GPS_TCX_data            The GPS-TCX data as a formated data.table
crop_DEM                Function to crop the AOI from the downloaded
                        DEM .tif file
extend_AOI_buffer       Extract the sf-object and raster extent based
                        on a buffer (in meters)
fitbit_data_type_by_date
                        Process pre-downloaded Fitbit data for Blood
                        Oxygen Saturation, Heart Rate Variability,
                        Breathing Rate, Temperature and Cardio Fitness
                        Score (or VO2 Max) by Date
gps_lat_lon_to_LINESTRING
                        Convert the GPS, TCX data to a LINESTRING
heart_rate_heatmap      Heart Rate Intraday Heatmap (by extracting the
                        'min.', 'median' and 'max.' values of the day)
heart_rate_time_series
                        heart rate activity time series
heart_rate_variability_sleep_time
                        Heart Rate Variability during Sleep Time (the
                        root mean square of successive differences)
leafGL_point_coords     Create a Leafet map (including information
                        pop-ups)
rayshader_3d_DEM        Rayshader 3-dimensional using the Copernicus
                        DEM elevation data
sleep_single_day        Sleep Data of single day
sleep_time_series       Sleep Data Time Series
