Hybrid Sensing Approach for Coded Modulation Time-of-Flight Cameras
Armin Schonlieb1, Plank Hannes1, Christian Steger2, Gerald Holweg1 and Norbert Druml1
1Infineon Technologies Austria AG, Graz, Austria
2Graz University of Technology, Graz, Austria
aarminjosef.schoenlieb@infineon.com
bhannes.plank@infineon.com
cgerald.holweg@infineon.com
dnorbert.druml@infineon.com
ABSTRACT
In recent years, application Field such as industrial automation and indoor robot navigation increased the demand on reliable localization systems. Simultaneous mappung and localization systems often depend on depth imaging in order to reconstruct the scene.
Time-of-Flight sensors prove to be well suited for these application, however are impaired by different error sources. The measurement principle is based on measuring the phase and consequently the delay of emitted and reflected light. Specular surfaces can cause pixel saturation, while the periodicity of the measured phase leads to ambiguous distances. In this paper, we aim to solve these problems by proposing a new Time-of-Flight depth sensing approach. By combining the emerging coded modulation method with traditional depth sensing, we are able to unify the advantages of both methods. Images captured with coded modulation pixel response only within selected distance limits. In contrast tradional continuous wave Time-of-Flight imaging exhibits a superior signal-to-noise ratio. This method enables to mask erroneous distance measurements, allowing Time-of-Flight sensors to produce more reliable depth measurements and gain taction in the industrial environment.
As our evaluation shows, our method is able to remove the influence of specular surfaces, and is capable of masking ambiguous distance measurements. Furthermore, our approach improves the system behavior by enabling more robust exposure time control.
Keywords: Time-of-Flight, ToF, Coded modulation.
