Fig. 4
From: Classification of COVID-19 electrocardiograms by using hexaxial feature mapping and deep learning
ECG electrode location representations: a 3D representation of hexaxial and horizontal reference systems of 12-lead ECG acquisition, b 2D mapping of 3D hexaxial (limb leads) and horizontal (precordial leads) reference systems on the coronal plane; and an example of hexaxial feature mapping by using GLCM energies for c No-Finding class (Report Number: 182) and d COVID-19 class (Report Number: 16)