Detecting Square Markers in Underwater Environments
Abstract
:1. Introduction
- a new method for generating synthetic images of markers in underwater conditions;
- a new algorithm for the detection of square markers that is adapted for bad visibility in underwater environments;
- comparison of this algorithm with other state-of-the-art algorithms on synthetically-generated images and on real images.
Related Work
2. Marker Detection and Image-Improving Algorithms
2.1. ARUco, ARUco3, and AprilTag2
2.2. Real-Time Algorithms Improving Underwater Images
2.3. Detection of Markers under Water
Algorithm 1: Pseudocode of the algorithm for computing the brightness mask, the noise mask, and the final mask. |
Input: Grey scale image whose mask is to be computed, threshold for brightness mask , threshold for noise mask |
Output: Brightness and noise masks and |
← image of one fourth of the size of with minimums of pixels of ; |
← image of one fourth of the size of with maximums of pixels of ; |
minimum of surrounding pixels of ; |
maximum of surrounding pixels of ; |
; |
; |
; |
; |
Algorithm 2: Pseudocode of the algorithm for computing thresholds for the brightness mask and the noise mask. |
3. Generating Synthetic Images
4. Experiments with Synthetically-Generated Images
4.1. Reference with Good Visual Conditions
4.2. Bad Visibility Conditions
4.3. Foggy Conditions and Markers at Different Distances
4.4. Glowing Markers
4.5. All Effects
Discussion of Synthetic Images
5. Evaluation of Real Underwater Images
5.1. Results of Underwater Tests
5.2. Discussion of Underwater Experiments
6. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Solution | ARUco | UWARUco Base | UWARUco Masked | ARUco3 Normal | ARUco3 Fast | ARUco3 VideoFast | AprilTag2 |
Detected markers (%) | 32.067 | 64.658 | 75.050 | 24.000 | 60.392 | 45.450 | 51.342 |
Detection time (ms) | 96.002 | 255.633 | 117.907 | 76.769 | 89.064 | 9.564 | 1220.796 |
Solution | ARUco Original | ARUco CLAHE | ARUco Deblur | ARUco WB | ARUco MBUWWB | ||
Detected markers (%) | 32.067 | 63.225 | 43.808 | 46.025 | 57.525 | ||
Detection time (ms) | 96.002 | 201.421 | 218.623 | 200.801 | 193.417 | ||
Solution | UWARUco Masked Original | UWARUco Masked CLAHE | UWARUco Masked Deblur | UWARUco Masked WB | UWARUco Masked MBUWWB | ||
Detected markers (%) | 75.050 | 79.525 | 58.500 | 77.992 | 77.358 | ||
Detection time (ms) | 117.907 | 128.644 | 141.740 | 128.436 | 117.376 |
Solution | ARUco | UWARUco Base | UWARUco Masked | ARUco3 Normal | ARUco3 Fast | ARUco3 VideoFast | AprilTag2 |
Detected markers (%) | 7.967 | 63.533 | 72.683 | 1.875 | 25.892 | 18.075 | 28.900 |
Detection time (ms) | 97.862 | 263.899 | 128.422 | 77.829 | 56.790 | 6.979 | 871.732 |
Solution | ARUco Original | ARUco CLAHE | ARUco Deblur | ARUco WB | ARUco MBUWWB | ||
Detected markers (%) | 7.967 | 42.417 | 19.767 | 19.783 | 21.342 | ||
Detection time (ms) | 97.862 | 200.967 | 219.783 | 206.210 | 195.214 | ||
Solution | UWARUco Masked Original | UWARUco Masked CLAHE | UWARUco Masked Deblur | UWARUco Masked WB | UWARUco Masked MBUWWB | ||
Detected markers (%) | 72.683 | 74.992 | 47.608 | 73.125 | 68.633 | ||
Detection time (ms) | 128.422 | 136.058 | 156.065 | 117.667 | 94.246 |
Nm: | Baiae1 | Nm: | Athens | Nm: | Constandis |
Lc: | Baiae, Italy | Lc: | Athens, Greece | Lc: | Limassol, Cyprus |
Tr: | High | Tr: | Moderate | Tr: | Moderate |
Dp: | 5–6 m | Dp: | 7–9 m | Dp: | 20–22 m |
Dv: | iPad Pro 9.7 inch | Dv: | GoPro camera | Dv: | GARMIN VIRB XE |
Rs: | 1920 × 1080 | Rs: | 1920 × 1080 | Rs: | 1920 × 1440 |
Cm: | MPEG-2 | Cm: | MPEG-4 | Cm: | MPEG-4 |
FL: | 30 fps, 85 s | FL: | 30 fps, 31 s | FL: | 24 fps, 160 s |
Nm: | Green Bay | Nm: | Villa | Nm: | Baiae2 |
Lc: | Green Bay, Cyprus | Lc: | Villa a Protiro, B., It. | Lc: | Baiae, Italy |
Tr: | Low | Tr: | Moderate | Tr: | Moderate |
Dp: | 7–9 m | Dp: | 5–6 m | Dp: | 5–6 m |
Dv: | NVIDIA SHIELD | Dv: | Samsung Galaxy S8 | Dv: | iPad Mini 2 |
Rs: | 1920 × 1080 | Rs: | 1920 × 1080 | Rs: | 1920 × 1080 |
Cm: | MPEG-4 | Cm: | no compression | Cm: | MPEG-4 |
FL: | 30 fps, 81 s | FL: | 30 fps, 141 s | FL: | 30 fps, 421 s |
Nm: | Epidauros | ||||
Lc: | Epidauros, Greece | ||||
Tr: | Low | ||||
Dp: | 4–6 m | ||||
Dv: | Sony FDR-X1000V | ||||
Rs: | 3840 × 2160 | ||||
Cm: | MPEG-4 | ||||
FL: | 24 fps, 180 s |
Solution | ARUco | UWARUco Base | UWARUco Masked | ARUco3 Normal | ARUco3 Fast | ARUco3 VideoFast | AprilTag2 | |
Baiae1 | # of markers | 467 | 6004 | 6223 | 36 | 2145 | 1893 | 5695 |
Time (ms) | 24.627 | 111.528 | 57.680 | 15.397 | 6.970 | 1.748 | 178.874 | |
Athens | # of markers | 5272 | 5913 | 5832 | 4877 | 5565 | 2610 | 5923 |
Time (ms) | 31.202 | 86.503 | 53.771 | 21.398 | 6.550 | 2.843 | 240.672 | |
Constandis | # of markers | 6981 | 6944 | 6878 | 6578 | 5382 | 4511 | 6332 |
Time (ms) | 39.010 | 139.514 | 65.565 | 25.030 | 6.672 | 5.446 | 327.887 | |
Green Bay | # of markers | 7964 | 7932 | 7594 | 7062 | 6347 | 5784 | 7332 |
Time (ms) | 27.531 | 74.712 | 49.915 | 18.040 | 10.537 | 5.288 | 222.003 | |
Villa | # of markers | 14,457 | 19,879 | 20,145 | 9947 | 14,316 | 12,589 | 20,082 |
Time (ms) | 75.747 | 140.659 | 62.872 | 58.266 | 6.700 | 2.368 | 323.005 | |
Baiae2 | # of markers | 13,829 | 15,932 | 14,976 | 12,466 | 8257 | 3869 | 14,577 |
Time (ms) | 34.552 | 83.614 | 55.093 | 21.535 | 4.563 | 1.672 | 230.910 | |
Epidauros | # of markers | 18,749 | 25,126 | 25,713 | 13,864 | 10,480 | 6340 | 21,628 |
Time (ms) | 181.441 | 425.286 | 252.327 | 152.590 | 23.575 | 4.692 | 1252.122 | |
Solution | ARUco Original | ARUco CLAHE | ARUco Deblur | ARUco WB | ARUco MBUWWB | |||
Baiae1 | # of markers | 467 | 3646 | 3857 | 4098 | 5140 | ||
Time (ms) | 24.627 | 38.064 | 80.560 | 43.370 | 47.475 | |||
Athens | # of markers | 5272 | 5504 | 5611 | 5640 | 5616 | ||
Time (ms) | 31.202 | 48.424 | 86.524 | 45.867 | 38.271 | |||
Constandis | # of markers | 6981 | 6279 | 6850 | 6737 | 6869 | ||
Time (ms) | 39.010 | 73.406 | 136.165 | 86.436 | 53.236 | |||
Green Bay | # of markers | 7964 | 6406 | 8355 | 7392 | 7896 | ||
Time (ms) | 27.531 | 49.000 | 84.394 | 50.442 | 35.355 | |||
Villa | # of markers | 14,457 | 18,981 | 18,958 | 19,029 | 19,398 | ||
Time (ms) | 75.747 | 138.263 | 178.143 | 114.494 | 45.239 | |||
Baiae2 | # of markers | 13,829 | 14,126 | 11,445 | 11,500 | 10,227 | ||
Time (ms) | 34.552 | 62.603 | 100.112 | 50.598 | 27.755 | |||
Epidauros | # of markers | 18,749 | 20,030 | 23,597 | 16,929 | 21,696 | ||
Time (ms) | 181.441 | 341.750 | 586.785 | 296.562 | 181.483 | |||
Solution | UWARUco Masked Original | UWARUco Masked CLAHE | UWARUco Masked Deblur | UWARUco Masked WB | UWARUco Masked MBUWWB | |||
Baiae1 | # of markers | 6223 | 6612 | 6081 | 6129 | 5605 | ||
Time (ms) | 57.680 | 64.902 | 93.618 | 64.998 | 55.866 | |||
Athens | # of markers | 5832 | 5806 | 5848 | 5831 | 5829 | ||
Time (ms) | 53.771 | 60.742 | 85.729 | 60.054 | 52.622 | |||
Constandis | # of markers | 6878 | 6702 | 6959 | 6749 | 6843 | ||
Time (ms) | 65.565 | 75.938 | 105.121 | 76.404 | 68.263 | |||
Green Bay | # of markers | 7594 | 6776 | 7464 | 7149 | 7599 | ||
Time (ms) | 49.915 | 56.289 | 78.405 | 56.515 | 51.390 | |||
Villa | # of markers | 20,145 | 20,281 | 19,400 | 20,225 | 20,258 | ||
Time (ms) | 62.872 | 82.574 | 114.332 | 65.231 | 61.647 | |||
Baiae2 | # of markers | 14,976 | 15,996 | 15,356 | 12,988 | 13,244 | ||
Time (ms) | 55.093 | 65.498 | 85.929 | 62.256 | 55.415 | |||
Epidauros | # of markers | 25,713 | 26,012 | 23,618 | 21,991 | 25,623 | ||
Time (ms) | 252.327 | 305.263 | 388.771 | 274.608 | 247.548 |
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Čejka, J.; Bruno, F.; Skarlatos, D.; Liarokapis, F. Detecting Square Markers in Underwater Environments. Remote Sens. 2019, 11, 459. https://doi.org/10.3390/rs11040459
Čejka J, Bruno F, Skarlatos D, Liarokapis F. Detecting Square Markers in Underwater Environments. Remote Sensing. 2019; 11(4):459. https://doi.org/10.3390/rs11040459
Chicago/Turabian StyleČejka, Jan, Fabio Bruno, Dimitrios Skarlatos, and Fotis Liarokapis. 2019. "Detecting Square Markers in Underwater Environments" Remote Sensing 11, no. 4: 459. https://doi.org/10.3390/rs11040459
APA StyleČejka, J., Bruno, F., Skarlatos, D., & Liarokapis, F. (2019). Detecting Square Markers in Underwater Environments. Remote Sensing, 11(4), 459. https://doi.org/10.3390/rs11040459