Automated characterization techniques and testbeds for event-based cameras

Abstract

Event-based camera (EBC) technology shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate development of new characterization techniques to quantify performance and assess if the EBC technology produces benefits relative to traditional imaging sensors. Here we present progress on development of basic sensor performance modeling and test capabilities for commercial-off-the-shelf visible EBCs. Laboratory characterization techniques include noise level as a function of static scene light level (termed <i>background activity</i>) and EBC <i>temporal contrast</i> response to dynamic signals. Initial environmental tests of the Prophesee PPS3MVCD event-based sensor found several addressable areas of concern but identified no showstoppers that would prevent use of this device in a high-reliability aerospace application. Two independent radiation tolerance test efforts, one for the PPS3MVCD and another for the iniVation DAVIS346 EBC (both based on 180 nm CMOS technology), indicate functional issues for total ionizing dose (TID) of greater than 30 krad(Si), and show background activity increasing with TID. However, no significant change in contrast response was observed. One DAVIS346 exhibited functional failure following final gamma radiation dose from 20 krad(Si) to 50 krad(Si), and the readout saturated during doses dominated by negative-polarity events (by a factor of 10 or greater). A second DAVIS346 locked-up during proton dose but recovered normal operation following a brief rest period and power cycling. DAVIS346 pixels include both change detection (DVS) and standard grayscale frames (APS) functionalities – driven by a single photodiode; results show a 70% increase in dark current and 23% increase in dark event noise after proton exposure to 20 krad(Si). As new versions of EBC technology are developed for infrared wavelengths, we anticipate these characterization techniques will be largely translatable to IR EBCs.