6 uniform sampler2D I_x_y_tex, I_t_tex;
7 uniform sampler2D diff_flow_tex, base_flow_tex;
8 uniform sampler2D beta_0_tex;
9 uniform sampler2D smoothness_x_tex, smoothness_y_tex;
11 // TODO: Consider a specialized version for the case where we know that du = dv = 0,
12 // since we run so few iterations.
17 // Read the flow (on top of the u0/v0 flow).
18 vec2 diff_flow = texture(diff_flow_tex, tc).xy;
19 float du = diff_flow.x;
20 float dv = diff_flow.y;
22 // Read the first derivatives.
23 vec2 I_x_y = texture(I_x_y_tex, tc).xy;
26 float I_t = texture(I_t_tex, tc).x;
28 // E_I term. Note that we don't square β_0, in line with DeepFlow,
29 // even though it's probably an error.
31 // TODO: Evaluate squaring β_0.
32 // FIXME: Should the penalizer be adjusted for 0..1 intensity range instead of 0..255?
33 // TODO: Multiply by some alpha.
34 float beta_0 = texture(beta_0_tex, tc).x;
35 float k1 = beta_0 * inversesqrt(beta_0 * (I_x * du + I_y * dv + I_t) * (I_x * du + I_y * dv + I_t) + 1e-6);
36 float A11 = k1 * I_x * I_x;
37 float A12 = k1 * I_x * I_y;
38 float A22 = k1 * I_y * I_y;
39 float b1 = -k1 * I_t * I_x;
40 float b2 = -k1 * I_t * I_y;
42 // Compute the second derivatives. First I_xx and I_xy.
43 vec2 I_x_y_m2 = textureOffset(I_x_y_tex, tc, ivec2(-2, 0)).xy;
44 vec2 I_x_y_m1 = textureOffset(I_x_y_tex, tc, ivec2(-1, 0)).xy;
45 vec2 I_x_y_p1 = textureOffset(I_x_y_tex, tc, ivec2( 1, 0)).xy;
46 vec2 I_x_y_p2 = textureOffset(I_x_y_tex, tc, ivec2( 2, 0)).xy;
47 vec2 I_xx_yx = (I_x_y_p1 - I_x_y_m1) * (2.0/3.0) + (I_x_y_m2 - I_x_y_p2) * (1.0/12.0);
48 float I_xx = I_xx_yx.x;
49 float I_xy = I_xx_yx.y;
51 // And now I_yy; I_yx = I_xy, bar rounding differences, so we don't
52 // bother computing it. We still have to sample the x component,
53 // though, but we can throw it away immediately.
54 float I_y_m2 = textureOffset(I_x_y_tex, tc, ivec2(0, -2)).y;
55 float I_y_m1 = textureOffset(I_x_y_tex, tc, ivec2(0, -1)).y;
56 float I_y_p1 = textureOffset(I_x_y_tex, tc, ivec2(0, 1)).y;
57 float I_y_p2 = textureOffset(I_x_y_tex, tc, ivec2(0, 2)).y;
58 float I_yy = (I_y_p1 - I_y_m1) * (2.0/3.0) + (I_y_m2 - I_y_p2) * (1.0/12.0);
60 // Finally I_xt and I_yt. (We compute these as I_tx and I_yt.)
61 vec2 I_t_m2 = textureOffset(I_t_tex, tc, ivec2(-2, 0)).xy;
62 vec2 I_t_m1 = textureOffset(I_t_tex, tc, ivec2(-1, 0)).xy;
63 vec2 I_t_p1 = textureOffset(I_t_tex, tc, ivec2( 1, 0)).xy;
64 vec2 I_t_p2 = textureOffset(I_t_tex, tc, ivec2( 2, 0)).xy;
65 vec2 I_tx_ty = (I_t_p1 - I_t_m1) * (2.0/3.0) + (I_t_m2 - I_t_p2) * (1.0/12.0);
66 float I_xt = I_tx_ty.x;
67 float I_yt = I_tx_ty.y;
69 // E_G term. Same TODOs as E_I. Same normalization as beta_0
70 // (see derivatives.frag).
71 float beta_x = 1.0 / (I_xx * I_xx + I_xy * I_xy + 1e-7);
72 float beta_y = 1.0 / (I_xy * I_xy + I_yy * I_yy + 1e-7);
73 float k2 = inversesqrt(
74 beta_x * (I_xx * du + I_xy * dv + I_xt) * (I_xx * du + I_xy * dv + I_xt) +
75 beta_y * (I_xy * du + I_yy * dv + I_yt) * (I_xy * du + I_yy * dv + I_yt) +
77 float k_x = k2 * beta_x;
78 float k_y = k2 * beta_y;
79 A11 += k_x * I_xx * I_xx + k_y * I_xy * I_xy;
80 A12 += k_x * I_xx * I_xy + k_y * I_xy * I_yy;
81 A22 += k_x * I_xy * I_xy + k_y * I_yy * I_yy;
82 b1 -= k_x * I_xx * I_xt + k_y * I_xy * I_yt;
83 b2 -= k_x * I_xy * I_xt + k_y * I_yy * I_yt;
85 // E_S term, sans the part on the right-hand side that deals with
86 // the neighboring pixels.
87 // TODO: Multiply by some gamma.
88 float smooth_l = textureOffset(smoothness_x_tex, tc, ivec2(-1, 0)).x;
89 float smooth_r = texture(smoothness_x_tex, tc).x;
90 float smooth_d = textureOffset(smoothness_y_tex, tc, ivec2( 0, -1)).x;
91 float smooth_u = texture(smoothness_y_tex, tc).x;
92 A11 += smooth_l + smooth_r + smooth_d + smooth_u;
93 A22 += smooth_l + smooth_r + smooth_d + smooth_u;
95 // Laplacian of (u0, v0).
97 smooth_l * textureOffset(base_flow_tex, tc, ivec2(-1, 0)).xy +
98 smooth_r * textureOffset(base_flow_tex, tc, ivec2( 1, 0)).xy +
99 smooth_d * textureOffset(base_flow_tex, tc, ivec2( 0, -1)).xy +
100 smooth_u * textureOffset(base_flow_tex, tc, ivec2( 0, 1)).xy -
101 (smooth_l + smooth_r + smooth_d + smooth_u) * texture(base_flow_tex, tc).xy;
105 // Encode the equation down into four uint32s.
106 equation.x = floatBitsToUint(1.0 / A11);
107 equation.y = floatBitsToUint(A12);
108 equation.z = floatBitsToUint(1.0 / A22);
109 equation.w = packHalf2x16(vec2(b1, b2));