Localization systems mostly make use of Global Navigation Satellite System (GNSS) and Inertial Measurement Units (IMUs). Nowadays, there are off-the-shelf complete navigation systems incorporating GNSS, IMU and magnetic compass for a footprint of only 2x2cm2 and a mass of 5 grams. However, there are areas where the GNSS signal is obscured (urban canyons, metallic structures, interferences with other systems, poor weather conditions) or even areas where the Earth's magnetic field is too disturbed to provide a reliable measurement. For autonomous vehicles, a reliable navigation system is necessary. To overcome the limitations of the current systems, we are currently developing an optical compass (Fig. 1) based on a bioinspired approach derived from behavioral studies on desert ants Cataglyphis. This small animal has indeed a dedicated area, called the dorsal rim area, in the dorsal part of the compound eye sensitive to the polarized light of the sky. Thanks to this sensitivity to polarization light, ants estimate their orientation with respect to the pattern of polarization of the sky and are able to combine it with other information for localization purposes with respect to their nest. Similarly, our objective is to develop a first prototype of an automotive-specific sensor (Fig. 1), and determine its limits outdoors in real conditions. Especially, we will study the effect of atmospheric conditions on both the accuracy and the stability of the measured optical heading measurement. We will use a division-of-focal-plane polarization-imaging sensor with a fisheye lens to mimic an ant’s eye (Fig. 1), in order to take snapshots of the skylight polarization pattern, then to deduce optically the vehicle’s heading and to compare it to GNSS or magnetic field-based compasses measurements.