The principles and practice of holographic recording of plankton

Hobson, P. R.; Watson, John

doi:10.1088/1464-4258/4/4/362

Cited by 53 publications

(25 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using the forward movement of the AUV, a stripe of light can provide the map of a seabed (Jaffe, 1988). Underwater holography is used in marine biology in order to study the plankton, because it allows small-scale 3D reconstruction with high accuracy (Hobson, 2002).…”

Section: Underwater 3d Techniquesmentioning

confidence: 99%

A Comparison Between Active and Passive Techniques for Underwater 3d Applications

Bianco

Gallo

Bruno

et al. 2012

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

View full text Add to dashboard Cite

ABSTRACT:In the field of 3D scanning, there is an increasing need for more accurate technologies to acquire 3D models of close range objects. Underwater exploration, for example, is very hard to perform due to the hostile conditions and the bad visibility of the environment. Some application fields, like underwater archaeology, require to recover tridimensional data of objects that cannot be moved from their site or touched in order to avoid possible damages. Photogrammetry is widely used for underwater 3D acquisition, because it requires just one or two digital still or video cameras to acquire a sequence of images taken from different viewpoints. Stereo systems composed by a pair of cameras are often employed on underwater robots (i.e. ROVs, Remotely Operated Vehicles) and used by scuba divers, in order to survey archaeological sites, reconstruct complex 3D structures in aquatic environment, estimate in situ the length of marine organisms, etc. The stereo 3D reconstruction is based on the triangulation of corresponding points on the two views. This requires to find in both images common points and to match them (correspondence problem), determining a plane that contains the 3D point on the object. Another 3D technique, frequently used in air acquisition, solves this point-matching problem by projecting structured lighting patterns to codify the acquired scene. The corresponding points are identified associating a binary code in both images. In this work we have tested and compared two whole-field 3D imaging techniques (active and passive) based on stereo vision, in underwater environment. A 3D system has been designed, composed by a digital projector and two still cameras mounted in waterproof housing, so that it can perform the various acquisitions without changing the configuration of optical devices. The tests were conducted in a water tank in different turbidity conditions, on objects with different surface properties. In order to simulate a typical seafloor, we used various concentrations of clay. The performances of the two techniques are described and discussed. In particular, the point clouds obtained are compared in terms of number of acquired 3D points and geometrical deviation.

show abstract

Section: Underwater 3d Techniquesmentioning

confidence: 99%

A Comparison Between Active and Passive Techniques for Underwater 3d Applications

Bianco

Gallo

Bruno

et al. 2012

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

View full text Add to dashboard Cite

show abstract

“…Ferraro et al 30 have recently proposed an autofocus algorithm for digital inline holography that tracks the axial displacement of the sample in real time by measuring the phase shift of the hologram fringes. The use of an autofocus method has also been reported by Hobson and Watson, 31 although they do not give details of its implementation.…”

Section: B Related Workmentioning

confidence: 99%

Autofocus for digital Fresnel holograms by use of a Fresnelet-sparsity criterion

2004

View full text Add to dashboard Cite

We propose a robust autofocus method for reconstructing digital Fresnel holograms. The numerical reconstruction involves simulating the propagation of a complex wave front to the appropriate distance. Since the latter value is difficult to determine manually, it is desirable to rely on an automatic procedure for finding the optimal distance to achieve high-quality reconstructions. Our algorithm maximizes a sharpness metric related to the sparsity of the signal's expansion in distance-dependent waveletlike Fresnelet bases. We show results from simulations and experimental situations that confirm its applicability.

show abstract

“…For n > 1; the IOPL represents an optically foreshortened distance [136], [161], [113]. This is especially important for oceanic holography, where the waves pass through water with an index of refraction n = 1:33 1:35 [291], [256] and at least one optical window with n ranging from 1:4 1:8 [155].…”

Section: Introduction To Digital Holographymentioning

confidence: 99%

Computational imaging and automated identification for aqueous environments

Loomis¹

2011

View full text Add to dashboard Cite

Sampling the vast volumes of the ocean requires tools capable of observing from a distance while retaining detail necessary for biology and ecology, ideal for optical methods. Algorithms that work with existing SeaBED AUV imagery are developed, including habitat classi…cation with bag-of-words models and multi-stage boosting for rock…sh detection. Methods for extracting images of …sh from videos of longline operations are demonstrated.A prototype digital holographic imaging device is designed and tested for quantitative in situ microscale imaging. Theory to support the device is developed, including particle noise and the e¤ects of motion. A Wigner-domain model provides optimal settings and optical limits for spherical and planar holographic references.Algorithms to extract the information from real-world digital holograms are created. Focus metrics are discussed, including a novel focus detector using local Zernike moments. Two methods for estimating lateral positions of objects in holograms without reconstruction are presented by extending a summation kernel to spherical references and using a local frequency signature from a Riesz transform. A new metric for quickly estimating object depths without reconstruction is proposed and tested. An example application, quantifying oil droplet size distributions in an underwater plume, demonstrates the e¢ cacy of the prototype and algorithms. Course work at MIT and WHOI was helpful throughout this thesis. In particular, course materials and projects from Dr. Antonio Torralba (computer vision, detection, and boosting), Dr. Frédo Durand (computational imaging, segmentation, and probability), Dr. Rosalind Picard (machine learning, pattern recognition, and probability), Dr. Alan 4 Edelman (parallel computing and algorithms), and Dr. Barbastathis (optical systems) are re ‡ected directly, in several cases extended after the course to become complete sections of this thesis.The MIT Museum has provided unique outreach opportunities for the ideas presented in this thesis. Seth Riskin originally involved our lab in holography activities at the MIT Museum, then Kurt Hasselbalch later proposed and guided the development of an interactive display on plankton holography. The computational approaches I learned for the museum display led to further scienti…c development and spurred the use of GPUs for processing; Section 3.3.5 is a direct consequence, as is the majority of the data processing performed throughout this thesis.In reference to data processing, Matlab/MEX and NVIDIA's CUDA have been daily cornerstones for which I am continually thankful. Finally, mad props go to Dr. José "Pepe" Domínguez-Caballero, the most in ‡uential 5 person in my scienti…c development while at MIT. Pepe taught me digital holography and worked one-on-one with me throughout the beginning of my grad student career. He continued to be involved as a fellow holographer, a mentor, and a friend, discussing ideas, encouraging active experimentation, maintaining a curiosity about optics, and o¤ering eno...

show abstract

The principles and practice of holographic recording of plankton

Cited by 53 publications

References 50 publications

A Comparison Between Active and Passive Techniques for Underwater 3d Applications

A Comparison Between Active and Passive Techniques for Underwater 3d Applications

Autofocus for digital Fresnel holograms by use of a Fresnelet-sparsity criterion

Computational imaging and automated identification for aqueous environments

Contact Info

Product

Resources

About