Apriltag Detection

#define TAG_LOCATION_TYPE_STRINGS {"unknown", "fixed","static","dynamic"}
#define N_TAG_LOCATION_TYPES    4
#define TAG_LOCATION_UNKNOWN    0
#define TAG_LOCATION_FIXED      1
#define TAG_LOCATION_STATIC     2
#define TAG_LOCATION_DYNAMIC    3
// max name length of a tag name
#define TAG_NAME_LEN 64

/**
 * describes an apriltag, aruco, or similar detection. Provides the tag's position and rotation
 * relative to the camera that detected it.
 *
 * This packet is 252 bytes long.
 */
typedef struct tag_detection_t{
    uint32_t magic_number;                  ///< Unique 32-bit number used to signal the beginning of a VIO packet while parsing a data stream.
    int32_t  id;                            ///< id number of the tag
    float    size_m;                        ///< size of the tag in meters
    int64_t  timestamp_ns;                  ///< timestamp at the middle of the frame exposure in monotonic time
    char     name[TAG_NAME_LEN];            ///< optional name of the tag
    int      loc_type;                      ///< location type
    float    T_tag_wrt_cam[3];              ///< location of the tag with respect to camera frame in meters.
    float    R_tag_to_cam[3][3];            ///< rotation matrix from tag frame to camera frame
    float    T_tag_wrt_fixed[3];            ///< only set if location type is LOCATION_FIXED
    float    R_tag_to_fixed[3][3];          ///< only set if location type is LOCATION_FIXED
    char     cam[MODAL_PIPE_MAX_DIR_LEN];   ///< camera pipe where the detection was made
    int      reserved;                      ///< reserved field
} __attribute__((packed)) tag_detection_t;

yocto:/$ voxl-configure-tag-detector -h

Start wizard with prompts:
voxl-configure-tag-detector

Shortcut configuration arguments for scripted setup.
factory_enable will reset the config file to factory defaults
before enabling the service.

voxl-configure-tag-detector disable
voxl-configure-tag-detector factory_disable
voxl-configure-tag-detector factory_enable
voxl-configure-tag-detector enable

show this help message:
voxl-configure-tag-detector help

yocto:/$ voxl-configure-tag-detector
Starting Wizard

Do you want to reset the config file to factory defaults?
1) yes
2) no
#? 1
wiping old config file
Creating new config file: /etc/modalai/voxl-tag-detector.conf
Created new empty json file: /etc/modalai/tag_locations.conf
The JSON tag location data was modified during parsing, saving the changes to disk

do you want to enable or disable voxl-tag-detector
1) enable
2) disable
#? 1
enabling  voxl-tag-detector systemd service
Created symlink from /etc/systemd/system/multi-user.target.wants/voxl-tag-detector.service to /etc/systemd/system/voxl-tag-detector.service.
starting  voxl-tag-detector systemd service
Done configuring voxl-tag-detector

yocto:/$ cat /etc/modalai/voxl-tag-detector.conf
/**
 * This file contains configuration parameters for voxl-tag-detector.
 * You can specify up to 3 cameras to do detection on simultaneously.
 * For the stereo camera pair, only the left camera is used.
 */
{
    "detector_0":     {
        "enable":           true,
        "input_pipe":       "tracking",
        "en_fast_mode":     true,
        "n_threads":        1,
        "en_undistortion":  true,
        "undistort_scale":  0.600000023841858,
        "overlay_name":     "tracking_tag_overlay",
        "lens_cal_file":    "/data/modalai/opencv_tracking_intrinsics.yml",
        "skip_n_frames":    5
    },
    "detector_1":    {
        "enable":           false,
        "input_pipe":       "stereo",
        "en_fast_mode":     true,
        "n_threads":        1,
        "en_undistortion":  true,
        "undistort_scale":  0.899999976158142,
        "overlay_name":     "stereo_tag_overlay",
        "lens_cal_file":    "/data/modalai/opencv_stereo_intrinsics.yml",
        "skip_n_frames":    5
    },
    "detector_2":    {
        "enable":           false,
        "input_pipe":       "extra",
        "en_fast_mode":     true,
        "n_threads":        1,
        "en_undistortion":  false,
        "undistort_scale":  1,
        "overlay_name":     "extra_tag_overlay",
        "lens_cal_file":    "/data/modalai/opencv_extra_intrinsics.yml",
        "skip_n_frames":    5
    }
}

yocto:/$ cat /etc/modalai/tag_locations.conf
/**
 * Apriltag Location Configuration File
 * This file is used by voxl-tag-detector
 *
 * A tag can be flagged by the user as fixed, static, or dynamic.
 *
 *  - fixed: The tag is at a known location in space as described by the
 *    T_tag_wrt_fixed vector and R_tag_to_fixed rotation matrix. These fixed
 *    tags are used by voxl-vision-px4 for apriltag relocalization.
 *
 *  - static: A static tag can be trusted to be static (not moving) but does not
 *    have a known location. For example, a landing pad.
 *
 *  - dynamic: A dynamic tag can be expected to be in motion such as an object
 *    to be tracked or followed dynamically.
 *
 *
 * If the tag is fixed then you must specify its location and rotation relative
 * to the fixed reference frame. Otherwise the translation and rotation
 * parameters can be ignored.
 *
 * The name parameter is currently only used for info prints but can be helpful
 * for the user to keep track of what tag is which.
 *
 * Each tag must have its size listed. Tags not listed will be assumed to have
 * size equal to the default_size.
 *
 * Currently only 36h11 apriltags are supported
 */
{
    "locations":    [{
            "id":          0,
            "name":        "default_name",
            "loc_type":    "unknown",
            "size_m":      0.40000000596046448,
            "T_tag_wrt_fixed":    [0, 0, 0],
            "R_tag_to_fixed":    [[0, -1, 0], [1, 0, 0], [0, 0, 1]]
        }],
    "default_size_m":      0.40000000596046448
}