US 11,921,217 B2
Method and device for the dynamic extension of a time-of-flight camera system
Thomas Kerstein, Kreuztal (DE)
Assigned to IFM Electronic GmbH, Essen (DE); and PMDTechnologies AG, Siegen (DE)
Appl. No. 18/025,241
Filed by IFM Electronic GmbH, Essen (DE); and PMDTechnologies AG, Siegen (DE)
PCT Filed Aug. 25, 2021, PCT No. PCT/EP2021/073456
§ 371(c)(1), (2) Date Mar. 8, 2023,
PCT Pub. No. WO2022/053313, PCT Pub. Date Mar. 17, 2022.
Claims priority of application No. 102020123671.9 (DE), filed on Sep. 10, 2020.
Prior Publication US 2023/0243974 A1, Aug. 3, 2023
Int. Cl. G01C 3/08 (2006.01); G01S 17/894 (2020.01)
CPC G01S 17/894 (2020.01) 4 Claims
OG exemplary drawing
 
1. A method for dynamic extension of raw phase images (M) of a time-of-flight camera system, in which the time-of-flight camera system determines distances (d) from a phase shift (Δφ) of emitted and received radiation,
wherein for the distance determination a plurality of raw phase images (M) are acquired at different phase positions (φvar) between illumination and receiver and are captured with different exposure times (texp1, texp2), comprising the steps of:
a) identifying non-valid, i.e. saturated, pixels and valid, i.e. non-saturated, pixels in the raw phase images (M),
b) calculating normalized raw phase images (M) by subtracting a fixed pixel offset (Fixed Pattern Noise (FPN)) from each raw phase image (M) and normalizing the image reduced by the fixed pixel offset (FPN) with the respective exposure time (texp1, texp2) according to

OG Complex Work Unit Math
c) calculating weighted and normalized raw phase images (M′) by multiplying the normalized raw phase images (M) with a respective weighting matrix (G) according to
M′(texp)=M′(texp)*Gtexp′
d) calculating a weighted and normalized high dynamic range (HDR) raw phase image (MHDR) for a respective phase position by adding the weighted normalized raw phase images M′ of the respective phase position and normalizing to the sum of the weighting matrices, according to

OG Complex Work Unit Math
e) calculating a high dynamic range (HDR) raw phase image (MHDR) by multiplying the weighted and normalized high dynamic range (HDR) raw phase image (MHDR) by one of the exposure times (texp1, texp2) and adding the fixed pixel offset, according to
MHDR=MHDR·texp1+FPN, and
f) providing the high dynamic range (HDR) raw phase image (MHDR) for a subsequent processing.