Atomic Spectra Database

This review paper discusses the role of haptics within virtual medical training applications, particularly, where it can be used to aid a practitioner to learn and practice a task. The review summarizes aspects to be considered in the deployment of haptics technologies in medical training. First, both force/torque and tactile feedback hardware solutions that are currently produced commercially and in academia are reviewed, followed by the available haptics-related software and then an in-depth analysis of medical training simulations that include haptic feedback. The review is summarized with scrutiny of emerging technologies and discusses future directions in the field.

The Role of Haptics in Medical Training Simulators: A Survey of the State of the Art

Embodiments include a system for determining cardiovascular information for a patient. The system may include at least one computer system configured to receive patient-specific data regarding a geometry of the patient's heart, and create a three-dimensional model representing at least a portion of the patient's heart based on the patient-specific data. The at least one computer system may be further configured to create a physics-based model relating to a blood flow characteristic of the patient's heart and determine a fractional flow reserve within the patient's heart based on the three-dimensional model and the physics-based model.

Method and system for patient-specific modeling of blood flow

Schlieren and shadowgraph techniques are used around the world for imaging and measuring phenomena in transparent media. These optical methods originated long ago in parallel with telescopes and microscopes, and although it might seem that little new could be expected of them on the timescale of 15 years, in fact several important things have happened that are reviewed here. The digital revolution has had a transformative effect, replacing clumsy photographic film methods with excellent—though expensive—high-speed video cameras, making digital correlation and processing of shadow and schlieren images routine, and providing an entirely-new synthetic schlieren technique that has attracted a lot of attention: background-oriented schlieren or BOS. Several aspects of modern schlieren and shadowgraphy depend upon laptop-scale computer processing of images using an imagecapable language such as MATLABTM. BOS, shock-wave tracking, schlieren velocimetry, synthetic streak-schlieren, and straightforward quantitative density measurements in 2D flows are all recent developments empowered by this digital and computational capability.

https://iopscience.iop.org/article/10.1088/1361-6501/aa5748/pdf

A review of recent developments in schlieren and shadowgraph techniques

The interaction of light and matter in the world surrounding us is of striking complexity and beauty. Since the very beginning of computer graphics, adequate modelling of these processes and efficient computation is an intensively studied research topic and still not a solved problem. The inherent complexity stems from the underlying physical processes as well as the global nature of the interactions that let light travel within a scene. This paper reviews the state of the art in interactive global illumination (GI) computation, i.e., methods that generate an image of a virtual scene in less than 1 s with an as exact as possible, or plausible, solution to the light transport. Additionally, the theoretical background and attempts to classify the broad field of methods are described. The strengths and weaknesses of different approaches, when applied to the different visual phenomena, arising from light interaction are compared and discussed. Finally, the paper concludes by highlighting design patterns for interactive GI and a list of open problems. © 2012 Wiley Periodicals, Inc.

https://cg.ivd.kit.edu/publications/2012/GISTAR/GISTAR.pdf

The State of the Art in Interactive Global Illumination

Volumetric rendering is widely used to examine 3D scalar fields from CT/MRI scanners and numerical simulation datasets. One key aspect of volumetric rendering is the ability to provide perceptual cues to aid in understanding structure contained in the data. While shading models that reproduce natural lighting conditions have been shown to better convey depth information and spatial relationships, they traditionally require considerable (pre) computation. In this paper, a shading model for interactive direct volume rendering is proposed that provides perceptual cues similar to those of ambient occlusion, for both solid and transparent surface-like features. An image space occlusion factor is derived from the radiative transport equation based on a specialized phase function. The method does not rely on any precomputation and thus allows for interactive explorations of volumetric data sets via on-the-fly editing of the shading model parameters or (multi-dimensional) transfer functions while modifications to the volume via clipping planes are incorporated into the resulting occlusion-based shading.

/pdf/a-directional-occlusion-shading-model-for-interactive-direct-4qwqln4qnf.pdf

A directional occlusion shading model for interactive direct volume rendering

Methods and apparatus provide realistic training in endovascular and endoluminal procedures. One embodiment includes modeling accurately the tubular anatomy of a patient to enable optimized simulation. One embodiment includes simulating the interaction between a flexible device and the anatomy and optimizing the computation. One embodiment includes replicating the functionality of therapeutic devices, e.g. stents, and simulating their interaction with anatomy. One embodiment includes computing hemodynamics inside the vascular model. One embodiment includes reproducing visual feedback, using synthetic X-ray imaging and/or or visible light rendering. One embodiment includes generating contrast agent injection and propagation through a tubular network. One embodiment includes reproducing aspects of the physical environment of an operating room by simulating or tracking, such as C-arm control panel, foot pedals, monitors, real catheters and guidewires, etc. One embodiment includes tracking instrument position and mimicking haptic feedback experienced when manipulating certain medical devices.

Methods and apparatus for simulation of endovascular and endoluminal procedures

Despite their numerous applications, efficiently rendering participating media remains a challenging task due to the intricacy of the radiative transport equation. As they provide a generic means of solving a wide variety of problems, numerical methods are most often used to solve the air-light integral even under simplifying assumptions. In this paper, we present a novel analytical approach to single scattering from isotropic point light sources in homogeneous media. We derive the first closed-form solution to the air-light integral in isotropic media and extend this formulation to anisotropic phase functions. The technique relies neither on pre-computation nor on storage, and we provide a practical implementation allowing for an explicit control on the accuracy of the solutions. Finally, we demonstrate its quantitative and qualitative benefits over both previous numerical and analytical approaches.

An Analytical Solution to Single Scattering in Homogeneous Participating Media

Accurately rendering fires is a challenging problem due to the various subtle ways in which the electromagnetic waves interact with this complex participating medium. We present a new method for physically-based rendering of flames from detailed simulations of flame dynamics which accounts for their unique characteristics. Instead of relying on ad-hoc models, we build on fundamental molecular physics to compute the spectrally dependent absorption, emission and scattering properties of the various chemical compounds found in the fire. Combined with a model of the refractive process, and with tone-mapping techniques simulating the visual adaptation of a human observer, we are able to generate highly realistic renderings of various types of flames, including colorful flames containing chemical species with very characteristic spectral properties.

Physically-based realistic fire rendering

Due to the intricate nature of the equation governing light transport in participating media, accurately and efficiently simulating radiative energy transfer remains very challenging in spite of its broad range of applications. As an alternative to traditional numerical estimation methods such as ray-marching and volume-slicing, a few analytical approaches to solving single scattering have been proposed but current techniques are limited to the assumption of isotropy, rely on simplifying approximations and/or require substantial numerical precomputation and storage. In this paper, we present the very first closed-form solution to the air-light integral in homogeneous media for general 1-D anisotropic phase functions and punctual light sources. By addressing an open problem in the overall light transport literature, this novel theoretical result enables the analytical computation of exact solutions to complex scattering phenomena while achieving semi-interactive performance on graphics hardware for several common scattering modes.

Vincent Pegoraro

Papers

A directional occlusion shading model for interactive direct volume rendering

Methods and apparatus for simulation of endovascular and endoluminal procedures

An Analytical Solution to Single Scattering in Homogeneous Participating Media

Physically-based realistic fire rendering

A closed-form solution to single scattering for general phase functions and light distributions