apriltag_js.h File Reference

Definitions for the apriltag detector. More...

#include "apriltag.h"
#include "apriltag_pose.h"
#include "str_json.h"

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Macros
#define	STR_DET_LEN   1500

Functions
int	atagjs_init ()
	Init the apriltag detector with given family and default options default options: quad_decimate=2.0; quad_sigma=0.0; nthreads=1; refine_edges=1; return_pose=1. More...
int	atagjs_destroy ()
	Releases resources. More...
int	atagjs_set_detector_options (float decimate, float sigma, int nthreads, int refine_edges, int max_detections, int return_pose, int return_solutions)
	Sets the given detector options. More...
int	atagjs_set_pose_info (double fx, double fy, double cx, double cy)
	Sets camera intrinsics (in pixels) for tag pose estimation. More...
uint8_t *	atagjs_set_img_buffer (int width, int height, int stride)
	Creates/changes size of the image buffer where we receive the images to process. More...
t_str_json *	atagjs_detect ()
	Detect tags in image stored in the buffer (g_img_buf) More...

Detailed Description

Definitions for the apriltag detector.

Use apriltag library to implement a detector that runs in the browser using WASM

Copyright (C) Wiselab CMU.

Date

July, 2020

Function Documentation

atagjs_destroy()

int atagjs_destroy

(

)

Releases resources.

Returns

0=success

atagjs_detect()

t_str_json* atagjs_detect

(

)

Detect tags in image stored in the buffer (g_img_buf)

Returns

pointer to str_json structure. The data in this memory location must be consumed before the next call to detect()

Warning

caller is responsible for putting grayscale image pixels in the input buffer (g_img_buf)

caller should not release return pointer (it's reused at every detect() call); data returned must be consumed before the next call to detect()

atagjs_init()

int atagjs_init

(

)

Init the apriltag detector with given family and default options default options: quad_decimate=2.0; quad_sigma=0.0; nthreads=1; refine_edges=1; return_pose=1.

See also

set_detector_options for meaning of options

Returns

0=success; -1 on failure

atagjs_set_detector_options()

int atagjs_set_detector_options	(	float	decimate,
		float	sigma,
		int	nthreads,
		int	refine_edges,
		int	max_detections,
		int	return_pose,
		int	return_solutions
	)

Sets the given detector options.

Parameters

decimate	Decimate input image by this factor
sigma	Apply low-pass blur to input; negative sharpens
nthreads	Use this many CPU threads
refine_edges	Spend more time trying to align edges of tags
max_detections	Maximum number of detections to return (0=no max)
return_pose	Detect returns pose of detected tags (0=does not return pose; returns pose otherwise)
return_solutions	Detect returns details about both solutions of the pose estimation, if available

Returns

0=success

atagjs_set_img_buffer()

uint8_t* atagjs_set_img_buffer	(	int	width,
		int	height,
		int	stride
	)

Creates/changes size of the image buffer where we receive the images to process.

Parameters

width	Width of the image
height	Height of the image
stride	How many pixels per row (=width typically)

Returns

the pointer to the image buffer

Warning

caller of detect is responsible for putting grayscale image pixels in this buffer

atagjs_set_pose_info()

int atagjs_set_pose_info	(	double	fx,
		double	fy,
		double	cx,
		double	cy
	)

Sets camera intrinsics (in pixels) for tag pose estimation.

Parameters

fx	x focal lenght in pixels
fy	y focal lenght in pixels
cx	x principal point in pixels
cy	y principal point in pixels

Returns

0=success