Figure 2
From: Technical accuracy of optical and the electromagnetic tracking systems
The 3D error surfaces of the OTS (A) and the EMTS (B). The trend of error for both modalities is seen with the changes of the shading within the surfaces. The dark blue color represents 0 mm error and dark red the highest error. The orientation of the phantom with respect to the navigator is such that the optical camera pair of the OTS (A) is located perpendicularly to the right front edge and the EM field generator of the EMTS (B) perpendicularly to the right front edge, in both cases at the middle level.