Calculate velocity from optic flow. More...

#include "std.h"
#include "inter_thread_data.h"
#include "lib/vision/image.h"
#include "lib/v4l/v4l2.h"

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Data Structures
struct	opticflow_t

Macros
#define	FAST9_MAX_CORNERS 512

Functions
void	opticflow_calc_init (struct opticflow_t *opticflow)
	Initialize the opticflow calculator. More...

bool	opticflow_calc_frame (struct opticflow_t opticflow, struct image_t img, struct opticflow_result_t *result)
	Run the optical flow on a new image frame. More...

bool	calc_fast9_lukas_kanade (struct opticflow_t opticflow, struct image_t img, struct opticflow_result_t *result)
	Run the optical flow with fast9 and lukaskanade on a new image frame. More...

bool	calc_edgeflow_tot (struct opticflow_t opticflow, struct image_t img, struct opticflow_result_t *result)
	Run the optical flow with EDGEFLOW on a new image frame. More...

void	kalman_filter_opticflow_velocity (float velocity_x, float velocity_y, float acceleration_measurement, float fps, float measurement_noise, float process_noise, bool reinitialize_kalman)

Detailed Description

Calculate velocity from optic flow.

Using images from a vertical camera and IMU sensor data.

Definition in file opticflow_calculator.h.

Data Structure Documentation

struct opticflow_t

Definition at line 40 of file opticflow_calculator.h.

Collaboration diagram for opticflow_t:

Data Fields
int	actfast_gradient_method	Whether to use a simple or Sobel filter.
float	actfast_long_step	Step size to take when there is no texture.
int	actfast_min_gradient	Threshold that decides when there is sufficient texture for edge following.
float	actfast_short_step	Step size to take when there is an edge to be followed.
uint8_t	corner_method	Method to use for determining where the corners are.
bool	derotation	Derotation switched on or off (depended on the quality of the gyroscope measurement)
float	derotation_correction_factor_x	Correction factor for derotation in x axis, determined from a fit from the gyros and flow rotation. (wrong FOV, camera not in center)
float	derotation_correction_factor_y	Correction factor for derotation in Y axis, determined from a fit from the gyros and flow rotation. (wrong FOV, camera not in center)
bool	fast9_adaptive	Whether the FAST9 threshold should be adaptive.
uint16_t	fast9_min_distance	Minimum distance in pixels between corners.
uint8_t	fast9_num_regions	The number of regions of interest the image is split into.
uint16_t	fast9_padding	Padding used in FAST9 detector.
bool	fast9_region_detect	Decides whether to detect fast9 corners in specific regions of interest or the whole image (only for feature management)
struct point_t *	fast9_ret_corners	Corners.
uint16_t	fast9_rsize	Amount of corners allocated.
uint8_t	fast9_threshold	FAST9 corner detection threshold.
bool	feature_management	Decides whether to keep track corners in memory for the next frame instead of re-detecting every time.
bool	got_first_img	If we got a image to work with.
struct image_t	img_gray	Current gray image frame.
bool	just_switched_method	Boolean to check if methods has been switched (for reinitialization)
uint8_t	max_iterations	The maximum amount of iterations the Lucas Kanade algorithm should do.
uint16_t	max_track_corners	Maximum amount of corners Lucas Kanade should track.
bool	median_filter	Decides to use a median filter on the velocity.
uint8_t	method	Method to use to calculate the optical flow.
struct image_t	prev_img_gray	Previous gray image frame.
uint8_t	pyramid_level	Number of pyramid levels used in Lucas Kanade algorithm (0 == no pyramids used)
uint16_t	resolution_factor	The resolution in EdgeFlow to determine the Divergence.
uint16_t	search_distance	Search distance for blockmatching alg.
bool	show_flow	Whether to draw the flow vectors on the image. Watch out! This changes the image as will be received by subsequent processing steps.
uint16_t	subpixel_factor	The amount of subpixels per pixel.
uint8_t	threshold_vec	The threshold in x, y subpixels which the algorithm should stop.
bool	track_back	Whether to track flow vectors back to the previous image, in order to check if the back-tracked flow leads to the original corner position.
uint16_t	window_size	Window size for the blockmatching algorithm (general value for all methods)

Macro Definition Documentation

#define FAST9_MAX_CORNERS 512

Definition at line 85 of file opticflow_calculator.h.

Referenced by opticflow_calc_init().

Function Documentation

bool calc_edgeflow_tot	(	struct opticflow_t *	opticflow,
		struct image_t *	img,
		struct opticflow_result_t *	result
	)

Run the optical flow with EDGEFLOW on a new image frame.

Parameters

[in]	*opticflow	The opticalflow structure that keeps track of previous images
[in]	*state	The state of the drone
[in]	*img	The image frame to calculate the optical flow from
[out]	*result	The optical flow result
	computation	successful

Definition at line 815 of file opticflow_calculator.c.

Referenced by opticflow_calc_frame().

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bool calc_fast9_lukas_kanade	(	struct opticflow_t *	opticflow,
		struct image_t *	img,
		struct opticflow_result_t *	result
	)

Run the optical flow with fast9 and lukaskanade on a new image frame.

Parameters

[in]	*opticflow	The opticalflow structure that keeps track of previous images
[in]	*state	The state of the drone
[in]	*img	The image frame to calculate the optical flow from
[out]	*result	The optical flow result

Returns: Was optical flow successful

Definition at line 298 of file opticflow_calculator.c.

Referenced by opticflow_calc_frame().

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void kalman_filter_opticflow_velocity	(	float *	velocity_x,
		float *	velocity_y,
		float *	acceleration_measurement,
		float	fps,
		float *	measurement_noise,
		float	process_noise,
		bool	reinitialize_kalman
	)

bool opticflow_calc_frame	(	struct opticflow_t *	opticflow,
		struct image_t *	img,
		struct opticflow_result_t *	result
	)

Run the optical flow on a new image frame.

Parameters

[in]	*opticflow	The opticalflow structure that keeps track of previous images
[in]	*state	The state of the drone
[in]	*img	The image frame to calculate the optical flow from
[out]	*result	The optical flow result