frame widening maths, cleanup
This commit is contained in:
		@ -9,7 +9,6 @@
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// #define debug_borders
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// uniforms
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uniform sampler2DRect myTextureY;
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uniform sampler2DRect myTextureU;
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uniform sampler2DRect myTextureV;
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@ -17,42 +16,41 @@ uniform vec2 myResolution;
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uniform float pts;
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// parameters
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const vec2 sensor_dimensions = vec2(5.949440, 5.205760);
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const float fisheye_focal_length = 2.92;
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const float rectilinear_focal_length = 2.102263;
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const vec2 sensor_size = vec2(5.949440, 5.205760);
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const vec2 pixel_scale = vec2(0.871558, 1.0);
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const int subsampling = 4;
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const float equidistant_focal_length = 2.920000;
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const float rectilinear_focal_length = 2.102263;
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// constants
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const float subsampling_step = 1.0 / float(subsampling);
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const float subsampling_start = subsampling_step * 0.5 - 0.5;
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const float subsampling_denominator = 1.0 / float(subsampling * subsampling);
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const int subsampling = 4;
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const vec2 subsampling_step = vec2(1.0 / float(subsampling));
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const vec2 subsampling_start = subsampling_step * 0.5 - vec2(0.5);
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const float subsampling_scale = 1.0 / float(subsampling * subsampling);
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// variables
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vec2 texture_center;
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vec2 texture_to_sensor;
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vec2 sensor_to_texture;
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void initialize() {
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    texture_center = myResolution * 0.5;
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    texture_to_sensor = (sensor_dimensions / myResolution) * pixel_scale;
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    sensor_to_texture = (myResolution / sensor_dimensions);
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    texture_to_sensor = (sensor_size / myResolution) * pixel_scale;
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    sensor_to_texture = (myResolution / sensor_size);
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}
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vec2 unfish_coord(const in vec2 coord) {
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    float rectilinear_distance = length(coord);
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    float rectilinear_angle = atan(rectilinear_distance / rectilinear_focal_length);
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    float fisheye_distance = rectilinear_angle * fisheye_focal_length;
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    return coord * (fisheye_distance / rectilinear_distance);
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    float rectilinear_radius = length(coord);
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    float rectilinear_angle = atan(rectilinear_radius / rectilinear_focal_length);
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    float equidistant_radius = rectilinear_angle * equidistant_focal_length;
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    return coord * (equidistant_radius / rectilinear_radius);
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}
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vec4 unfish_pixel(const in vec2 coord) {
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    vec2 unfished = unfish_coord((coord - texture_center) * texture_to_sensor);
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    vec2 y_coord = texture_center + unfished * sensor_to_texture;
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    // y_coord.y = coord.y;
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#ifdef debug_borders
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    if (y_coord.x < 0.0 || y_coord.y < 0.0 || y_coord.x > myResolution.x || y_coord.y > myResolution.y) {
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        return vec4(1.0, 1.0, 1.0, 1.0);
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@ -74,13 +72,12 @@ void main() {
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    vec2 coord = gl_TexCoord[0].xy;
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    vec4 pixel = vec4(0.0, 0.0, 0.0, 0.0);
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    float x, y = subsampling_start;
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    for (int column = 0; column < subsampling; column++, y += subsampling_step) {
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        x = subsampling_start;
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        for (int row = 0; row < subsampling; row++, x += subsampling_step) {
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            pixel += unfish_pixel(coord + vec2(x, y));
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    for (int y = 0; y < subsampling; y++) {
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        for (int x = 0; x < subsampling; x++) {
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            vec2 offset = subsampling_start + subsampling_step * vec2(x, y);
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            pixel += unfish_pixel(coord + offset);
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        }
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    }
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    gl_FragColor = pixel * subsampling_denominator;
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    gl_FragColor = pixel * subsampling_scale;
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}
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@ -2,85 +2,101 @@
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import math
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print("\n--- sensor size (millimeters) ---\n")
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print("\n--- physical sensor ---\n")
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# https://www.sony-semicon.com/files/62/pdf/p-13_IMX677-AAPH5-J_Flyer.pdf
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sensor_total_array_width    = 5700 # p
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sensor_total_array_height   = 5160 # p
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sensor_total_array_diagonal = math.hypot(sensor_total_array_width, sensor_total_array_height)
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sensor_array_horizontal = 5700 # p
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sensor_array_vertical   = 5160 # p
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sensor_array_diagonal   = math.hypot(sensor_array_horizontal, sensor_array_vertical)
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sensor_pixel_size = 1.12 * 0.001 # mm
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sensor_total_width    = sensor_total_array_width * sensor_pixel_size
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sensor_total_height   = sensor_total_array_height * sensor_pixel_size
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sensor_total_diagonal = math.hypot(sensor_total_width, sensor_total_height)
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sensor_size_horizontal = sensor_array_horizontal * sensor_pixel_size
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sensor_size_vertical   = sensor_array_vertical   * sensor_pixel_size
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sensor_size_diagonal   = math.hypot(sensor_size_horizontal, sensor_size_vertical)
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# sensor_total_diagonal = 8.35 # mm
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# sensor_total_width    = sensor_total_diagonal * (sensor_total_array_width  / sensor_total_array_diagonal)
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# sensor_total_height   = sensor_total_diagonal * (sensor_total_array_height / sensor_total_array_diagonal)
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print("sensor  total: width = %.6f, height = %.6f, diagonal = %.6f" % (
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    sensor_total_width,
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    sensor_total_height,
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    sensor_total_diagonal))
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sensor_active_array_width    = 5599 # p
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sensor_active_array_height   = 4927 # p
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sensor_active_array_diagonal = math.hypot(sensor_active_array_width, sensor_active_array_height)
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sensor_active_width    = (sensor_active_array_width    / sensor_total_array_width)    * sensor_total_width
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sensor_active_height   = (sensor_active_array_height   / sensor_total_array_height)   * sensor_total_height
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sensor_active_diagonal = (sensor_active_array_diagonal / sensor_total_array_diagonal) * sensor_total_diagonal
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print("sensor active: width = %.6f, height = %.6f, diagonal = %.6f" % (
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    sensor_active_width,
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    sensor_active_height,
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    sensor_active_diagonal))
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print("sensor size : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
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    sensor_size_horizontal,
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    sensor_size_vertical,
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    sensor_size_diagonal))
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# https://community.gopro.com/s/article/HERO11-Black-Video-Settings-And-Resolutions
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gopro_array_width    = 5312 # p
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gopro_array_height   = 4648 # p
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gopro_array_diagonal = math.hypot(gopro_array_width, gopro_array_height)
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gopro_array_horizontal = 5312 # p
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gopro_array_vertical   = 4648 # p
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gopro_array_diagonal   = math.hypot(gopro_array_horizontal, gopro_array_vertical)
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gopro_sensor_width    = (gopro_array_width    / sensor_total_array_width)    * sensor_total_width
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gopro_sensor_height   = (gopro_array_height   / sensor_total_array_height)   * sensor_total_height
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gopro_sensor_diagonal = (gopro_array_diagonal / sensor_total_array_diagonal) * sensor_total_diagonal
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gopro_size_horizontal = (gopro_array_horizontal / sensor_array_horizontal) * sensor_size_horizontal
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gopro_size_vertical   = (gopro_array_vertical   / sensor_array_vertical)   * sensor_size_vertical
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gopro_size_diagonal   = (gopro_array_diagonal   / sensor_array_diagonal)   * sensor_size_diagonal
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print("gopro  active: width = %.6f, height = %.6f, diagonal = %.6f" % (
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    gopro_sensor_width,
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    gopro_sensor_height,
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    gopro_sensor_diagonal))
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print("gopro  size : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
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    gopro_size_horizontal,
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    gopro_size_vertical,
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    gopro_size_diagonal))
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# https://thinglabs.io/gopro-focal-length-guide
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# https://thinglabs.io/gopro-focal-radius-guide
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gopro_focal_length = 2.92 # mm
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print("\n--- fisheye field of view (degrees) ---\n")
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gopro_radius_horizontal = gopro_size_horizontal * 0.5
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gopro_radius_vertical   = gopro_size_vertical   * 0.5
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gopro_radius_diagonal   = gopro_size_diagonal   * 0.5
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# https://en.wikipedia.org/wiki/Fisheye_lens
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equidistant_angle  = lambda length: math.degrees(length / gopro_focal_length)
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equidistant_angle  = lambda radius: math.degrees(radius / gopro_focal_length)
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gopro_fov_width    = 2.0 * equidistant_angle(gopro_sensor_width    * 0.5)
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gopro_fov_height   = 2.0 * equidistant_angle(gopro_sensor_height   * 0.5)
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gopro_fov_diagonal = 2.0 * equidistant_angle(gopro_sensor_diagonal * 0.5)
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gopro_fov_horizontal = 2.0 * equidistant_angle(gopro_radius_horizontal)
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gopro_fov_vertical   = 2.0 * equidistant_angle(gopro_radius_vertical)
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gopro_fov_diagonal   = 2.0 * equidistant_angle(gopro_radius_diagonal)
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print("gopro fov: width = %.6f, height = %.6f, diagonal = %.6f" % (
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    gopro_fov_width,
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    gopro_fov_height,
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print("gopro  fov  : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (deg)" % (
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    gopro_fov_horizontal,
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    gopro_fov_vertical,
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    gopro_fov_diagonal))
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print("\n--- rectilinear focal length (mm) ---\n")
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print("\n--- rectilinear re-projection, preserving vertical fov ---\n")
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rectilinear_focal_length = lambda length: length * math.tan(math.radians(90.0 - equidistant_angle(length)))
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rectilinear_focal_length = lambda radius: radius * math.tan(math.radians(90.0 - equidistant_angle(radius)))
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rectilinear_focal_length_width    = rectilinear_focal_length(gopro_sensor_width    * 0.5)
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rectilinear_focal_length_height   = rectilinear_focal_length(gopro_sensor_height   * 0.5)
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rectilinear_focal_length_diagonal = rectilinear_focal_length(gopro_sensor_diagonal * 0.5)
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rectilinear_focal_length_horizontal = rectilinear_focal_length(gopro_radius_horizontal)
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rectilinear_focal_length_vertical   = rectilinear_focal_length(gopro_radius_vertical)
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rectilinear_focal_length_diagonal   = rectilinear_focal_length(gopro_radius_diagonal)
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print("rectilinear focal length: width = %.6f, height = %.6f, diagonal = %.6f" % (
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    rectilinear_focal_length_width,
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    rectilinear_focal_length_height,
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print("linear focal: horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
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    rectilinear_focal_length_horizontal,
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    rectilinear_focal_length_vertical,
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    rectilinear_focal_length_diagonal))
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rectilinear_radius = lambda angle,  focal_length: focal_length * math.tan(math.radians(angle))
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rectilinear_angle  = lambda radius, focal_length: math.degrees(math.atan(radius / focal_length))
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preserved_fov_horizontal = 2.0 * rectilinear_angle(gopro_radius_horizontal, rectilinear_focal_length_vertical)
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preserved_fov_vertical   = 2.0 * rectilinear_angle(gopro_radius_vertical,   rectilinear_focal_length_vertical)
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preserved_fov_diagonal   = 2.0 * rectilinear_angle(gopro_radius_diagonal,   rectilinear_focal_length_vertical)
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print("linear fov  : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (deg)" % (
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    preserved_fov_horizontal,
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    preserved_fov_vertical,
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    preserved_fov_diagonal))
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print("\n--- shader parameters ---\n")
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rectilinear_angle_horizontal = rectilinear_angle(gopro_radius_horizontal,       rectilinear_focal_length_horizontal)
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preserved_radius_horizontal  = rectilinear_radius(rectilinear_angle_horizontal, rectilinear_focal_length_vertical)
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pixel_scale = gopro_radius_horizontal / preserved_radius_horizontal
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print("""// parameters
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const vec2 sensor_size = vec2(%.6f, %.6f);
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const vec2 pixel_scale = vec2(%.6f, 1.0);
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const float equidistant_focal_length = %.6f;
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const float rectilinear_focal_length = %.6f;
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""" % (
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    gopro_size_horizontal, gopro_size_vertical,
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    pixel_scale,
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    gopro_focal_length,
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    rectilinear_focal_length_vertical)
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)
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