Multi-path compensation using multiple modulation frequencies in time of flight sensor
AssigneeHeptagon Micro Optics Pte. Ltd.
InventorsMatthias Schweizer, Thierry Oggier, Bernhard Buettgen
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Abstract
A method to compensate for multi-path in time-of-flight (TOF) three dimensional (3D) cameras applies different modulation frequencies in order to calculate/estimate the error vector. Multi-path in 3D TOF cameras might be caused by one of the two following sources: stray light artifacts in the TOF camera systems and multiple reflections in the scene. The proposed method compensates for the errors caused by both sources by implementing multiple modulation frequencies.
Claims10
A time of flight three dimensional imaging system, comprising:
- an illumination module that generates modulated light that is intensity modulated at a first frequency and at a second frequency;
- a sensor that detects the modulated light at the first frequency and at the second frequency;
- and
- a controller that generates a three dimensional image from the detected modulated light at the first frequency and at the second frequency and compensates for multipath error in the three dimensional image arising from the modulated light traveling an indirect path before detection based, at least in part, on a relationship between (i) a ratio of the generated modulated light at the first frequency and the generated modulated light at the second frequency, and (ii) a ratio of the detected modulated light at the first frequency and the detected modulated light at the second frequency.
A time of flight three dimensional imaging method, comprising:
- generating modulated light that is intensity modulated at a first frequency and at a second frequency;
- detecting the modulated light at the first frequency and at the second frequency;
- generating a three dimensional image from the detected modulated light;
- and
- compensating the three dimensional image for multipath error arising from the modulated light traveling an indirect path before detection based, at least in part, on a relationship between (i) a ratio of the generated modulated light at the first frequency and the generated modulated light at the second frequency, and (ii) a ratio of the detected modulated light at the first frequency and the detected modulated light at the second frequency.
Dependencies are inferred from the claim text.