Oil-immersion microscope objective lenses have been designed and optimized for the study of thin, two-dimensional object sections that are mounted immediately below the coverslip in a medium that is index matched to the immersion oil. It has been demonstrated both experimentally and through geometrical- and physical-optics theory that, when the microscope is not used with the correct coverslip or immersion oil, when the detector is not located at the optimal plane in image space, or when the object does not satisfy specific conditions, aberration will degrade both the contrast and the resolution of the image. In biology the most severe aberration is introduced when an oil-immersion objective lens is used to study thick specimens, such as living cells and tissues, whose refractive indices are significantly different from that of the immersion oil. We present a model of the three-dimensional imaging properties of a fluorescence light microscope subject to such aberration and compare the imaging properties predicted by the model with those measured experimentally. The model can be used to understand and compensate for aberration introduced to a microscope system under nondesign optical conditions so that both confocal laser scanning microscopy and optical serial sectioning microscopy can be optimized.
Existing formulations of the three-dimensional (3-D) diffraction pattern of spherical waves that is produced by a circular aperture are reviewed in the context of 3-D serial-sectioning microscopy. A new formulation for off-axis focal points is introduced that has the desirable properties of increased accuracy for larger field angles, invariance to shifts of the focal point about spheres of constant radius when the detection point is on the sphere for both intensity and amplitude fields, and invariance to shifts in three transformed coordinates for intensity fields. Finally, calculated intensity fields for both on-axis and off-axis focal points are included to illustrate the proposal that the classical 3-D diffraction patterns that have been used as analytical models in 3-D serial-sectioning fluorescence microscopy may not be accurate enough for this application.
This paper describes a method for creating object surfaces from binary-segmented data that are free from aliasing and terracing artifacts. In this method, a net of linked surface nodes is created over the surface of the binary object. The positions of the nodes are adjusted iteratively to reduce energy in the surface net while satisfying the constraint that each element in the surface net must remain within its original surface cube. This constraint ensures that fine detail such as cracks and thin protrusions that are present in the binary data are maintained.This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Abstract. This paper describes a method for creating object surfaces from binary-segmented data that are free from aliasing and terracing artifacts. In this method, a net of linked surface nodes is created over the surface of the binary object. The positions of the nodes are adjusted iteratively to reduce energy in the surface net while satisfying the constraint that each element in the surface net must remain within its original surface cube. This constraint ensures that ne detail such a s c r a c ks and thin protrusions that are present in the binary data are maintained.
Figure 1: Shaded volm redredspheres stored~"th two valuesper voml: a val~indicating t~distme to the closest su~acepoint; and a bti~intensi~vk The sphere in a) has radiu 30 voxk and is stored in an array of size 643. The spheres in b), c), and d) he radii 3 vouk, 2 vomk & 1.5 vo~k respectively and are stored in arrays of size 103. The sutiace noml used in su~ace shading was calculated using a 6-point central di~mence operator on the &tance values. RemrMly moth shading can be achieved for these low resolution data VOIW because zb~ction of the &me-to-closest time vm"es mothly across su~aces. (See color phte.)Abstract gh qufity rendering and physics-basal modekg in volume graphics havekn Emited because intensity-basal volumetric data do not represent surfaces we~M@ spatial frequencies due to abropt intensity chang= at object surfaces rtit in jaggd or terraced surfams in renderd images. me use of a distance-@closestsurface function to encode object surfaces is proposal~s function TTariessmootiy across surfaces and hence can be amtely ranstructi from sampled * me zer-tiue is~surface of the distance map yields the object surface and the derivative of the distance map yields the surface noti &arnples of rendered images are presenti along with anew method for cdtiating distance maps from sarnpld binary daK eywork \TolurneRendering, lblnme Graphics, Surgid Sinm-Iation, hfdcd Applications
Figure 1: Shaded, volume rendered spheres stored with two values per voxel: a value indicating the distance to the closest surface point; and a binary intensity value. The sphere in a) has radius 30 voxels and is stored in an array of size 64 3 . The spheres in b), c), and d) have radii 3 voxels, 2 voxels and 1.5 voxels respectively and are stored in arrays of size 10 3 . The surface normal used in surface shading was calculated using a 6-point central difference operator on the distance values. Remarkably smooth shading can be achieved for these low resolution data volumes because the function of the distance-to-closest surface varies smoothly across surfaces. AbstractHigh quality rendering and physics-based modeling in volume graphics have been limited because intensity-based volumetric data do not represent surfaces well. High spatial frequencies due to abrupt intensity changes at object surfaces result in jagged or terraced surfaces in rendered images. The use of a distance-to-closestsurface function to encode object surfaces is proposed. This function varies smoothly across surfaces and hence can be accurately reconstructed from sampled data. The zero-value iso-surface of the distance map yields the object surface and the derivative of the distance map yields the surface normal. Examples of rendered images are presented along with a new method for calculating distance maps from sampled binary data.
Surgical simulation has many applications in medical education, surgical training, surgical planning, and intra-operative assistance. However, extending current surface-based computer graphics methods to model phenomena such as the deformation, cutting, tearing, or repairing of soft tissues poses significant challenges for real-time interactions. This paper discusses the use of volumetric methods for modeling complex anatomy and tissue interactions. New techniques are introduced that use volumetric methods for modeling soft tissue deformation and tissue cutting at interactive rates. An initial prototype for simulating arthroscopic knee surgery is described which uses volumetric models of the knee derived from 3D Magnetic Resonance Imaging, visual feedback via real-time volume and polygon rendering, and haptic feedback provided by a force feedback device. To be published in Journal of Medical Image Analysis, December, 1997.This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy i n whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories of Cambridge, Massachusetts; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories. All rights reserved. Copyright © Mitsubishi Electric Information AbstractSurgical simulation has many applications in medical education, surgical training, surgical planning, and intra-operative assistance. However, extending current surfacebased computer graphics methods to model phenomena such as the deformation, cutting, tearing, or repairing of soft tissues poses significant challenges for real-time interactions. This paper discusses the use of volumetric methods for modeling complex anatomy and tissue interactions. New techniques are introduced that use volumetric methods for modeling soft tissue deformation and tissue cutting at interactive rates. An initial prototype for simulating arthroscopic knee surgery is described which uses volumetric models of the knee derived from 3D Magnetic Resonance Imaging, visual feedback via real-time volume and polygon rendering, and haptic feedback provided by a force feedback device.
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