geo.h

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/**
 * @file geo.h
 *
 * Definition of geo / math functions to perform geodesic calculations
 *
 * @author Thomas Gubler <thomasgubler@student.ethz.ch>
 * @author Julian Oes <joes@student.ethz.ch>
 * @author Lorenz Meier <lm@inf.ethz.ch>
 * @author Anton Babushkin <anton.babushkin@me.com>
 * Additional functions - @author Doug Weibel <douglas.weibel@colorado.edu>
 */

#pragma once

#include <stdbool.h>
#include <stdint.h>

static constexpr float CONSTANTS_ONE_G = 9.80665f;                      // m/s^2

static constexpr float CONSTANTS_STD_PRESSURE_PA = 101325.0f;                   // pascals (Pa)
static constexpr float CONSTANTS_STD_PRESSURE_KPA = CONSTANTS_STD_PRESSURE_PA / 1000.0f;    // kilopascals (kPa)
static constexpr float CONSTANTS_STD_PRESSURE_MBAR = CONSTANTS_STD_PRESSURE_PA / 100.0f;    // Millibar (mbar) (1 mbar = 100 Pa)

static constexpr float CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C = 1.225f;                // kg/m^3
static constexpr float CONSTANTS_AIR_GAS_CONST = 287.1f;                    // J/(kg * K)
static constexpr float CONSTANTS_ABSOLUTE_NULL_CELSIUS = -273.15f;              // °C

static constexpr double CONSTANTS_RADIUS_OF_EARTH = 6371000;                    // meters (m)
static constexpr float  CONSTANTS_RADIUS_OF_EARTH_F = CONSTANTS_RADIUS_OF_EARTH;        // meters (m)

static constexpr float CONSTANTS_EARTH_SPIN_RATE = 7.2921150e-5f;               // radians/second (rad/s)


// XXX remove
struct crosstrack_error_s {
    bool past_end;      // Flag indicating we are past the end of the line/arc segment
    float distance;     // Distance in meters to closest point on line/arc
    float bearing;      // Bearing in radians to closest point on line/arc
} ;

/* lat/lon are in radians */
struct map_projection_reference_s {
    uint64_t timestamp;
    double lat_rad;
    double lon_rad;
    double sin_lat;
    double cos_lat;
    bool init_done;
};

struct globallocal_converter_reference_s {
    float alt;
    bool init_done;
};

/**
 * Checks if global projection was initialized
 * @return true if map was initialized before, false else
 */
bool map_projection_global_initialized();

/**
 * Checks if projection given as argument was initialized
 * @return true if map was initialized before, false else
 */
bool map_projection_initialized(const struct map_projection_reference_s *ref);

/**
 * Get the timestamp of the global map projection
 * @return the timestamp of the map_projection
 */
uint64_t map_projection_global_timestamp(void);

/**
 * Get the timestamp of the map projection given by the argument
 * @return the timestamp of the map_projection
 */
uint64_t map_projection_timestamp(const struct map_projection_reference_s *ref);

/**
 * Writes the reference values of the global projection to ref_lat and ref_lon
 * @return 0 if map_projection_init was called before, -1 else
 */
int map_projection_global_reference(double *ref_lat_rad, double *ref_lon_rad);

/**
 * Writes the reference values of the projection given by the argument to ref_lat and ref_lon
 * @return 0 if map_projection_init was called before, -1 else
 */
int map_projection_reference(const struct map_projection_reference_s *ref, double *ref_lat_rad, double *ref_lon_rad);

/**
 * Initializes the global map transformation.
 *
 * Initializes the transformation between the geographic coordinate system and
 * the azimuthal equidistant plane
 * @param lat in degrees (47.1234567°, not 471234567°)
 * @param lon in degrees (8.1234567°, not 81234567°)
 */
int map_projection_global_init(double lat_0, double lon_0, uint64_t timestamp);

/**
 * Initializes the map transformation given by the argument.
 *
 * Initializes the transformation between the geographic coordinate system and
 * the azimuthal equidistant plane
 * @param lat in degrees (47.1234567°, not 471234567°)
 * @param lon in degrees (8.1234567°, not 81234567°)
 */
int map_projection_init_timestamped(struct map_projection_reference_s *ref, double lat_0, double lon_0, uint64_t timestamp);

/**
 * Initializes the map transformation given by the argument and sets the timestamp to now.
 *
 * Initializes the transformation between the geographic coordinate system and
 * the azimuthal equidistant plane
 * @param lat in degrees (47.1234567°, not 471234567°)
 * @param lon in degrees (8.1234567°, not 81234567°)
 */
int map_projection_init(struct map_projection_reference_s *ref, double lat_0, double lon_0);

/**
 * Transforms a point in the geographic coordinate system to the local
 * azimuthal equidistant plane using the global projection
 * @param x north
 * @param y east
 * @param lat in degrees (47.1234567°, not 471234567°)
 * @param lon in degrees (8.1234567°, not 81234567°)
 * @return 0 if map_projection_init was called before, -1 else
 */
int map_projection_global_project(double lat, double lon, float *x, float *y);

/* Transforms a point in the geographic coordinate system to the local
 * azimuthal equidistant plane using the projection given by the argument
* @param x north
* @param y east
* @param lat in degrees (47.1234567°, not 471234567°)
* @param lon in degrees (8.1234567°, not 81234567°)
* @return 0 if map_projection_init was called before, -1 else
*/
int map_projection_project(const struct map_projection_reference_s *ref, double lat, double lon, float *x, float *y);

/**
 * Transforms a point in the local azimuthal equidistant plane to the
 * geographic coordinate system using the global projection
 *
 * @param x north
 * @param y east
 * @param lat in degrees (47.1234567°, not 471234567°)
 * @param lon in degrees (8.1234567°, not 81234567°)
 * @return 0 if map_projection_init was called before, -1 else
 */
int map_projection_global_reproject(float x, float y, double *lat, double *lon);

/**
 * Transforms a point in the local azimuthal equidistant plane to the
 * geographic coordinate system using the projection given by the argument
 *
 * @param x north
 * @param y east
 * @param lat in degrees (47.1234567°, not 471234567°)
 * @param lon in degrees (8.1234567°, not 81234567°)
 * @return 0 if map_projection_init was called before, -1 else
 */
int map_projection_reproject(const struct map_projection_reference_s *ref, float x, float y, double *lat, double *lon);

/**
 * Get reference position of the global map projection
 */
int map_projection_global_getref(double *lat_0, double *lon_0);

/**
 * Initialize the global mapping between global position (spherical) and local position (NED).
 */
int globallocalconverter_init(double lat_0, double lon_0, float alt_0, uint64_t timestamp);

/**
 * Checks if globallocalconverter was initialized
 * @return true if map was initialized before, false else
 */
bool globallocalconverter_initialized(void);

/**
 * Convert from global position coordinates to local position coordinates using the global reference
 */
int globallocalconverter_tolocal(double lat, double lon, float alt, float *x, float *y, float *z);

/**
 * Convert from local position coordinates to global position coordinates using the global reference
 */
int globallocalconverter_toglobal(float x, float y, float z,  double *lat, double *lon, float *alt);

/**
 * Get reference position of the global to local converter
 */
int globallocalconverter_getref(double *lat_0, double *lon_0, float *alt_0);

/**
 * Returns the distance to the next waypoint in meters.
 *
 * @param lat_now current position in degrees (47.1234567°, not 471234567°)
 * @param lon_now current position in degrees (8.1234567°, not 81234567°)
 * @param lat_next next waypoint position in degrees (47.1234567°, not 471234567°)
 * @param lon_next next waypoint position in degrees (8.1234567°, not 81234567°)
 */
float get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);

/**
 * Creates a new waypoint C on the line of two given waypoints (A, B) at certain distance
 * from waypoint A
 *
 * @param lat_A waypoint A latitude in degrees (47.1234567°, not 471234567°)
 * @param lon_A waypoint A longitude in degrees (8.1234567°, not 81234567°)
 * @param lat_B waypoint B latitude in degrees (47.1234567°, not 471234567°)
 * @param lon_B waypoint B longitude in degrees (8.1234567°, not 81234567°)
 * @param dist distance of target waypoint from waypoint A in meters (can be negative)
 * @param lat_target latitude of target waypoint C in degrees (47.1234567°, not 471234567°)
 * @param lon_target longitude of target waypoint C in degrees (47.1234567°, not 471234567°)
 */
void create_waypoint_from_line_and_dist(double lat_A, double lon_A, double lat_B, double lon_B, float dist,
        double *lat_target, double *lon_target);

/**
 * Creates a waypoint from given waypoint, distance and bearing
 * see http://www.movable-type.co.uk/scripts/latlong.html
 *
 * @param lat_start latitude of starting waypoint in degrees (47.1234567°, not 471234567°)
 * @param lon_start longitude of starting waypoint in degrees (8.1234567°, not 81234567°)
 * @param bearing in rad
 * @param distance in meters
 * @param lat_target latitude of target waypoint in degrees (47.1234567°, not 471234567°)
 * @param lon_target longitude of target waypoint in degrees (47.1234567°, not 471234567°)
 */
void waypoint_from_heading_and_distance(double lat_start, double lon_start, float bearing, float dist,
        double *lat_target, double *lon_target);

/**
 * Returns the bearing to the next waypoint in radians.
 *
 * @param lat_now current position in degrees (47.1234567°, not 471234567°)
 * @param lon_now current position in degrees (8.1234567°, not 81234567°)
 * @param lat_next next waypoint position in degrees (47.1234567°, not 471234567°)
 * @param lon_next next waypoint position in degrees (8.1234567°, not 81234567°)
 */
float get_bearing_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);

void get_vector_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next, float *v_n, float *v_e);

void get_vector_to_next_waypoint_fast(double lat_now, double lon_now, double lat_next, double lon_next, float *v_n, float *v_e);

void add_vector_to_global_position(double lat_now, double lon_now, float v_n, float v_e, double *lat_res, double *lon_res);

int get_distance_to_line(struct crosstrack_error_s *crosstrack_error, double lat_now, double lon_now,
                  double lat_start, double lon_start, double lat_end, double lon_end);

int get_distance_to_arc(struct crosstrack_error_s *crosstrack_error, double lat_now, double lon_now,
                 double lat_center, double lon_center,
                 float radius, float arc_start_bearing, float arc_sweep);

/*
 * Calculate distance in global frame
 */
float get_distance_to_point_global_wgs84(double lat_now, double lon_now, float alt_now,
        double lat_next, double lon_next, float alt_next,
        float *dist_xy, float *dist_z);

/*
 * Calculate distance in local frame (NED)
 */
float mavlink_wpm_distance_to_point_local(float x_now, float y_now, float z_now,
        float x_next, float y_next, float z_next,
        float *dist_xy, float *dist_z);