Table 3 Comparison of depth measurements among different methods (unit: cm)
Specimen | Visual inspection | Impact-echo method | Non-contact video-based method |
|---|---|---|---|
12-1# | 5.95 | 6.24 | 6.04 |
12-2# | 5.02 | 5.61 | 5.23 |
12-3# | 6.34 | 7.18 | 6.58 |
16-1# | 5.78 | 6.22 | 5.92 |
16-2# | 6.45 | 7.88 | 6.71 |
16-3# | 5.90 | 7.26 | 6.24 |