src/qcam/assets/feathericons/github.svg


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# SPDX-License-Identifier: LGPL-2.1-or-later
#
# Copyright (C) 2019, Google Inc.
#
%YAML 1.1
---
vendor: libcamera
controls:
  - Location:
      type: int32_t
      description: |
        Camera mounting location
      enum:
        - name: CameraLocationFront
          value: 0
          description: |
            The camera is mounted on the front side of the device, facing the
            user
        - name: CameraLocationBack
          value: 1
          description: |
            The camera is mounted on the back side of the device, facing away
            from the user
        - name: CameraLocationExternal
          value: 2
          description: |
            The camera is attached to the device in a way that allows it to
            be moved freely

  - Rotation:
      type: int32_t
      description: |
        The camera physical mounting rotation. It is expressed as the angular
        difference in degrees between two reference systems, one relative to the
        camera module, and one defined on the external world scene to be
        captured when projected on the image sensor pixel array.

        A camera sensor has a 2-dimensional reference system 'Rc' defined by
        its pixel array read-out order. The origin is set to the first pixel
        being read out, the X-axis points along the column read-out direction
        towards the last columns, and the Y-axis along the row read-out
        direction towards the last row.

        A typical example for a sensor with a 2592x1944 pixel array matrix
        observed from the front is

                    2591       X-axis          0
                      <------------------------+ 0
                      .......... ... ..........!
                      .......... ... ..........! Y-axis
                                 ...           !
                      .......... ... ..........!
                      .......... ... ..........! 1943
                                               V


        The external world scene reference system 'Rs' is a 2-dimensional
        reference system on the focal plane of the camera module. The origin is
        placed on the top-left corner of the visible scene, the X-axis points
        towards the right, and the Y-axis points towards the bottom of the
        scene. The top, bottom, left and right directions are intentionally not
        defined and depend on the environment in which the camera is used.

        A typical example of a (very common) picture of a shark swimming from
        left to right, as seen from the camera, is

                     0               X-axis
                   0 +------------------------------------->
                     !
                     !
                     !
                     !           |\____)\___
                     !           ) _____  __`<
                     !           |/     )/
                     !
                     !
                     !
                     V
                   Y-axis

        With the reference system 'Rs' placed on the camera focal plane.

                                        ¸.·˙!
                                    ¸.·˙    !
                        _       ¸.·˙        !
                     +-/ \-+¸.·˙            !
                     | (o) |                ! Camera focal plane
                     +-----+˙·.¸            !
                                ˙·.¸        !
                                    ˙·.¸    !
                                        ˙·.¸!

        When projected on the sensor's pixel array, the image and the associated
        reference system 'Rs' are typically (but not always) inverted, due to
        the camera module's lens optical inversion effect.

        Assuming the above represented scene of the swimming shark, the lens
        inversion projects the scene and its reference system onto the sensor
        pixel array, seen from the front of the camera sensor, as follow

                  Y-axis
                     ^
                     !
                     !
                     !
                     !            |\_____)\__
                     !            ) ____  ___.<
                     !            |/    )/
                     !
                     !
                     !
                   0 +------------------------------------->
                     0               X-axis

        Note the shark being upside-down.

        The resulting projected reference system is named 'Rp'.

        The camera rotation property is then defined as the angular difference
        in the counter-clockwise direction between the camera reference system
        'Rc' and the projected scene reference system 'Rp'. It is expressed in
        degrees as a number in the range [0, 360[.

        Examples

        0 degrees camera rotation


                          Y-Rp
                           ^
                    Y-Rc   !
                     ^     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !     !
                     !   0 +------------------------------------->