Orthority interior parameters

This is the native Orthority format for frame camera interior parameters. It is a YAML file containing a nested dictionary based on the OpenDroneMap / OpenSfM cameras.json format. The root level consists of one or more camera ID keys and the corresponding parameter dictionary values. Parameter dictionaries define parameter name - value pairs for a camera. The basic layout is:

camera 1 ID:
    # camera 1 parameters:
    name 1: value 1
    # ...
    name N: value N
# ...
camera N ID:
    # camera N parameters:
    name 1: value 1
    # ...
    name N: value N

Camera IDs can be used in exterior parameters to refer to a specific camera in multi-camera setups (e.g. with the camera field in CSV and Orthority exterior parameter files), and should be unique. Parameter names and value descriptions are as follows:

Name	Value
type	Camera type (pinhole, brown, fisheye, opencv).
im_size	Image [width, height] in pixels.
focal_len	Focal length(s) with the same units/scale as sensor_size. Can be a single value or [x, y] pair.
sensor_size	Optional sensor [width, height] with the same units/scale as focal_len. If omitted, pixels are assumed square and focal_len normalised and unitless (i.e. focal_len = focal length / max(sensor width & height)).
cx, cy	Optional principal point offsets in normalised image coordinates. Values default to zero if not supplied.
k1, k2, …	Optional distortion coefficients for the camera type. Values default to zero if not supplied.

Available frame camera types and their distortion coefficients are detailed below:

type	Coefficients	Description
pinhole		Pinhole camera model with no distortion.
brown	k1, k2, p1, p2, k3	Brown-Conrady lens distortion compatible with OpenDroneMap / OpenSfM perspective, simple_radial, radial and brown model parameters, and the 4- and 5-coefficient versions of the OpenCV general model.
fisheye	k1, k2, k3, k4	Fisheye lens distortion Compatible with OpenDroneMap / OpenSfM, and OpenCV fisheye model parameters. The OpenDroneMap / OpenSfM model is a special case of the OpenCV version with k3, k4 = 0.
opencv	k1, k2, p1, p2, k3, k4, k5, k6, s1, s2, s3, s4, tx, ty	OpenCV general camera model. Partial or special cases of the model can be specified by omitting some or all of the coefficients. E.g. if no distortion coefficients are specified, this model corresponds to pinhole, or if the first 5 distortion coefficients are specified, this model corresponds to brown.

From the API perspective, the type parameter specifies which FrameCamera subclass to use. The remaining parameters correspond to __init__() arguments for that class.

An example of a valid YAML file defining two cameras:

Pinhole camera:
    type: pinhole
    im_size: [150, 200]
    focal_len: 120.                 # focal length in mm
    sensor_size: [75., 100.]        # sensor size in mm
    cx: -0.01
    cy: 0.02
Brown camera:
    type: brown
    im_size: [400, 300]
    focal_len: 0.8333               # normalised & unitless focal length
    cx: -0.01
    cy: 0.02
    k1: -0.25
    k2: 0.2
    p1: 0.01
    p2: 0.01
    k3: -0.1