utils.h

#ifndef UTILS_H
#define UTILS_H

#include <string>
#include <iostream>
#include <dirent.h>
#include <errno.h>
#include "structs.h"
#include "camera.h"
#include "opencv2/opencv.hpp"
#include "opencv2/aruco/charuco.hpp"

using namespace std;
using namespace cv;

class Utils
{
public:
    // Returns if a file exists in file system.
    static bool FileExists ( const string& filename );

    // Returns if a folder exists in file system.
    static bool FolderExists ( const string& folderName );

    // Draws a frame on a named window with/without detected corners and/or reprojected corners.
    static void ShowFrameInWindow ( const string& window_name, const Frame& frame, const bool draw_detected, const bool draw_reprojected );

    // Saves a frame to file system with/without detected corners and/or reprojected corners.
    static void SaveFrame ( const string& folder, const Frame& frame, const bool draw_detected, const bool draw_reprojected, const bool save_info );

    // Collects points from vector based on ids to a N x 1 x c(3) Mat.
    // Note that opencv charuco return points coordinates with y+ up and x+ right, and start from (size, size).
    static Mat GetCharucoBoardCornersMatFromVector ( const Mat& corner_ids, const vector<Point3f>& point_vector );

    // Swap x and y coordinate for applying coordinates system used in paper.
    // Note that input is assumed to be single channel and single point in each row.
    static Mat SwapPointsXandY ( const Mat& points );

    // Return +1 if positive, -1 if negative, 0 otherwise.
    static int Sign ( const double value );

    // Evaluates polynomial equations.
    static double EvaluatePolyEquation ( const double* coefficients, const int n, const double x );

    // Fetches rodrigues rotation vector and translation vector from 3 x 4 transform matrix.
    static void GetRAndTVectorsFromTransform ( const Mat& transform, Mat* r_mat, Mat* t_mat );

    // Forms up 3 x 4 transform matrix from rotation vector and translation vector.
    static void GetTransformFromRAndTVectors ( const Mat& r_mat, const Mat& t_mat, Mat* transform );

    // Gets Cayley vector and translation vector from 3 x 4 transform matrix.
    static void GetCAndTVectorsFromTransform ( const Mat& transform, Mat* c_mat, Mat* t_mat );

    // Gets Cayley vector vector from 3 x 3 rotation matrix.
    static void GetCVectorFromRotation ( const Mat& rotation, Mat* c_mat );

    // Get transfrom matrix 4 x 4 from transfrom 3 x 4.
    static Mat GetTransform44From34 ( const Mat& transform );

    // Get inversed transform matrix.
    static Mat InvertTransform ( const Mat& transform );

    // Reprojects the board corners in the frame based on input intrinsic and extrinsic parameters.
    static void ReprojectCornersInFrame ( const double* intrinsics, const double* rotation_vector_data, const double* translation_vector_data,
                                          const Mat& flatten_board_corners, Mat* reprojected_corners );

    // Reprojects a single board corner in the frame based on input instrinsic and extrinsic parameters.
    static void ReprojectSingleCorner ( const double* intrinsics, const double* rotation_vector_data, const double* translation_vector_data,
                                        const Vec3d& board_corner, Vec2d* reprojected_corner );
};

#endif // UTILS_H