Fig. 1. Image sequence
[36]. (a) 1; (b) 2; (c) 3; (d) 4; (e) 5; (f) 6
Fig. 2. Histogram of DR in Fig1. (a) 1m2; (b) 1m3; (c) 1m4; (d) 1m5; (e) 1m6
Fig. 3. Inliers and outliers in image pairs with zoom
[37]. (a) Image pairs of inliers; (b) distributions of inliers and outliers
Fig. 4. Histogram of neighbor inlier distance in Fig. 3. (a) Left image in Fig. 3; (b) right image in Fig. 3
Fig. 5. Flow chart of image matching model estimation based on inliers ratio promotion
Fig. 6. Identical distribution (ID) and non-identical distribution (NID). (a) ID; (b) NID
Fig. 7. Normal distribution of distance between inliers and outliers
Fig. 8. Location relationship between undetermined image pairs and inliers
Fig. 9. Comparison of time complexity between Ransac and proposed algorithm
Fig. 10. Identical distribution matching. (a) Evenly distributed on both images; (b) ; (c) ; (d) ; (e)
Fig. 11. Non-identical distribution matching. (a) Left centralization and right dispersion; (b) ; (c) ; (d) ; (e)
Fig. 12. Non-identical distributions matching. (a) Left dispersion and right centralization; (b) ; (c) ; (d) ; (e)
Fig. 13. Inliers ratio after data filtering
Fig. 14. Inliers growth rate
Fig. 15. Real images. (a) Wall; (b) Graf1; (c) Graf2; (d) Book; (e) Boat1; (f) Boat2; (g) Valbonne; (h) Bonhall
Fig. 16. Change of image pairs’ number
Fig. 17. Change of inliers ratio
Fig. 18. Comparisons based on homogr data set. (a) Inliers recalls with different distance errors; (b) inliers recalls with different time consumption
Fig. 19. Comparisons based on kusvod2 data set. (a) Inliers recalls with different distance errors; (b) inliers recalls with different time comsumption
Fig. 20. Inliers recalls of proposed method with different sparsity of matching points. (a) Wall; (b) Graf1; (c) Valbonne
Fig. 21. Real images. (a) Booksh; (b) Leafs; (c) Scene0722; (d) Scene0758; (e) Scene0743; (f) Plant; (g) Rotunda; (h) Bread & Toys; (i) Saint Heart
Fig. 22. Performance before inliers ratio promotion. (a) Number of pairs of correspondence obtained; (b) ratio of outlier residual; (c) time consumption
Fig. 23. Performance after inliers ratio promotion. (a) Number of pairs of correspondence obtained; (b) ratio of outlier residual; (c) time consumption
Input: pairs of correspondences: , Output: M pairs of correspondences after data filtering: , |
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Step1: Compute matrix according to Eq. (7), the size of is Step2: Compute the sums of all columns in , and get a data set , where , Step3: Reorder in ascend, so, a new data set is gotten: , in which, and Step4: Compute the average value of : , and then compute and , where, , , and satisfies the expression: Step5: Obtain threshold : Step6: Obtain M pairs of correspondences after , wheresatisfies the expression: |
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Table 1. Algorithm of inliers ratio promotion
Input: pairs of correspondences:; The number of iteration allowed: max itera;termination condition;the initial number of iteration: ; number of the minimum samples that model can be calculated:, 4 (homography), 7 or 8 (fundamental matrix) Output: The optimal model or multi models, and its or their inliers |
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Step1: Obtain the data set, which contains pairs of correspondences after data filtering as shown in Table 1:, Step2: , and sample pairs of correspondences from, and obtain the current hypothesis Step3: Taketo , and calculate the number of inliers which are fitted Step4: Judge whether the hypothesis meets with the termination condition, and whether the current number of iteration meets with max itera, either satisfied, go to Step5, otherwise, return to Step2 Step5: Obtain the optimal model or multi models and its or their inliers |
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Table 2. Random sample consensus algorithm based on proposed inliers ratio promotion
Input: pairs of correspondences:; threshold: ,which is user defined, the type value is 0.01; number of neighbors: , which is user defined, and lies in the range from 4 to 6 Output: |
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Step1: Obtain the data set , which contains pairs of correspondences aftering data filtering as shown in Table 1:,, and obtain pairs of correspondences which are filtered out:, Step2: Obtain inliers set from with any graph method, such as NMNET, OANET, PointCN, and SuperGlue, Step3: For each pair of correspondence in set :: 1) Obtain the neighbor inliers set that contains pairs of correspondence with the help of KNN: and , and calculate the distance from to each point of the set: and ; 2) Normalize the distances by Eq (8), calculateand by Eq (9); 3) Judge whether is not lager than , if satisfied,, and End |
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Table 3. Graph matching algorithm based on proposed inliers ratio promotion
Image | Wall | Graf1 | Graf2 | Book | Boat1 | Boat2 | Valbonne | Bonhall |
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Number of matched pairs | 993 | 2415 | 2415 | 1539 | 3151 | 3151 | 1991 | 1802 | Pixel | 500×350 | 800×640 | 800×640 | 600×450 | 850×680 | 850×680 | 512×768 | 490×653 | Inliers ratio /% | 22.20 | 15.50 | 4.10 | 28.60 | 30.00 | 11.30 | 8.09 | 19.53 |
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Table 4. Information of image pairs
| OP | PRO | PN | SCR | SC | NAP | MAP | MLE | TDD | OP+ | PRO+ | PN+ | SCR+ | SC+ | NAP+ | MAP+ | MLE+ | TDD+ |
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Wall | 0.43 | 0.54 | 0.68 | 0.78 | 0.71 | 0.96 | 0.91 | 0.82 | 0.64 | 0.22 | 0.29 | 0.71 | 0.54 | 0.65 | 0.69 | 0.62 | 0.54 | 0.55 | Graf1 | 1.20 | 0.66 | 0.87 | 1.44 | 0.94 | 1.84 | 1.47 | 1.66 | 0.84 | 0.52 | 0.43 | 0.81 | 0.81 | 0.84 | 0.88 | 0.65 | 0.80 | 0.73 | Graf2 | 3.60 | 0.85 | 0.57 | 0.97 | 0.60 | 1.49 | 1.34 | 1.15 | 0.79 | 1.41 | 0.63 | 0.72 | 0.72 | 0.68 | 0.76 | 0.74 | 0.68 | 0.72 | Book | 1.14 | 0.51 | 1.01 | 1.03 | 1.04 | 1.68 | 1.02 | 1.24 | 0.58 | 0.86 | 0.35 | 0.55 | 0.56 | 0.70 | 0.74 | 0.35 | 0.28 | 0.50 | Boat1 | 0.74 | 0.56 | 1.02 | 1.83 | 1.21 | 2.43 | 1.87 | 1.91 | 0.81 | 0.71 | 0.48 | 0.66 | 0.92 | 0.82 | 0.98 | 0.61 | 0.75 | 0.79 | Boat2 | 3.39 | 0.23 | 1.14 | 1.50 | 1.34 | 2.30 | 1.80 | 2.10 | 0.69 | 0.85 | 0.25 | 0.72 | 0.77 | 0.81 | 0.75 | 0.85 | 0.74 | 0.51 | Valbonne | 2.08 | 0.54 | 0.87 | 1.15 | 0.50 | 1.60 | 1.35 | 1.30 | 0.60 | 1.02 | 0.32 | 0.65 | 0.54 | 0.49 | 0.80 | 0.73 | 0.64 | 0.31 | Bonhall | 3.49 | 0.41 | 1.32 | 1.33 | 1.05 | 1.05 | 1.37 | 1.04 | 0.87 | 1.03 | 0.77 | 0.73 | 0.69 | 0.74 | 0.70 | 0.70 | 0.70 | 0.60 |
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Table 5. Comparison of runtime
| OP | PRO | PN | SCR | SC | NAP | MAP | MLE | TDD | OP+ | PRO+ | PN+ | SCR+ | SC+ | NAP+ | MAP+ | MLE+ | TDD+ |
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Wall | 210 | 190 | 221 | 225 | 223 | 174 | 160 | 150 | 34 | 220 | 229 | 223 | 227 | 225 | 224 | 230 | 233 | 226 | Graf1 | 365 | 255 | 340 | 330 | 346 | 143 | 147 | 128 | 6 | 370 | 339 | 350 | 341 | 344 | 281 | 340 | 335 | 320 | Graf2 | 81 | 22 | 51 | 36 | 53 | 20 | 19 | 19 | 6 | 99 | 65 | 79 | 67 | 82 | 51 | 65 | 69 | 36 | Book | 374 | 433 | 433 | 434 | 434 | 368 | 387 | 397 | 179 | 354 | 432 | 433 | 433 | 433 | 428 | 433 | 433 | 433 | Boat1 | 891 | 958 | 959 | 957 | 958 | 558 | 933 | 937 | 364 | 945 | 958 | 958 | 956 | 958 | 887 | 958 | 957 | 958 | Boat2 | 296 | 353 | 354 | 353 | 355 | 97 | 64 | 60 | 5 | 343 | 353 | 354 | 353 | 354 | 249 | 347 | 347 | 294 | Valbonne | 132 | 92 | 141 | 112 | 141 | 51 | 51 | 42 | 15 | 145 | 125 | 156 | 127 | 155 | 111 | 127 | 130 | 65 | Bonhall | 300 | 304 | 291 | 317 | 277 | 196 | 233 | 233 | 65 | 336 | 327 | 300 | 321 | 295 | 307 | 327 | 326 | 310 |
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Table 6. Comparison of number of obtained inliers