version, precison and rotate

gopro_8:7/compute_gopro_8:7.py

@@ -1,36 +0,0 @@
-# RozK
-# Computes fisheye removal parameters for GoPro 11+, 8:7 ratio, without hypersmooth,
-# keeping the vertical FOV and widening the frame to preserve the diagonal FOV
-
-# https://www.bobatkins.com/photography/technical/field_of_view.html
-# https://community.gopro.com/s/article/HERO11-Black-Mini-Digital-Lenses-FOV-Information?language=fr
-
-import math
-
-frame_width = 8
-frame_height = 7
-input_ratio = frame_width / frame_height
-
-input_vertical_fov = 108.0
-input_diagonal_fov = 156.0
-
-input_vertical_length = math.radians(input_vertical_fov * 0.5)
-input_diagonal_length = math.radians(input_diagonal_fov * 0.5)
-
-output_horizontal_length = math.sqrt((input_diagonal_length ** 2) / (input_vertical_length ** 2))
-output_diagonal_length = math.hypot(output_horizontal_length, input_vertical_length)
-output_diagonal_fov = math.degrees(math.atan(output_diagonal_length)) * 2.0
-
-output_ratio = 1.0 / (output_horizontal_length / input_vertical_length)
-
-print("Output FOV   = %f" % output_diagonal_fov)
-print("Output Ratio = %f" % output_ratio)
-print("= Resolutions =====================")
-
-def width_rounded_8(height):
-    width = int(round(height * input_ratio))
-    return ((width + 4) // 8) * 8
-
-print("HD             = %i x 720" % width_rounded_8(720))
-print("Full HD        = %i x 1080" % width_rounded_8(1080))
-print("4K             = %i x 2160" % width_rounded_8(2160))

gopro_8:7/unfish_gopro_8:7.glsl

@@ -1,12 +1,14 @@
+#version 130
 // RozK
 // Fisheye removal for GoPro 11+, 8:7 ratio, without hypersmooth
-// Adapted from https://github.com/duducosmos/defisheye
-// itself based on http://www.fmwconcepts.com/imagemagick/defisheye/index.php
 
 #extension GL_ARB_texture_rectangle: enable
 
-// TODO: investigate
-// precision highp float;
+#undef highp // defined by Qt-OpenGl
+#define rotate_180
+//#define debug_borders
+
+precision highp float;
 
 // uniforms
 uniform sampler2DRect myTextureY;
@@ -16,25 +18,50 @@ uniform vec2 myResolution;
 uniform float pts;
 
 // parameters
-const float input_fov = 156.0;
-const float output_fov = 124.45;
-const vec2 pixel_scale = vec2(0.652485, 1.0);
-const int subsampling = 4;
+const vec2 sensor_size = vec2(5.949440, 5.205760);
+const vec2 pixel_scale = vec2(0.871558, 1.0);
+const float equidistant_focal_length = 2.920000;
+const float rectilinear_focal_length = 2.102263;
 
-// subsampling constants
-const float substep = 1.0 / float(subsampling);
-const float substart = substep * 0.5 - 0.5;
-const float subscale = 1.0 / float(subsampling * subsampling);
+// constants
+const int subsampling = 4;
+const vec2 subsampling_step = vec2(1.0 / float(subsampling));
+const vec2 subsampling_start = subsampling_step * 0.5 - vec2(0.5);
+const float subsampling_scale = 1.0 / float(subsampling * subsampling);
 
 // variables
-vec2 center;
-float diameter;
-float input_len;
-float inv_output_len;
+vec2 texture_center;
+vec2 texture_to_sensor;
+vec2 sensor_to_texture;
+
+void initialize() {
+    texture_center = myResolution * 0.5;
+    texture_to_sensor = (sensor_size / myResolution) * pixel_scale;
+#ifdef rotate_180
+    texture_to_sensor *= -1.0;
+#endif
+    sensor_to_texture = (myResolution / sensor_size);
+}
+
+vec2 unfish_coord(const in vec2 coord) {
+    float rectilinear_radius = length(coord);
+    float rectilinear_angle = atan(rectilinear_radius / rectilinear_focal_length);
+    float equidistant_radius = rectilinear_angle * equidistant_focal_length;
+    return coord * (equidistant_radius / rectilinear_radius);
+}
+
+vec4 unfish_pixel(const in vec2 coord) {
+    vec2 unfished = unfish_coord((coord - texture_center) * texture_to_sensor);
+    vec2 y_coord = texture_center + unfished * sensor_to_texture;
+
+    // y_coord.y = coord.y;
+
+#ifdef debug_borders
+    if (y_coord.x < 0.0 || y_coord.y < 0.0 || y_coord.x > myResolution.x || y_coord.y > myResolution.y) {
+        return vec4(1.0);
+    }
+#endif
 
-vec4 unfish(const in vec2 coord) {
-    float len = max(0.001, length(coord));
-    vec2 y_coord = center + coord * ((input_len / len) * atan(len * inv_output_len));
     vec2 uv_coord = y_coord * 0.5;
     return vec4(
         texture2DRect(myTextureY, y_coord).r,
@@ -45,21 +72,17 @@ vec4 unfish(const in vec2 coord) {
 }
 
 void main() {
-    center = myResolution * 0.5;
-    diameter = length(myResolution);
-    input_len = diameter / radians(input_fov);
-    inv_output_len = (2.0 * tan(radians(output_fov * 0.5))) / diameter;
+    initialize();
 
-    vec2 coord = gl_TexCoord[0].xy - center;
-    vec4 pixel = vec4(0.0, 0.0, 0.0, 0.0);
+    vec2 coord = gl_TexCoord[0].xy;
+    vec4 pixel = vec4(0.0);
 
-    float x, y = substart;
-    for (int column = 0; column < subsampling; column++, y += substep) {
-        x = substart;
-        for (int row = 0; row < subsampling; row++, x += substep) {
-            pixel += unfish((coord + vec2(x, y)) * pixel_scale);
+    for (int y = 0; y < subsampling; y++) {
+        for (int x = 0; x < subsampling; x++) {
+            vec2 offset = subsampling_start + subsampling_step * vec2(x, y);
+            pixel += unfish_pixel(coord + offset);
         }
     }
 
-    gl_FragColor = pixel * subscale;
+    gl_FragColor = pixel * subsampling_scale;
 }

gopro_8:7/unfish_gopro_8:7.py

@@ -0,0 +1,102 @@
+# RozK
+
+import math
+
+print("\n--- physical sensor ---\n")
+
+# https://www.sony-semicon.com/files/62/pdf/p-13_IMX677-AAPH5-J_Flyer.pdf
+
+sensor_array_horizontal = 5700 # p
+sensor_array_vertical   = 5160 # p
+sensor_array_diagonal   = math.hypot(sensor_array_horizontal, sensor_array_vertical)
+
+sensor_pixel_size = 1.12 * 0.001 # mm
+
+sensor_size_horizontal = sensor_array_horizontal * sensor_pixel_size
+sensor_size_vertical   = sensor_array_vertical   * sensor_pixel_size
+sensor_size_diagonal   = math.hypot(sensor_size_horizontal, sensor_size_vertical)
+
+print("sensor size : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
+    sensor_size_horizontal,
+    sensor_size_vertical,
+    sensor_size_diagonal))
+
+# https://community.gopro.com/s/article/HERO11-Black-Video-Settings-And-Resolutions
+
+gopro_array_horizontal = 5312 # p
+gopro_array_vertical   = 4648 # p
+gopro_array_diagonal   = math.hypot(gopro_array_horizontal, gopro_array_vertical)
+
+gopro_size_horizontal = (gopro_array_horizontal / sensor_array_horizontal) * sensor_size_horizontal
+gopro_size_vertical   = (gopro_array_vertical   / sensor_array_vertical)   * sensor_size_vertical
+gopro_size_diagonal   = (gopro_array_diagonal   / sensor_array_diagonal)   * sensor_size_diagonal
+
+print("gopro  size : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
+    gopro_size_horizontal,
+    gopro_size_vertical,
+    gopro_size_diagonal))
+
+# https://thinglabs.io/gopro-focal-radius-guide
+
+gopro_focal_length = 2.92 # mm
+
+gopro_radius_horizontal = gopro_size_horizontal * 0.5
+gopro_radius_vertical   = gopro_size_vertical   * 0.5
+gopro_radius_diagonal   = gopro_size_diagonal   * 0.5
+
+# https://en.wikipedia.org/wiki/Fisheye_lens
+
+equidistant_angle  = lambda radius: math.degrees(radius / gopro_focal_length)
+
+gopro_fov_horizontal = 2.0 * equidistant_angle(gopro_radius_horizontal)
+gopro_fov_vertical   = 2.0 * equidistant_angle(gopro_radius_vertical)
+gopro_fov_diagonal   = 2.0 * equidistant_angle(gopro_radius_diagonal)
+
+print("gopro  fov  : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (deg)" % (
+    gopro_fov_horizontal,
+    gopro_fov_vertical,
+    gopro_fov_diagonal))
+
+print("\n--- rectilinear re-projection, preserving vertical fov ---\n")
+
+rectilinear_focal_length = lambda radius: radius * math.tan(math.radians(90.0 - equidistant_angle(radius)))
+
+rectilinear_focal_length_horizontal = rectilinear_focal_length(gopro_radius_horizontal)
+rectilinear_focal_length_vertical   = rectilinear_focal_length(gopro_radius_vertical)
+rectilinear_focal_length_diagonal   = rectilinear_focal_length(gopro_radius_diagonal)
+
+print("linear focal: horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
+    rectilinear_focal_length_horizontal,
+    rectilinear_focal_length_vertical,
+    rectilinear_focal_length_diagonal))
+
+rectilinear_radius = lambda angle,  focal_length: focal_length * math.tan(math.radians(angle))
+rectilinear_angle  = lambda radius, focal_length: math.degrees(math.atan(radius / focal_length))
+
+preserved_fov_horizontal = 2.0 * rectilinear_angle(gopro_radius_horizontal, rectilinear_focal_length_vertical)
+preserved_fov_vertical   = 2.0 * rectilinear_angle(gopro_radius_vertical,   rectilinear_focal_length_vertical)
+preserved_fov_diagonal   = 2.0 * rectilinear_angle(gopro_radius_diagonal,   rectilinear_focal_length_vertical)
+
+print("linear fov  : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (deg)" % (
+    preserved_fov_horizontal,
+    preserved_fov_vertical,
+    preserved_fov_diagonal))
+
+print("\n--- shader parameters ---\n")
+
+rectilinear_angle_horizontal = rectilinear_angle(gopro_radius_horizontal,       rectilinear_focal_length_horizontal)
+preserved_radius_horizontal  = rectilinear_radius(rectilinear_angle_horizontal, rectilinear_focal_length_vertical)
+
+pixel_scale = gopro_radius_horizontal / preserved_radius_horizontal
+
+print("""// parameters
+const vec2 sensor_size = vec2(%.6f, %.6f);
+const vec2 pixel_scale = vec2(%.6f, 1.0);
+const float equidistant_focal_length = %.6f;
+const float rectilinear_focal_length = %.6f;
+""" % (
+    gopro_size_horizontal, gopro_size_vertical,
+    pixel_scale,
+    gopro_focal_length,
+    rectilinear_focal_length_vertical)
+)