Optical Systems

Kingslake, R.

doi:10.1016/b978-0-12-408660-9.50004-0

Cited by 49 publications

(48 citation statements)

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“…Photometric calibration deals with the decrease of light intensity falling on the image plane with an increasing distance to the image center (Kingslake, 1983). Asada et al (1996) propose an approach to estimate the intensity reduction due to vignetting.…”

Section: State Of the Artmentioning

confidence: 99%

Towards the Influence of a Car Windshield on Depth Calculation With a Stereo Camera System

Hanel¹,

Hoegner²,

Stilla³

2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Stereo camera systems in cars are often used to estimate the distance of other road users from the car. This information is important to improve road safety. Such camera systems are typically mounted behind the windshield of the car. In this contribution, the influence of the windshield on the estimated distance values is analyzed. An offline stereo camera calibration is performed with a moving planar calibration target. In a standard procedure bundle adjustment, the relative orientation of the cameras is estimated. The calibration is performed for the identical stereo camera system with and without a windshield in between. The base lengths are derived from the relative orientation in both cases and are compared. Distance values are calculated and analyzed. It can be shown, that the difference of the base length values in the two cases is highly significant. Resulting effects on the distance calculation up to a half meter occur.

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Section: State Of the Artmentioning

confidence: 99%

Towards the Influence of a Car Windshield on Depth Calculation With a Stereo Camera System

Hanel¹,

Hoegner²,

Stilla³

2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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“…No doubt that as the primary mirror diameter becomes lager, a number of challenges occur in telescope technology, and primary mirror supporting technology will be one of them. 1,2 Primary mirror supporting system (PMSS) bears the primary mirror weight and controls the mirror attitude toward telescope mirror cell, without causing excessive surface deformation on primary mirror. The PMSS design should follow two basic principles to guarantee telescope imaging quality: First, the output force of all supporting actuators must be theoretically equal to avoid large deformation on mirror surface, although the active supporting system will adjust the output force in detail; second, the supporting system must be able to compensate the relative position bias between the primary mirror and mirror cell, namely, the supporting system must be a position control system.…”

Section: Introductionmentioning

confidence: 99%

Novel electro-hydraulic position control system for primary mirror supporting system

Peng

Gong

Yang

et al. 2016

Advances in Mechanical Engineering

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In the field of modern large-scale telescope, primary mirror supporting system technology faces the difficulties of theoretically uniform output force request and bias compensation. Therefore, a novel position control system combining hydraulic system with servo motor system is introduced. The novel system ensures uniform output force on supporting points without complicating the mechanical structure. The structures of both primary mirror supporting system and novel position system are described. Then, the mathematical model of novel position control system is derived for controller selection. A proportional-derivative controller is adopted for simulations and experiments of step response and triangle path tracking. The results show that proportional-derivative controller guarantees the system with micrometerlevel positioning ability. A modified proportional-derivative controller is utilized to promote system behavior with faster response overshoot. The novel position control system is then applied on primary mirror supporting system. Coupling effect is observed among actuator partitions, and relocation of virtual pivot supporting point is chosen as the decoupling measurement. The position keeping ability of the primary mirror supporting system is verified by rotating the mirror cell at a considerably high rate. The experiment results show that the decoupled system performs better with smaller bias and shorter recovery time.

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“…Object side telecentricity has been known in the literature [18] but in order to achieve this effect the aperture of telecentric lenses needs to be as large as the object to be viewed. This requires large, heavy and expensive lenses.…”

Section: Introductionmentioning

confidence: 99%

Image Processing and Computer Vision

Bezdek

Keller

Krisnapuram

et al. 1999

Fuzzy Models and Algorithms for Pattern Recognition and Image Processing

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Shape from focus (SFF) which uses a sequence of space-variantly defocused frames works under the constraint that there is 'no magnification' in the stack. In the presence of sensor damage and/or occlusions, there will be missing data in the observations and SFF cannot recover structure in those regions. In many applications, the capability of fillingin missing data is of critical importance. In this paper, we investigate the effect of motion parallax in SFF and demonstrate the interesting possibility of how it can be judiciously used to jointly inpaint image and depth profiles. When there is relative motion between the 3D specimen and the camera, by virtue of the inherent pixel motion in each of the frames, it is possible to obtain a focused image and depth map of the scene despite missing regions in the observations.

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Optical Systems

Cited by 49 publications

References 0 publications

Towards the Influence of a Car Windshield on Depth Calculation With a Stereo Camera System

Towards the Influence of a Car Windshield on Depth Calculation With a Stereo Camera System

Novel electro-hydraulic position control system for primary mirror supporting system

Image Processing and Computer Vision

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