| 1. |
- Barnes, N., et al.
(författare)
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Real-time regular polygonal sign detection
- 2006
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a new adaptation of the regular polygon detection algorithm for real-time road sign detection for autonomous vehicles. The method is robust to partial occlusion and fading, and insensitive to lighting conditions. We experimentally demonstrate its application to the detection of various signs, particularly evaluating it on a sequence of roundabout signs taken from the ANU/NICTA vehicle. The algorithm runs faster than 20 frames per second on a standard PC, detecting signs of the size that appears in road scenes, as observed from a camera mounted on the rear-vision mirror. The algorithm uses the symmetric nature of regular polygonal shapes, we also use the constrained appearance of such shapes in the road scene to the car in order to facilitate their fast, robust detection.
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| 2. |
- Barnes, N., et al.
(författare)
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Regular polygon detection
- 2005
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Ingår i: Proceedings - 10th IEEE International Conference on Computer Vision. - : IEEE Computer Society. - 076952334X - 9780769523347 ; , s. 778-785
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Konferensbidrag (refereegranskat)abstract
- This paper describes a new robust regular polygon detector. The regular polygon transform is posed as a mixture of regular polygons in a five dimensional space. Given the edge structure of an image, we derive the a posteriori probability for a mixture of regular polygons, and thus the probability density function for the appearance of a mixture of regular polygons. Likely regular polygons can be isolated quickly by discretising and collapsing the search space into three dimensions. The remaining dimensions may be efficiently recovered subsequently using maximum likelihood at the locations of the most likely polygons in the subspace. This leads to an efficient algorithm. Also the a posteriori formulation facilitates inclusion of additional a priori information leading to real-time application to road sign detection. The use of gradient information also reduces noise compared to existing approaches such as the generalised Hough transform. Results are presented for images with noise to show stability. The detector is also applied to two separate applications: real-time road sign detection for on-line driver assistance; and feature detection, recovering stable features in rectilinear environments.
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| 3. |
- Barnes, Nick, et al.
(författare)
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The regular polygon detector
- 2010
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Ingår i: Pattern Recognition. - : Elsevier BV. - 0031-3203 .- 1873-5142. ; 43:3, s. 592-602
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a robust regular polygon detector. Given image edges, we derive the a posteriori probability for a mixture of regular polygons, and thus the probability density function for the appearance of a set of regular polygons. Likely regular polygons can be isolated quickly by discretising and collapsing the search space into three dimensions. We derive a complete formulation for efficiently recovering the remaining dimensions using maximum likelihood at the locations of the most likely polygons. Results show robustness to noise, the ability to find and differentiate different shape types, and to perform real-time sign detection for driver assistance.
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| 4. |
- Cornelius, Hugo, et al.
(författare)
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Detecting bilateral symmetry in perspective
- 2006
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Ingår i: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition. - 0769526462 - 9780769526461
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Konferensbidrag (refereegranskat)abstract
- A method is presented for efficiently detecting bilateral symmetry on planar surfaces under perspective projection. The method is able to detect local or global symmetries, locate symmetric surfaces in complex backgrounds, and detect multiple incidences of symmetry. Symmetry is simultaneously evaluated across all locations, scales, orientations and under perspective skew. Feature descriptors robust to local affine distortion are used to match pairs of symmetric features. Feature quadruplets are then formed from these symmetric feature pairs. Each quadruplet hypothesises a locally planar 3D symmetry that can be extracted under perspective distortion. The method is posed independently of a specific feature detector or descriptor. Results are presented demonstrating the efficacy of the method for detecting bilateral symmetry under perspective distortion. Our unoptimised Matlab implementation, running on a standard PC, requires of the order of 20 seconds to process images with 1,000 feature points.
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| 5. |
- Cornelius, Hugo, et al.
(författare)
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Detecting rotational symmetry under affine projection
- 2006
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Ingår i: 18th International Conference on Pattern Recognition, Vol 2, Proceedings. - LOS ALAMITOS, CA : IEEE COMPUTER SOC. - 0769525210 ; , s. 292-295
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Konferensbidrag (refereegranskat)abstract
- A new method is presented for detecting planar rotational symmetry under affine projection. The method can deal with partial occlusion and is able to detect multiple rotationally symmetric surfaces in complex backgrounds. The order of rotational symmetry can be estimated, and if it is greater than two, the tilt and orientation of the rotationally symmetric surface can be found and the symmetric region segmented. Local features robust to local affine distortion are matched to obtain pairs of features. Each feature pair hypothesises a set of centres of rotation for different tilts and orientations and the centres of rotation that are close to each other are grouped together to find the dominant rotational symmetries in the image. The method is posed independently of a specific feature detector and descriptor Results are presented on natural images.
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| 6. |
- Cornelius, Hugo, et al.
(författare)
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Efficient symmetry detection using local affine frames
- 2007
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Ingår i: Image Analysis, Proceedings. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783540730392 ; , s. 152-161
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Konferensbidrag (refereegranskat)abstract
- We present an efficient method for detecting planar bilateral symmetries under perspective projection. The method uses local affine frames (LAFs) constructed on maximally stable extremal regions or any other affine covariant regions detected in the image to dramatically improve the process of detecting symmetric objects under perspective distortion. In contrast to the previous work no Hough transform, is used. Instead, each symmetric pair of LAFs votes just once for a single axis of symmetry. The time complexity of the method is n log(n), where n is the number of LAFs, allowing a near real-time performance. The proposed method is robust to background clutter and partial occlusion and is capable of detecting an arbitrary number of symmetries in the image.
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| 7. |
- Fletcher, L., et al.
(författare)
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Correlating driver gaze with the road scene for driver assistance systems
- 2005
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Ingår i: Robotics and Autonomous Systems. - : Elsevier BV. - 0921-8890 .- 1872-793X. ; 52:1, s. 71-84
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Tidskriftsartikel (refereegranskat)abstract
- A driver assistance system (DAS) should support the driver by monitoring road and vehicle events and presenting relevant and timely information to the driver. It is impossible to know what a driver is thinking, but we can monitor the driver's gaze direction and compare it with the position of information in the driver's viewfield to make inferences. In this way, not only do we monitor the driver's actions, we monitor the driver's observations as well. In this paper we present the automated detection and recognition of road signs, combined with the monitoring of the driver's response. We present a complete system that reads speed signs in real-time, compares the driver's gaze, and provides immediate feedback if it appears the sign has been missed by the driver.
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| 8. |
- Loy, Gareth, et al.
(författare)
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Detecting symmetry and symmetric constellations of features
- 2006
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Ingår i: COMPUTER VISION - ECCV 2006, PT 2, PROCEEDINGS. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 3540338349 ; , s. 508-521
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Konferensbidrag (refereegranskat)abstract
- A novel and efficient method is presented for grouping feature points on the basis of their underlying symmetry and characterising the symmetries present in an image. We show how symmetric pairs of features can be efficiently detected, how the symmetry bonding each pair is extracted and evaluated, and how these can be grouped into symmetric constellations that specify the dominant symmetries present in the image. Symmetries over all orientations and radii are considered simultaneously, and the method is able to detect local or global symmetries, locate symmetric figures in complex backgrounds, detect bilateral or rotational symmetry, and detect multiple incidences of symmetry.
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| 9. |
- Loy, Gareth, et al.
(författare)
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Fast shape-based road sign detection for a driver assistance system
- 2004
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Ingår i: 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). - 0780384636 ; , s. 70-75
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Konferensbidrag (refereegranskat)abstract
- A new method is presented for detecting triangular, square and octagonal road signs efficiently and robustly. The method uses the symmetric nature of these shapes, together with the pattern of edge orientations exhibited by equiangular polygons with a known number of sides, to establish possible shape centroid locations in the image. This approach is invariant to in-plane rotation and returns the location and size of the shape detected. Results on still images show a detection rate of over 95%. The method is efficient enough for real-time applications, such as on-board-vehicle sign detection.
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| 10. |
- Loy, Gareth, et al.
(författare)
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Monocular 3D reconstruction of human motion in long action sequences
- 2004
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Ingår i: COMPUTER VISION. - BERLIN : SPRINGER. - 3540219811 ; , s. 442-455
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Konferensbidrag (refereegranskat)abstract
- A novel algorithm is presented for the 3D reconstruction of human action in long (> 30 second) monocular image sequences. A sequence is represented by a small set of automatically found representative keyframes. The skeletal joint positions are manually located in each keyframe and mapped to all other frames in the sequence. For each keyframe a 3D key pose is created, and interpolation between these 3D body poses, together with the incorporation of limb length and symmetry constraints, provides a smooth initial approximation of the 3D motion. This is then fitted to the image data to generate a realistic 3D reconstruction. The degree of manual input required is controlled by the diversity of the sequence's content. Sports' footage is ideally suited to this approach as it frequently contains a limited number of repeated actions. Our method is demonstrated on a long (36 second) sequence of a woman playing tennis filmed with a non-stationary camera. This sequence required manual initialisation on < 1.5% of the frames, and demonstrates that the system can deal with very rapid motion, severe self-occlusions, motion blur and clutter occurring over several concurrent frames. The monocular 3D reconstruction is verified by synthesising a view from the perspective of a 'ground truth' reference camera, and the result is seen to provide a qualitatively accurate 3D reconstruction of the motion.
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