Calibration of Central Catadioptric Cameras Using a DLT-Like Approach

Puig, Luis; Baştanlar, Yalın; Sturm, Peter; Guerrero, J. J.; Barreto, João Pedro

doi:10.1007/s11263-010-0411-1

Cited by 61 publications

(34 citation statements)

References 31 publications

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“…For the omnidirectional camera, we use the sphere camera model [19] which is able to cover both catadioptric (mirrored) omnidirectional cameras and fisheye cameras. There are a few calibration methods proposed for the calibration using the sphere model [20,21], we preferred to employ [20] since a MATLAB toolbox is provided.…”

Section: Intrinsic Calibrationmentioning

confidence: 99%

A simplified two-view geometry based external calibration method for omnidirectional and PTZ camera pairs

Baştanlar

2016

Pattern Recognition Letters

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a b s t r a c tThe external calibration of a camera system is essential for most of the applications that involve an omnidirectional and a pan-tilt-zoom (PTZ) camera. The methods in the literature fall into two major categories; (1) a complete external calibration of the system which allows all degrees of freedom but highly time consuming, (2) spatial mapping between the pixel coordinates in omnidirectional camera and pan/tilt angles of the PTZ camera instead of explicitly computing the rotation and translation. Most methods in this category make restrictive assumptions about the camera setup such as optical axes of the cameras coincide. We propose an external calibration method that is effective and practical. Using the two-view geometry principles and making reasonable assumptions about the camera setup, calibration is performed with just two scene points. We extract rotation using the point correspondences in images. Locating the PTZ camera in the omnidirectional image is used to find the translation parameters and the real distance between the two scene points lets us compute the translation in correct scale. Results of the simulated and real image experiments show that our method works effectively in real world cases and its accuracy is comparable to the state-of-the-art methods.

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Section: Intrinsic Calibrationmentioning

confidence: 99%

A simplified two-view geometry based external calibration method for omnidirectional and PTZ camera pairs

Baştanlar

2016

Pattern Recognition Letters

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“…There are several methods to perform sphere camera model calibration [19,21]. We used [19] since a MATLAB toolbox is provided with it.…”

Section: Sphere Camera Modelmentioning

confidence: 99%

A direct approach for object detection with catadioptric omnidirectional cameras

Cinaroglu

Baştanlar

2015

SIViP

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In this paper, we present an omnidirectional vision-based method for object detection. We first adopt the conventional camera approach that uses sliding windows and histogram of oriented gradients (HOG) features. Then, we describe how the feature extraction step of the conventional approach should be modified for a theoretically correct and effective use in omnidirectional cameras. Main steps are modification of gradient magnitudes using Riemannian metric and conversion of gradient orientations to form an omnidirectional sliding window. In this way, we perform object detection directly on the omnidirectional images without converting them to panoramic or perspective images. Our experiments, with synthetic and real images, compare the proposed approach with regular (unmodified) HOG computation on both omnidirectional and panoramic images. Results show that the proposed approach should be preferred. Keywords Catadioptric omnidirectional cameras · Object detection · Human detection · Car detection · Vehicle detectionElectronic supplementary material The online version of this article

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“…Then this point is projected from the unitary sphere to the image plane through a variable projection point, which is determined by the geometry of the mirror (parameter ξ). If the system is calibrated [18], it is also possible like in any conventional camera, to map the catadioptric image to the unitary sphere.…”

Section: Computing a Generic Metric On The Spherementioning

confidence: 99%

Scale space for central catadioptric systems: Towards a generic camera feature extractor

Puig

Guerrero

2011

2011 International Conference on Computer Vision

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In this paper we propose a new approach to compute the scale space of any omnidirectional image acquired with a central catadioptric system. When these cameras are central they are explained using the sphere camera model, which unifies in a single model, conventional, paracatadioptric and hypercatadioptric systems. Scale space is essential in the detection and matching of interest points, in particular scale invariant points based on Laplacian of Gaussians, like the well known SIFT. We combine the sphere camera model and the partial differential equations framework on manifolds, to compute the Laplace-Beltrami (LB) operator which is a second order differential operator required to perform the Gaussian smoothing on catadioptric images. We perform experiments with synthetic and real images to validate the generalization of our approach to any central catadioptric system.

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Calibration of Central Catadioptric Cameras Using a DLT-Like Approach

Cited by 61 publications

References 31 publications

A simplified two-view geometry based external calibration method for omnidirectional and PTZ camera pairs

A simplified two-view geometry based external calibration method for omnidirectional and PTZ camera pairs

A direct approach for object detection with catadioptric omnidirectional cameras

Scale space for central catadioptric systems: Towards a generic camera feature extractor

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