in vec2 flow_tc;
in vec2 patch_bottom_left_texel; // Center of bottom-left texel of patch.
-out vec2 out_flow;
+out vec3 out_flow;
uniform sampler2D flow_tex, grad0_tex, image0_tex, image1_tex;
uniform vec2 image_size, inv_image_size;
mat2 H_inv = inverse(H);
- // Fetch the initial guess for the flow. (We need the normalization step
- // because densification works by accumulating; see the comments on the
- // Densify class.)
- vec3 prev_flow = texture(flow_tex, flow_tc).xyz;
- vec2 initial_u;
- if (prev_flow.z < 1e-3) {
- initial_u = vec2(0.0, 0.0);
- } else {
- initial_u = prev_flow.xy / prev_flow.z;
- }
+ // Fetch the initial guess for the flow.
+ vec2 initial_u = texture(flow_tex, flow_tc).xy;
// Note: The flow is in OpenGL coordinates [0..1], but the calculations
// generally come out in pixels since the gradient is in pixels,
// so we need to convert at the end.
vec2 u = initial_u;
+ float mean_diff, first_mean_diff;
for (uint i = 0; i < num_iterations; ++i) {
vec2 du = vec2(0.0, 0.0);
// sum(S^T * (x - y)) = [what we calculated] - (µ1 - µ2) sum(S^T)
//
// so we can just subtract away the mean difference here.
- du -= grad_sum * (warped_sum - template_sum) * (1.0 / (patch_size * patch_size));
+ mean_diff = (warped_sum - template_sum) * (1.0 / (patch_size * patch_size));
+ du -= grad_sum * mean_diff;
+
+ if (i == 0) {
+ first_mean_diff = mean_diff;
+ }
// Do the actual update.
u -= (H_inv * du) * inv_image_size;
u.y * image_size.y < -(patch_size * 0.5f) ||
(1.0 - u.y) * image_size.y < -(patch_size * 0.5f)) {
u = initial_u;
+ mean_diff = first_mean_diff;
}
- out_flow = u;
+ // NOTE: The mean patch diff will be for the second-to-last patch,
+ // not the true position of du. But hopefully, it will be very close.
+ out_flow = vec3(u.x, u.y, mean_diff);
}