A method for 3D measurement and reconstruction for active vision

Li, Youfu; Zhang, B

doi:10.1088/0957-0233/15/11/007

Cited by 15 publications

(12 citation statements)

References 12 publications

(12 reference statements)

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“…For active structured light applications a light spot (or alternatively a line or grid) is generated by a laser and is recorded by a location‐sensitive photoelectric detector. If the geometry of projection and recording device is known, the position of the light spot can be resolved (Fisher et al, 1999; Li and Zhang, 2004). On the other hand, passive structured light is used to supply a surface with an artificial texture by means of a projected random pattern.…”

Section: Methodsmentioning

confidence: 99%

Videogrammetric monitoring of as‐built membrane roof structures

Lin

Mills²,

Gosling³

2008

The Photogrammetric Record

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A monitoring system that uses applied geomatics techniques, including videogrammetry and terrestrial laser scanning, has been developed in order to investigate the dynamic behaviour of as-built membrane roof structures. To accommodate the problems involved in measuring such roof structures, examples of which include uniform surface texture and unreachable height, the system adopts a non-contact targeting methodology to substitute for traditional control techniques. In-house software was developed for processing the acquired video imagery in order to produce a sequential surface model of the membrane. This paper firstly reports on experiments conducted to demonstrate that the monitoring system was capable of measuring representative test structures with a precision of better than ±1 mm. To prove the feasibility and transferability of the system, videogrammetric monitoring campaigns were subsequently performed at a real-world test site where two different types of membrane structure were observed. The sequential 3D surface models that were generated allowed the displacement of the membrane surfaces to be investigated over a period, during which the range of the movement reached over 20 mm. The information acquired from the system is proving to be of great value to structural engineers involved in research and development of such membrane structures.

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Section: Methodsmentioning

confidence: 99%

Videogrammetric monitoring of as‐built membrane roof structures

Lin

Mills²,

Gosling³

2008

The Photogrammetric Record

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“…These limitations produce lowresolution and incomplete measurements. 19 To improve the flexible measurements based on re-calibration, a model with an automatic calibration is proposed. This model calibrates the focal length and the camera position via laser line position to avoid external recalibration during the vision task.…”

Section: Related Workmentioning

confidence: 99%

“…11,12,19 These limitations reduce the capability of the traditional measurements of variable range. [9][10][11][12][13][14][15][16][17][18][19] The proposed method performs measurements of variable range via variable focal length without recalibration during the vision task. This flexible measurement method is carried out via Bezier networks based on the line position and the focal length.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional recovering based on variable focal length via Bezier networks

Muñoz-Rodríguez

2014

The Imaging Science Journal

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An automatic technique to perform measurements of variable range via variable focal length is presented. This technique provides measurements of variable range by means of a Bezier network based on a laser line projection. The variable range measurements are performed by adjusting the camera position and the focal length. These parameters are automatically computed during the vision task by means of the line position. Also, the initial calibration of vision parameters is carried out via image processing of the laser line. Thus, the proposed technique avoids external re-calibration, which is applied by the traditional methods of flexible measurements. This leads to an improvement of accuracy of the measurements of variable range via Bezier network. It is because the proposed method does not add errors of external re-calibration to the measurement process. This technique performs measurements of variable range via magnification of the surface depth, when it is not retrieved by the initial configuration. Thus, the system adapts the setup to the resolution of complex surface, which is being profiled. Furthermore, the adjustment does not interrupt the vision procedure because the change of vision parameters is calculated in a fraction of second. The contribution of this technique is elucidated by an evaluation based on the traditional measurements of variable range. Also, the time to achieve the surface measurements is examined.

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“…Thus, the parameters to be calibrated are the matrix R , the vector t , the focal length f , the distortion coefficient δ i , the image center ( c x , c y ) and the scaling factor η . This procedure is carried out by detecting calibrated references on a reference plane and use of a transformation matrix [ 6 – 27 ]. Then, the calibration data are passed to the vision system to perform three-dimensional visualization.…”

Section: Basic Theorymentioning

confidence: 99%

“…Online re-calibration methods have also been developed to change the vision parameters during vision task [ 25 – 27 ]. In these methods, the perspective projection is determined by matching the light pattern on a reference plane.…”

Section: Introductionmentioning

confidence: 99%

Mobile Calibration Based on Laser Metrology and Approximation Networks

Muñoz-Rodríguez

2010

Sensors

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A mobile calibration technique for three-dimensional vision is presented. In this method, vision parameters are computed automatically by approximation networks built based on the position of a camera and image processing of a laser line. The networks also perform three-dimensional visualization. In the proposed system, the setup geometry can be modified online, whereby an online re-calibration is performed based on data provided by the network and the required modifications of extrinsic and intrinsic parameters are thus determined, overcoming any calibration limitations caused by the modification procedure. The mobile calibration also avoids procedures involving references, which are used in traditional online re-calibration methods. The proposed mobile calibration thus improves the accuracy and performance of the three-dimensional vision because online data of calibrated references are not passed on to the vision system. This work represents a contribution to the field of online re-calibration, as verified by a comparison with the results based on lighting methods, which are calibrated and re-calibrated via perspective projection. Processing time is also studied.

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A method for 3D measurement and reconstruction for active vision

Cited by 15 publications

References 12 publications

Videogrammetric monitoring of as‐built membrane roof structures

Videogrammetric monitoring of as‐built membrane roof structures

Three-dimensional recovering based on variable focal length via Bezier networks

Mobile Calibration Based on Laser Metrology and Approximation Networks

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