Depth Estimation Using Polarizer-Free Liquid Crystal Lens

Fig. 2. Numerical analysis of error indicator S. (a) Comparison of S distributions for natural light and extraordinary light in frequency domain; (b) relationship between error indicator S and fuzzy spot radius when $v = 0.8 v_{m a x}$ and R is different

Download full size

Fig. 3. Relationship between power of liquid crystal lens and voltage difference. (a) Interference image; (b) relationship between fitted power of liquid crystal lens (negative values mean negative lens) and voltage difference

Download full size

Fig. 4. Relatively large errors in initial calculation results. (a) Near-focus image; (b) far-focus image; (c) estimated depth; (d) ground truth

Download full size

Fig. 5. Foreground depth estimation affects background depth estimation. Dashed line is a reference line for convenience of comparison. (a) Near-focus image; (b) far-focus image; (c) foreground depth estimation affects background depth estimation (sliding window size is $63 \times 63$ ); (d) as sliding window size increases ( $127 \times 127$ ), adverse effect of foreground on background intensifies

Download full size

Fig. 6. Confidence after correction. (a) Far-focus image; (b) near-focus image; (c) estimated depth; (d) according to original confidence, retain 53% high-confidence data (dark data in image is excluded data); ( e) according to improved confidence, retain 53% high-confidence data; (f) ground truth; (g) depth completion of (d); (h) depth completion of (e)

Download full size

Fig. 7. Effect comparison of depth completion methods. (a) Semantic segmentation + Laplacian matting; (b) Laplacian matting; (c) Markov random field; (d) ground truth

Download full size

Fig. 8. Effect comparison of depth estimation without polarizer and with polarizer for slop scenes. First and second rows are slop scenes with polarizer and without polarizer, respectively. First and second columns are images of liquid crystal lens with optical power of $-$ 0.70 $m^{- 1}$ and 1.86 $m^{- 1}$ , respectively. Third column is depth estimation result. Fourth column is ground truth

Download full size

Fig. 9. Effect comparison of depth estimation without polarizer and with polarizer for plane scenes. First and second rows are plane scenes with polarizer and without polarizer, respectively. First and second columns are images of liquid crystal lens with optical power of 0 and 0.95 $m^{- 1}$ , respectively. Third column is depth estimation result. Fourth column is ground truth

Download full size

Fig. 10. Comparison of input images. From left to right are images formed by liquid crystal lens with optical power of -1, -0.7, and 1.86 $m^{- 1}$ , respectively. First row are images with polarizer and second row are images without polarizer

Download full size

Fig. 11. Optimal depth estimation for different depth ranges. Depth ranges corresponding to first and second rows are doll, nesting doll, plush toy, zebra, and background. Third and fourth rows correspond to true depth value, global optimal initial estimation value, and depth estimation values after error elimination and depth completion. First and third rows are results with polarizer. Second and fourth rows are results without polarizer

Download full size

Table 1. Adjustment values of optical power of liquid crystal lens
View table
Table 1. Adjustment values of optical power of liquid crystal lens
Number $P_{l c} / m^{- 1}$ Number $P_{l c} / m^{- 1}$ Number $P_{l c} / m^{- 1}$ Number $P_{l c} / m^{- 1}$
1 $-$ 2.00 5 $-$ 0.70 9 0.64 13 1.86
2 $-$ 1.65 6 $-$ 0.37 10 0.95
3 $-$ 1.36 7 0 11 1.24
4 $-$ 1.00 8 0.31 12 1.56

Table 2. Optimal depth estimation parameters for slope and plane scenes (P means with polarizer and NP means without polarizer in Type column)
View table
Table 2. Optimal depth estimation parameters for slope and plane scenes (P means with polarizer and NP means without polarizer in Type column)
Scene Type $d_{a v g} / m$ $P_{l c}^{(1)} / m^{- 1}$ $P_{l c}^{(2)} / m^{- 1}$ $R M S E$ /m $A W T_{1.25}$ $R_{e 1}$ $R_{e 2}$
Slop P 0.77 $-$ 0.37 1.56 0.07 1.00 12.83 9.41
NP 0.77 $-$ 0.37 1.56 0.05 1.00 12.83 9.41
Plane P 0.90 0.31 0.64 0.02 1.00 2.78 1.03
NP 0.90 0 0.95 0.02 1.00 6.35 4.60

Table 3. Depth ranges for different objects
View table
Table 3. Depth ranges for different objects
Object Depth /m
Doll 0.38
Nesting doll 0.70
Plush toy 0.99
Zebra 1.27
Background 1.96

Table 4. Effect comparison of optimal depth estimation for different depth ranges under extraordinary light and natural light. First sub-row in each row represents extraordinary light, second sub-row in each row represents natural light, and bold indicates better effect

View table

Table 4. Effect comparison of optimal depth estimation for different depth ranges under extraordinary light and natural light. First sub-row in each row represents extraordinary light, second sub-row in each row represents natural light, and bold indicates better effect

Object	$N$	$d_{m i n} / m$	$d_{m a x} / m$	$d_{a v g} / m$	$\begin{array}{l} d_{s t d} / \\ (10^{- 3} m) \end{array}$	$P_{l c}^{(1)} / m^{- 1}$	$P_{l c}^{(2)} / m^{- 1}$	$R_{e 1}$	$R_{e 2}$	$R_{o}$	$R M S E$	$A W T_{1.25}$
Doll	118214	0.20	0.49	0.38	4.5	1.56	1.86	5.85	2.39	—	0.11	0.94
Doll	118214	0.20	0.49	0.38	4.5	0	1.86	23.82	2.39	23.82	0.24	0.62
Nesting doll	56919	0.49	0.78	0.70	7.4	0.64	0.95	2.59	0.99	—	0.03	1.00
Nesting doll	56919	0.49	0.78	0.70	7.4	0	1.56	9.96	8.02	9.96	0.08	0.96
Plushtoy	26077	0.78	1.06	0.99	8.9	0.31	0.64	1.69	2.12	—	0.05	1.00
Plushtoy	26077	0.78	1.06	0.99	8.9	0.31	0.64	1.69	2.12	5.26	0.05	1.00
Zebra	44870	1.06	1.35	1.27	39.8	0	0.31	2.65	0.92	—	0.08	1.00
Zebra	44870	1.06	1.35	1.27	39.8	$-$ 0.37	0.95	6.91	8.30	2.65	0.07	1.00
Background	67370	1.93	2.21	1.96	10.4	$-$ 0.37	0.31	3.74	4.10	—	0.11	0.99
Background	67370	1.93	2.21	1.96	10.4	$-$ 0.37	0.31	3.74	4.10	0.53	0.12	0.98
All	314818	0.20	2.50	0.96	608.0	$-$ 0.70	1.86	13.65	15.85	—	0.43	0.50
All	314818	0.20	2.50	0.96	608.0	$-$ 1.00	1.86	17.11	15.85	5.59	0.32	0.69
All	314818	0.20	2.50	0.96	608.0	$-$ 0.70	1.86	13.65	15.85	—	0.40	0.51
All	314818	0.20	2.50	0.96	608.0	$-$ 1.00	1.86	17.11	15.85	5.59	0.19	0.87

Tools

Get Citation

Copy Citation Text

Wenjie Lai, Zhiqiang Liu, Tao Sun, Xiao Hu. Depth Estimation Using Polarizer-Free Liquid Crystal Lens[J]. Acta Optica Sinica, 2023, 43(14): 1415002

Download Citation

EndNote(RIS)BibTex Plain Text

Set citation alerts for article

Save article for my favorites

Paper Information

Category: Machine Vision

Received: Feb. 16, 2023

Accepted: Mar. 24, 2023

Published Online: Jul. 13, 2023

The Author Email: Xiao Hu (huxiao@uestc.edu.cn)

DOI:10.3788/AOS230562

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Adjustment values of optical power of liquid crystal lens

Table 1. Adjustment values of optical power of liquid crystal lens

Table 2. Optimal depth estimation parameters for slope and plane scenes (P means with polarizer and NP means without polarizer in Type column)

Table 2. Optimal depth estimation parameters for slope and plane scenes (P means with polarizer and NP means without polarizer in Type column)

Table 3. Depth ranges for different objects

Table 3. Depth ranges for different objects

Table 4. Effect comparison of optimal depth estimation for different depth ranges under extraordinary light and natural light. First sub-row in each row represents extraordinary light, second sub-row in each row represents natural light, and bold indicates better effect

Table 4. Effect comparison of optimal depth estimation for different depth ranges under extraordinary light and natural light. First sub-row in each row represents extraordinary light, second sub-row in each row represents natural light, and bold indicates better effect