/**
* Run the optical flow with EDGEFLOW on a new image frame
* @param[in] *opticflow The opticalflow structure that keeps track of previous images
* @param[in] *state The state of the drone
* @param[in] *img The image frame to calculate the optical flow from
* @param[out] *result The optical flow result
*/
void calc_edgeflow_tot(struct opticflow_t *opticflow, struct opticflow_state_t *state, struct image_t *img,
struct opticflow_result_t *result)
{
// Define Static Variables
static struct edge_hist_t edge_hist[MAX_HORIZON];
static uint8_t current_frame_nr = 0;
struct edge_flow_t edgeflow;
static uint8_t previous_frame_offset[2] = {1, 1};
// Define Normal variables
struct edgeflow_displacement_t displacement;
displacement.x = malloc(sizeof(int32_t) * img->w);
displacement.y = malloc(sizeof(int32_t) * img->h);
// If the methods just switched to this one, reintialize the
// array of edge_hist structure.
if (opticflow->just_switched_method == 1) {
int i;
for (i = 0; i < MAX_HORIZON; i++) {
edge_hist[i].x = malloc(sizeof(int32_t) * img->w);
edge_hist[i].y = malloc(sizeof(int32_t) * img->h);
FLOAT_RATES_ZERO(edge_hist[i].rates);
}
}
uint16_t disp_range;
if (opticflow->search_distance < DISP_RANGE_MAX) {
disp_range = opticflow->search_distance;
} else {
disp_range = DISP_RANGE_MAX;
}
uint16_t window_size;
if (opticflow->window_size < MAX_WINDOW_SIZE) {
window_size = opticflow->window_size;
} else {
window_size = MAX_WINDOW_SIZE;
}
uint16_t RES = opticflow->subpixel_factor;
//......................Calculating EdgeFlow..................... //
// Calculate current frame's edge histogram
int32_t *edge_hist_x = edge_hist[current_frame_nr].x;
int32_t *edge_hist_y = edge_hist[current_frame_nr].y;
calculate_edge_histogram(img, edge_hist_x, 'x', 0);
calculate_edge_histogram(img, edge_hist_y, 'y', 0);
// Copy frame time and angles of image to calculated edge histogram
edge_hist[current_frame_nr].frame_time = img->ts;
edge_hist[current_frame_nr].rates = state->rates;
// Calculate which previous edge_hist to compare with the current
uint8_t previous_frame_nr[2];
calc_previous_frame_nr(result, opticflow, current_frame_nr, previous_frame_offset, previous_frame_nr);
//Select edge histogram from the previous frame nr
int32_t *prev_edge_histogram_x = edge_hist[previous_frame_nr[0]].x;
int32_t *prev_edge_histogram_y = edge_hist[previous_frame_nr[1]].y;
//Calculate the corresponding derotation of the two frames
int16_t der_shift_x = 0;
int16_t der_shift_y = 0;
if (opticflow->derotation) {
der_shift_x = (int16_t)(edge_hist[current_frame_nr].rates.p /
result->fps *
(float)img->w / (OPTICFLOW_FOV_W) * opticflow->derotation_correction_factor_x);
der_shift_y = (int16_t)(edge_hist[current_frame_nr].rates.q /
result->fps *
(float)img->h / (OPTICFLOW_FOV_H) * opticflow->derotation_correction_factor_y);
}
// Estimate pixel wise displacement of the edge histograms for x and y direction
calculate_edge_displacement(edge_hist_x, prev_edge_histogram_x,
displacement.x, img->w,
window_size, disp_range, der_shift_x);
calculate_edge_displacement(edge_hist_y, prev_edge_histogram_y,
displacement.y, img->h,
window_size, disp_range, der_shift_y);
// Fit a line on the pixel displacement to estimate
// the global pixel flow and divergence (RES is resolution)
line_fit(displacement.x, &edgeflow.div_x,
&edgeflow.flow_x, img->w,
window_size + disp_range, RES);
line_fit(displacement.y, &edgeflow.div_y,
&edgeflow.flow_y, img->h,
window_size + disp_range, RES);
/* Save Resulting flow in results
* Warning: The flow detected here is different in sign
* and size, therefore this will be multiplied with
* the same subpixel factor and -1 to make it on par with
* the LK algorithm of t opticalflow_calculator.c
* */
edgeflow.flow_x = -1 * edgeflow.flow_x;
edgeflow.flow_y = -1 * edgeflow.flow_y;
result->flow_x = (int16_t)edgeflow.flow_x / previous_frame_offset[0];
result->flow_y = (int16_t)edgeflow.flow_y / previous_frame_offset[1];
//Fill up the results optic flow to be on par with LK_fast9
result->flow_der_x = result->flow_x;
result->flow_der_y = result->flow_y;
result->corner_cnt = getAmountPeaks(edge_hist_x, 500 , img->w);
result->tracked_cnt = getAmountPeaks(edge_hist_x, 500 , img->w);
result->divergence = (float)edgeflow.flow_x / RES;
result->div_size = 0.0f;
result->noise_measurement = 0.0f;
result->surface_roughness = 0.0f;
//......................Calculating VELOCITY ..................... //
/*Estimate fps per direction
* This is the fps with adaptive horizon for subpixel flow, which is not similar
* to the loop speed of the algorithm. The faster the quadcopter flies
* the higher it becomes
*/
float fps_x = 0;
float fps_y = 0;
float time_diff_x = (float)(timeval_diff(&edge_hist[previous_frame_nr[0]].frame_time, &img->ts)) / 1000.;
float time_diff_y = (float)(timeval_diff(&edge_hist[previous_frame_nr[1]].frame_time, &img->ts)) / 1000.;
fps_x = 1 / (time_diff_x);
fps_y = 1 / (time_diff_y);
result->fps = fps_x;
// Calculate velocity
float vel_x = edgeflow.flow_x * fps_x * state->agl * OPTICFLOW_FOV_W / (img->w * RES);
float vel_y = edgeflow.flow_y * fps_y * state->agl * OPTICFLOW_FOV_H / (img->h * RES);
//Apply a median filter to the velocity if wanted
if (opticflow->median_filter == true) {
result->vel_x = (float)update_median_filter(&vel_x_filt, (int32_t)(vel_x * 1000)) / 1000;
result->vel_y = (float)update_median_filter(&vel_y_filt, (int32_t)(vel_y * 1000)) / 1000;
} else {
result->vel_x = vel_x;
result->vel_y = vel_y;
}
result->noise_measurement = 0.2;
#if OPTICFLOW_SHOW_FLOW
draw_edgeflow_img(img, edgeflow, prev_edge_histogram_x, edge_hist_x);
#endif
// Increment and wrap current time frame
current_frame_nr = (current_frame_nr + 1) % MAX_HORIZON;
}
/**
* Run the optical flow with EDGEFLOW on a new image frame
* @param[in] *opticflow The opticalflow structure that keeps track of previous images
* @param[in] *state The state of the drone
* @param[in] *img The image frame to calculate the optical flow from
* @param[out] *result The optical flow result
*/
void calc_edgeflow_tot(struct opticflow_t *opticflow, struct opticflow_state_t *state, struct image_t *img,
struct opticflow_result_t *result)
{
// Define Static Variables
static struct edge_hist_t edge_hist[MAX_HORIZON];
static uint8_t current_frame_nr = 0;
static struct edge_flow_t edgeflow;
static uint8_t previous_frame_offset[2] = {1, 1};
// Define Normal variables
struct edgeflow_displacement_t displacement;
uint16_t disp_range;
if (opticflow->search_distance < DISP_RANGE_MAX) {
disp_range = opticflow->search_distance;
} else {
disp_range = DISP_RANGE_MAX;
}
uint16_t window_size;
if (opticflow->window_size < MAX_WINDOW_SIZE) {
window_size = opticflow->window_size;
} else {
window_size = MAX_WINDOW_SIZE;
}
uint16_t RES = opticflow->subpixel_factor;
//......................Calculating EdgeFlow..................... //
// Calculate current frame's edge histogram
int32_t *edge_hist_x = edge_hist[current_frame_nr].x;
int32_t *edge_hist_y = edge_hist[current_frame_nr].y;
calculate_edge_histogram(img, edge_hist_x, 'x', 0);
calculate_edge_histogram(img, edge_hist_y, 'y', 0);
// Copy frame time and angles of image to calculated edge histogram
memcpy(&edge_hist[current_frame_nr].frame_time, &img->ts, sizeof(struct timeval));
edge_hist[current_frame_nr].pitch = state->theta;
edge_hist[current_frame_nr].roll = state->phi;
// Calculate which previous edge_hist to compare with the current
uint8_t previous_frame_nr[2];
calc_previous_frame_nr(result, opticflow, current_frame_nr, previous_frame_offset, previous_frame_nr);
//Select edge histogram from the previous frame nr
int32_t *prev_edge_histogram_x = edge_hist[previous_frame_nr[0]].x;
int32_t *prev_edge_histogram_y = edge_hist[previous_frame_nr[1]].y;
//Calculate the corresponding derotation of the two frames
int16_t der_shift_x = 0;
int16_t der_shift_y = 0;
if (opticflow->derotation) {
der_shift_x = -(int16_t)((edge_hist[previous_frame_nr[0]].roll - edge_hist[current_frame_nr].roll) *
(float)img->w / (OPTICFLOW_FOV_W));
der_shift_y = -(int16_t)((edge_hist[previous_frame_nr[1]].pitch - edge_hist[current_frame_nr].pitch) *
(float)img->h / (OPTICFLOW_FOV_H));
}
// Estimate pixel wise displacement of the edge histograms for x and y direction
calculate_edge_displacement(edge_hist_x, prev_edge_histogram_x,
displacement.x, img->w,
window_size, disp_range, der_shift_x);
calculate_edge_displacement(edge_hist_y, prev_edge_histogram_y,
displacement.y, img->h,
window_size, disp_range, der_shift_y);
// Fit a line on the pixel displacement to estimate
// the global pixel flow and divergence (RES is resolution)
line_fit(displacement.x, &edgeflow.div_x,
&edgeflow.flow_x, img->w,
window_size + disp_range, RES);
line_fit(displacement.y, &edgeflow.div_y,
&edgeflow.flow_y, img->h,
window_size + disp_range, RES);
/* Save Resulting flow in results
* Warning: The flow detected here is different in sign
* and size, therefore this will be multiplied with
* the same subpixel factor and -1 to make it on par with
* the LK algorithm of t opticalflow_calculator.c
* */
edgeflow.flow_x = -1 * edgeflow.flow_x;
edgeflow.flow_y = -1 * edgeflow.flow_y;
result->flow_x = (int16_t)edgeflow.flow_x / previous_frame_offset[0];
result->flow_y = (int16_t)edgeflow.flow_y / previous_frame_offset[1];
//Fill up the results optic flow to be on par with LK_fast9
result->flow_der_x = result->flow_x;
result->flow_der_y = result->flow_y;
result->corner_cnt = getAmountPeaks(edge_hist_x, 500 , img->w);
result->tracked_cnt = getAmountPeaks(edge_hist_x, 500 , img->w);
result->divergence = (float)edgeflow.flow_x / RES;
result->div_size = 0.0f;
result->noise_measurement = 0.0f;
result->surface_roughness = 0.0f;
//......................Calculating VELOCITY ..................... //
/*Estimate fps per direction
* This is the fps with adaptive horizon for subpixel flow, which is not similar
* to the loop speed of the algorithm. The faster the quadcopter flies
* the higher it becomes
*/
float fps_x = 0;
float fps_y = 0;
float time_diff_x = (float)(timeval_diff(&edge_hist[previous_frame_nr[0]].frame_time, &img->ts)) / 1000.;
float time_diff_y = (float)(timeval_diff(&edge_hist[previous_frame_nr[1]].frame_time, &img->ts)) / 1000.;
fps_x = 1 / (time_diff_x);
fps_y = 1 / (time_diff_y);
result->fps = fps_x;
// Calculate velocity
float vel_x = edgeflow.flow_x * fps_x * state->agl * OPTICFLOW_FOV_W / (img->w * RES);
float vel_y = edgeflow.flow_y * fps_y * state->agl * OPTICFLOW_FOV_H / (img->h * RES);
result->vel_x = vel_x;
result->vel_y = vel_y;
/* Rotate velocities from camera frame coordinates to body coordinates.
* IMPORTANT This frame to body orientation should be the case for the Parrot
* ARdrone and Bebop, however this can be different for other quadcopters
* ALWAYS double check!
*/
result->vel_body_x = - vel_y;
result->vel_body_y = vel_x;
#if OPTICFLOW_DEBUG && OPTICFLOW_SHOW_FLOW
draw_edgeflow_img(img, edgeflow, displacement, *edge_hist_x)
#endif
// Increment and wrap current time frame
current_frame_nr = (current_frame_nr + 1) % MAX_HORIZON;
}