camera calibration homography matrix.
`nodes.<node_id>.homography_units`	`string`	Measurement units used by the calibration homography.
`nodes.<node_id>.type`	`string`	Identifies the node type that produced this metadata.

JSON example

{
  "nodes": {
    "calibrate_camera1": {
      "homography": [],
      "homography_units": "value",
      "type": "calibrate_camera"
    }
  }
}