Virtual Light Source Research Articles

Evolution of Fetal Cardiac Imaging over the Last 20 Years

The purpose of this article is to describe the evaluation of a variety of congenital heart diseases (CHDs) using three-dimensional (3D) ultrasound with different software, such as Cristal Vue, Realistic Vue, LumiFlow, and Spatiotemporal Image Correlation (STIC), with HDlive and HDlive Flow Silhouette modes. These technologies provide realistic images of the fetal heart and cardiac vessels using a fixed virtual light source that allows the operator to freely select a better light source position to enhance the cardiovascular anatomical details. In addition, Fetal Intelligent Navigation Echocardiography (FINE) technology, also known as “5D Heart” or “5D”, is a technology that enables the automatic reconstruction of the nine standard fetal echocardiographic views and can alert non-specialists to suspected CHD. Through the use of artificial intelligence, an ultrasound machine is able to perform automatic anatomical and functional measurements. In addition, hese technologies enable the reconstruction of fetal cardiac structures in realistic images, improving the depth perception and resolution of anatomic cardiac details and blood vessels compared to those of standard two-dimensional (2D) ultrasound.

A beam energy homogenizing method with total reflection beam-homogenized cavity for planar laser diagnostics

The non-uniformity of sheet-beam energy seriously limits the quantitative measurement in planar laser combustion diagnostics. A novel beam energy homogenizing method with total reflection beam-homogenized cavity is proposed to improve the uniformity of sheet-beam. The process of energy homogenizing in total reflection homogenizing cavity has been studied theoretical based on the proposed virtual light source superposition method. The influences of structure parameters and beam coupling parameters on the uniformity has been investigated. By establishing the shaping optics of the total reflection homogenizer, the sheet-beam with height of 30 mm has been achieved experimentally. The experimental results show that the uniformity of sheet-beam can be well maintained in the range of designed detection length of 60 mm. It is found that the maximum uniformity can reach up to 97.1%, which is much better than other known methods.

Calibration of brightness of virtual reality light sources based on user perception in the real environment

Accurately conveying brightness information and improving the reducibility of the perceived visual scene are important aspects of the efforts to promote the application of virtual reality (VR) in light environment research. In this study, brightness perception threshold (BPT) experiments with controlled, repeatable conditions were conducted in equivalent real and VR environments using the minimum change method. The experiments were conducted with the luminance, shape, size, and position of the light-emitting surfaces as variables, using 20 distinct surface forms. After 28 participants finished the assessment, the experimental data were analyzed using SPSS. The analysis shows that the initial luminance, shape, and size all have significant influence on the BPT in both real and VR environments, and the influence rules are consistent. The effect of the positions of the light-emitting surfaces on the BPT varies depending on the shape. Based on the BPT data, the Number of Perceptions (NOP) was proposed as an intermediate variable, and 15 brightness calibration curves for VR and real environment light sources were established. This study uses the consistency of visual brightness to establish the correspondence between the VR presentations’ brightness and the physical illumination of real scenes, which has implications for improving the accuracy of VR applications to light environment research and design.

P‐7.19: Virtual‐Point‐Light‐Source‐Based Design Method for Double Freeform Surfaces Lenses in Direct‐Lit Backlight Units

P‐7.19: Virtual‐Point‐Light‐Source‐Based Design Method for Double Freeform Surfaces Lenses in Direct‐Lit Backlight Units

Antenatal diagnosis of congenital heart disease by 3D ultrasonography using spatiotemporal image correlation with HDlive Flow and HDlive Flow silhouette rendering modes.

This pictorial review describes the assessment of a great variety of types of congenital heart disease by three-dimensional ultrasonography with spatiotemporal image correlation using HDlive and the HDlive Flow silhouette rendering mode. These technologies provide fetal heart surface patterns by using a fixed virtual light source that propagates into the tissues, permitting a detailed reconstruction of the heart structures. In this scenario, ultrasound operators can freely select a better light source position to enhance the anatomical details of the fetal heart. HDlive and the HDlive Flow silhouette rendering mode improve depth perception and the resolution of anatomic cardiac details and blood vessel walls compared to standard two-dimensional ultrasonography.

Utility of transillumination and transparency renderings in 3D transthoracic imaging.

Transillumination (TI) is a new 3D rendering tool that uses a freely movable virtual light source to enhance depth, contours, and image detail. The TI model was recently modified to allow the operator adjust the degree of transparency of both cardiac and extra-cardiac structures. While the addition of transparency was shown to significantly improve quality in 3D transesophageal imaging, this has not yet been shown for transthoracic (TTE) imaging. We prospectively studied 35 patients who underwent clinically indicated TTE with standard 3D acquisition, as well as TI with and without transparency. Six experienced echocardiographers were shown images of all three display types in random order. Each image was scored independently using a Likert Scale while assessing each of the following aspects: ability to identify anatomy or pathology, depth perception, degree of anatomic detail, and border delineation. All experts perceived an incremental value of the transparency mode, compared to TI without transparency and standard 3D rendering, in terms of ability to identify anatomy or pathology (4.15 ± 0.97 vs. 3.88 ± 0.99 vs. 2.52 ± 1.41, p < 0.01), depth perception (4.33 ± 0.78 vs. 3.88 ± 0.82 vs. 2.29 ± 1.07, p < 0.01), degree of anatomic detail (4.08 ± 1.0 vs. 3.89 ± 0.79 vs. 2.31 ± 1.08, p < 0.01), and border delineation (4.44 ± 0.80 vs. 3.90 ± 0.78 vs. 2.42 ± 1.13, p < 0.01). Compared to standard 3D and TI renderings of TTE images, the addition of transparency significantly improves both image quality and diagnostic confidence.

Slit homogenizer introduced performance gain analysis based on the Sentinel-5/UVNS spectrometer

Abstract. Spatially heterogeneous Earth radiance scenes affect the atmospheric composition measurements of high-resolution Earth observation spectrometer missions. The scene heterogeneity creates a pseudo-random deformation of the instrument spectral response function (ISRF). The ISRF is the direct link between the forward radiative transfer model, used to retrieve the atmospheric state, and the spectra measured by the instrument. Hence, distortions of the ISRF owing to radiometric inhomogeneity of the imaged Earth scene will degrade the precision of the Level-2 retrievals. Therefore, the spectral requirements of an instrument are often parameterized in the knowledge of the ISRF over non-uniform scenes in terms of shape, centroid position of the spectral channel and the full width at half maximum (FWHM). The Sentinel-5/UVNS instrument is the first push-broom spectrometer that makes use of a concept referred to as a slit homogenizer (SH) for the mitigation of spatially non-uniform scenes. This is done by employing a spectrometer slit formed by two parallel mirrors scrambling the scene in the along track direction (ALT) and hence averaging the scene contrast only in the spectral direction. The flat mirrors do not affect imaging in the across track direction (ACT) and thus preserve the spatial information in that direction. The multiple reflections inside the SH act as coherent virtual light sources and the resulting interference pattern at the SH exit plane can be described by simulations using scalar diffraction theory. By homogenizing the slit illumination, the SH strongly modifies the spectrograph pupil illumination as a function of the input scene. In this work we investigate the impact and strength of the variations of the spectrograph pupil illumination for different scene cases and quantify the impact on the ISRF stability for different types of aberration present in the spectrograph optics.

Rare double orifice mitral valve malformation associated with bicuspid aortic valve in Turner syndrome: diagnosed by a series of novel three-dimensional echocardiography and literature review

BackgroundPatients with both double orifice mitral valve (DOMV) and bicuspid aortic valve (BAV) malformation are rare. Although DOMV or BAV can be detected in some genetic syndromes, it has not been reported to simultaneously appear in Turner syndrome (TS). TrueVue, TouchVue, and TrueVue Glass are the latest technologies in advanced three-dimensional echocardiography (3DE), which is an important information supplement to two-dimensional echocardiography (2DE) for the diagnosis of congenital cardiac malformations. Herein we report the novel use of the above-mentioned technologies in the diagnosis and evaluation of a rare, combined valve malformation. Meanwhile, we also reviewed the literature for cases involving both DOMV and BAV and their association with various genetic syndromes.Case presentationWe present the case of a 5-year-old girl diagnosed with TS because of a developmental delay. DOMV and BAV were found through echocardiographic examination. Three-dimensional transthoracic echocardiography as well as a series of novel advanced techniques were applied to clearly display the spatial structure of all tiers of the mitral valve apparatus, aortic valve, and arch to facilitate an accurate diagnosis.ConclusionsThis is the first case in which both DOMV and BAV were associated with TS. Innovative TrueVue and TrueVue Glass offer unprecedented photographic stereoscopic images, while TouchVue technology greatly improved the ultrasonic diagnostic workflow and the diagnostic performance of rare valve malformations by adding virtual light sources to display realistic light-shadow effects.

Head to Head Comparison between Different 3-Dimensional Echocardiographic Rendering Tools in the Imaging of Percutaneous Edge-to-Edge Mitral Valve Repair.

MitraClip (MC) is the most common percutaneous treatment for severe mitral regurgitation (MR). An accurate two-dimensional and three-dimensional echocardiographic (3DTEE) imaging is mandatory for the optimal procedural result. Recently transillumination 3DTEE rendering (3DTr) has been introduced integrating a virtual light source into the dataset and with the addition of glass effect (3DGl) allows to adjust tissue transparency improving depth perception and anatomical structure delineation in comparison with the standard 3DTEE (3DSt). The aim of this retrospective study in 30 patients undergoing MC, was to compare 3DSt, 3DTr, and 3DGl in mitral valve (MV) evaluation and procedural result assessment. 3DTEE acquisitions obtained before and after MC were processed with 3DSt, 3DTr, and 3DGl rendering. Each reconstruction was scored for quality and for ability to recognize MV anatomy, MR origin, clip position, dimension and grasping. Imaging quality was judged good or optimal in 52%, 76%, and 96% in 3DSt, 3DTr, and 3DGl reconstructions respectively. In 26/30 patients a diagnostic incremental value was found with 3DTr vs. 3DSt and in 15/26 with 3DGl vs. 3DTr and 3DSt. Only 3DGl with perpendicular cropping of the clip allowed to visualize and measure the grasped portion of each mitral leaflets. 3DTEE imaging during MC may be improved by 3DTr and 3DGl providing a better evaluation of MV, of leaflet grasping and of residual MR jets after MC.

Real-time indirect illumination by virtual planar area lights

This paper presents a method called Virtual Planar Area Lights (VPALs) to generate single-bounce diffuse-to-diffuse indirect illumination for dynamic scenes and light sources. Different from the VPLs (Virtual Point Lights) based methods, which extract point lights from RSM (Reflective Shadow Map), our method fits RSM by many planar regions which will be directly used as virtual light sources to generate the indirect illumination. In order to reduce the illumination errors introduced by plane fitting, we propose several strategies, including an illumination-guided plane fitting algorithm, a normal correction factor and a virtual light sources reuse strategy. Our experimental results indicate that our method can achieve a good balance between the rendering performance and quality. Compared with traditional light culling and clustering methods, the rendering consumption of our algorithm is reduced by at least 67% with the similar RMSE (Root Mean Squared Error).

Imaging a unicuspid aortic valve with transillumination.

Unicuspid aortic valve (UAV) is a rare congenital malformation which portends an augmented risk of early valve degeneration. Timely detection of this cardiac valvular anomaly is crucial because a strict follow-up is warranted. Currently, the best morphological information is provided by two-dimensional echocardiography; however, its diagnostic performance has been found to be suboptimal by some anatomical features, making it tough to distinguish between UAV and bicuspid aortic valve. Transillumination is a photo-realism technique that employs the use of a virtual light source that simulates the interaction of light on 3-dimensional surfaces,improving the visualization of morphological characteristics. Our report highlights the incremental value of photo-realistic rendering and lighting source technology to better define the aortic valvemorphology.

An Improved Q-RRT* Algorithm Based on Virtual Light

The Rapidly-exploring Random Tree (RRT) algorithm is an efficient path-planning algorithm based on random sampling. The RRT* algorithm is a variant of the RRT algorithm that can achieve convergence to the optimal solution. However, it has been proven to take an infinite time to do so. An improved Quick-RRT* (Q-RRT*) algorithm based on a virtual light source is proposed in this paper to overcome this problem. The virtual light-based Q-RRT* (LQ-RRT*) takes advantage of the heuristic information generated by the virtual light on the map. In this way, the tree can find the initial solution quickly. Next, the LQ-RRT* algorithm combines the heuristic information with the optimization capability of the Q-RRT* algorithm to find the approximate optimal solution. LQ-RRT* further optimizes the sampling space compared with the Q-RRT* algorithm and improves the sampling efficiency. The efficiency of the algorithm is verified by comparison experiments in different simulation environments. The results show that the proposed algorithm can converge to the approximate optimal solution in less time and with lower memory consumption.

Diagnostic Accuracy of Transillumination in Mitral Valve Prolapse: Side-by-Side Comparison of Standard Transthoracic Three-Dimensional Echocardiography against Surgical Findings

In patients with mitral valve prolapse (MVP) eligible for surgery, three-dimensional echocardiographic (3DE) imaging is routinely used for preoperative assessment. 1 Baumgartner H. Falk V. Bax J.J. De Bonis M. Hamm C. Holm P.J. et al. 2017 ESC/EACTS guidelines for the management of valvular heart disease. Eur Heart J. 2017; 38: 2739-2791 Crossref PubMed Scopus (2) Google Scholar ,2 Nishimura R.A. Otto C.M. Bonow R.O. Carabello B.A. Erwin J.P. Fleisher L.A. et al. 2017 AHA/ACC focused update of the 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2017; 70: 252-289 Crossref PubMed Scopus (1731) Google Scholar Despite the worldwide use of transesophageal echocardiography in this context, transthoracic echocardiographic (TTE) imaging allows accurate noninvasive evaluation of mitral valve (MV) anatomy and pathology. 3 Gripari P. Mapelli M. Bellacosa I. Piazzese C. Milo M. Fusini L. et al. Transthoracic echocardiography in patients undergoing mitral valve repair: comparison of new transthoracic 3D techniques to 2D transoesophageal echocardiography in the localization of mitral valve prolapse. Int J Cardiovasc Imaging. 2018; 34: 1099-1107 Crossref PubMed Scopus (10) Google Scholar , 4 Tamborini G. Muratori M. Maltagliati A. Galli C.A. Naliato M. Zanobini M. et al. Pre-operative transthoracic real-time three-dimensional echocardiography in patients undergoing mitral valve repair: accuracy in cases with simple vs. complex prolapse lesions. Eur J Echocardiogr. 2010; 11: 778-785 Crossref PubMed Scopus (43) Google Scholar , 5 Pepi M. Tamborini G. Maltagliati A. Galli C.A. Sisillo E. Salvi L. et al. Head-to-head comparison of two- and three-dimensional transthoracic and transesophageal echocardiography in the localization of mitral valve prolapse. J Am Coll Cardiol. 2006; 48: 2524-2530 Crossref PubMed Scopus (196) Google Scholar Transillumination (TI) is a new three-dimensional tool that improves the visualization of cardiac structures due to shadow effects achieved by the use of a virtual light source. 6 Genovese D. Addetia K. Kebed K. Kruse E. Yamat M. Narang A. et al. First clinical experience with 3-dimensional echocardiographic transillumination rendering. JACC Cardiovasc Imaging. 2019; 12: 1868-1871 Crossref PubMed Scopus (20) Google Scholar We aimed to compare the diagnostic accuracy of TTE TI side by side with standard 3DE (s3DE) display in patients undergoing surgery for MVP. Surgical valve inspection was used as a reference standard, even though surgery allows only static MV assessment. 3 Gripari P. Mapelli M. Bellacosa I. Piazzese C. Milo M. Fusini L. et al. Transthoracic echocardiography in patients undergoing mitral valve repair: comparison of new transthoracic 3D techniques to 2D transoesophageal echocardiography in the localization of mitral valve prolapse. Int J Cardiovasc Imaging. 2018; 34: 1099-1107 Crossref PubMed Scopus (10) Google Scholar , 4 Tamborini G. Muratori M. Maltagliati A. Galli C.A. Naliato M. Zanobini M. et al. Pre-operative transthoracic real-time three-dimensional echocardiography in patients undergoing mitral valve repair: accuracy in cases with simple vs. complex prolapse lesions. Eur J Echocardiogr. 2010; 11: 778-785 Crossref PubMed Scopus (43) Google Scholar , 5 Pepi M. Tamborini G. Maltagliati A. Galli C.A. Sisillo E. Salvi L. et al. Head-to-head comparison of two- and three-dimensional transthoracic and transesophageal echocardiography in the localization of mitral valve prolapse. J Am Coll Cardiol. 2006; 48: 2524-2530 Crossref PubMed Scopus (196) Google Scholar

Detection of real-time augmented reality scene light sources and construction of photorealis tic rendering framework

In this paper, the main network of multi-channel light sources is improved, so that multi-channel pictures can be fused for joint training. Secondly, for high-resolution detection pictures, the huge memory consumption leads to a reduction in batches and then affects the model distribution. Group regularization is adopted. We can still train the model normally in small batches; then, combined with the method of the regional candidate network, the final detection accuracy and the accuracy of the candidate frame regression are improved. Finally, through in-depth analysis, based on image lighting technology and physical-based rendering theory, the requirements for lighting effects and performance limitations, combined with a variety of image enhancement technologies, such as gamma correction, HDR, and these technologies used in Java. Real-time lighting algorithms that currently run efficiently on mainstream PCs. The algorithm can be well integrated into the existing rasterization rendering pipeline, while into account better lighting effects and higher operating efficiency. Finally, the lighting effects achieved by the algorithm are tested and compared through experiments. This algorithm not only achieves a very good light and shadow effect when rendering virtual objects with a real scene as the background but also can meet the realistic rendering of picture frames in more complex scenes. Rate requirements. The experimental results show that the virtual light source automatically generated by this algorithm can approximate the lighting of the real scene, and the virtual object and the real object can produce approximately consistent lighting effects in an augmented reality environment with one or more real light sources.

Improved Delineation of Cardiac Pathology Using a Novel Three-Dimensional Echocardiographic Tissue Transparency Tool

Accurate visualization of cardiac valves and lesions by three-dimensional (3D) echocardiography is integral for optimal guidance of structural procedures and appropriate selection of closure devices. A new 3D rendering tool known as transillumination (TI), which integrates a virtual light source into the data set, was recently reported to effectively enhance depth perception and orifice definition. We hypothesized that adding the ability to adjust transparency to this tool would result in improved visualization and delineation of anatomy and pathology and improved localization of regurgitant jets compared with TI without transparency and standard 3D rendering. We prospectively studied 30 patients with a spectrum of structural heart disease who underwent 3D transesophageal imaging (EPIQ system, Philips) with standard acquisition and TI with and without the transparency feature. Six experienced cardiologists and sonographers were shown randomized images of all three display types in a blinded fashion. Each image was scored independently by all experts using a Likert scale from 1 to 5, while assessing each of the following aspects: (1) ability to recognize anatomy, (2) ability to identify pathology, including regurgitant jet origin, (3) depth perception, and (4) quality of border delineation. TI images with transparency were successfully obtained in all cases. All experts perceived an incremental value of the transparency mode, compared with TI without transparency and standard 3D rendering, in terms of ability to recognize anatomy (respective scores: 4.5±1.1 vs 4.1±1.1 vs 3.6±1.1, P<.05), ability to identify pathology (4.1±1.1 vs 3.9±1.2 vs 3.3±1, P<.05), depth perception (4.6±0.7 vs 4.1±0.8 vs 3.2±1.0, P<.05), and border delineation (4.6±0.8 vs 4.1±1.0 vs 3.1±1.1, P<.05). The addition of the transparency mode to TI rendering significantly improves the diagnostic and clinical utility of 3D echocardiography and has the potential to markedly enhance echocardiographic guidance of cardiac structural interventions.

Phototropism rapidly exploring random tree: An efficient rapidly exploring random tree approach based on the phototropism of plants

Inspired by the phototropism of plants, a novel variant of the rapidly exploring random tree algorithm as called phototropism rapidly exploring random tree is proposed. The phototropism rapidly exploring random tree algorithm expands less tree nodes during the exploration period and has shorter path length than the original rapidly exploring random tree algorithm. In the algorithm, a virtual light source is set up at the goal point, and a light beam propagation method is adopted on the map to generate a map of light intensity distribution. The phototropism rapidly exploring random tree expands its node toward the space where the light intensity is higher, while the original rapidly exploring random tree expands its node based on the uniform sampling strategy. The performance of the phototropism rapidly exploring random tree is tested in three scenarios which include the simulation environment and the real-world environment. The experimental results show that the proposed phototropism rapidly exploring random tree algorithm has a higher sampling efficiency than the original rapidly exploring random tree, and the path length is close to the optimal solution of the rapidly exploring random tree* algorithm without considering the non-holonomic constraint.

Echocardiographic photorealistic imaging of leiomyomatosis intravascularis

We present a case of patient with leiomyomatosis intravascularis. To diagnose, we used 3D photorealistic imaging which allowed us better visualisation of pathological structures as well as planning the surgical procedure in greater detail. The main advantage of this technique is the possibility to move the virtual light source and thus visualize the specific part of the heart.

Optical phase mining by adjustable spatial differentiator

Phase is a fundamental resource for optical imaging but cannot be directly observed with intensity measurements. The existing methods to quantify a phase distribution rely on complex devices and structures. Here we experimentally demonstrate a phase mining method based on so-called adjustable spatial differentiation, just generally by analyzing the polarization in light reflection on a single planar dielectric interface. With introducing an adjustable bias, we create a virtual light source to render the measured images with a shadow-cast effect. We further successfully recover the phase distribution of a transparent object from the virtual shadowed images. Without any dependence on resonance or material dispersion, this method directly stems from the intrinsic properties of light and can be generally extended to a board frequency range.

Use of a photo-realism 3D rendering technique to enhance echocardiographic visualization of the anatomical details during beating-heart mitral valve repair.

The NeoChord procedure is an innovative microinvasive, transventricular, beating-heart chordal replacement technique for patients with severe degenerative mitral valve regurgitation resulting from prolapsed or flail leaflets. Use of three-dimensional (3D) transoesophageal echocardiographic imaging is crucial to the physician operator for device navigation during the procedure and to assess the functional results of the repair at the end of the procedure. Photo-realistic, 3D rendering techniques have been recently developed for medical use. Philips TrueVue (Philips Healthcare, Eindhoven, NL) is a photo-realism technique that employs the use of a virtual light source that simulates the interaction of light on 3-dimensional surfaces. Use of photo-realism techniques, in conjunction with 3D echocardiography, improves the visualization of morphological characteristics of the mitral valve before, during, and after beating-heart mitral valve repair procedures.

Rendering a virtual light source to seem like a realistic light source in an electronic display: A critical band of luminance gradients for the perception of self-luminosity

It is a great challenge to present realistic light sources in a virtual environment given the limited luminance range of an electronic display. Previous studies show that a glare illusion can enhance the perceived luminance of an area, which is an effective way to improve the realism of light sources in virtual environments. However, it is unclear what kinds of luminance gradients are appropriate for generating virtual light sources. In this study, we investigated the quantitative rule governing the perception of self-luminosity and applied the rule to improve the fidelity of light sources in virtual environments. In particular, light spots with different luminance gradients were presented on a liquid-crystal display (LCD). The participants were asked to report whether or not a luminance spot looked like a self-luminous light source. The probability of the spot being identified as a light source was calculated at each luminance gradient. We observed a critical band of luminance gradients which are a range of power-law exponent. Once the luminance gradient of an image fell into that range, the image was mainly perceived as self-luminosity. The critical band could not be explained by either the local luminance contrast or the total luminance energy. Interestingly, natural image statistics showed that the band matched with the luminance gradients of light sources in natural images. The perception of self-luminosity depends on the specific luminance gradients which are accumulated by human perceptual experience to light sources on natural images. Moreover, we generated virtual light sources with different surrounding luminance gradients and the gradients around the peak of the critical band won the highest rating of perceptual fidelity. These results provide a quantitative description of the perception of self-luminosity, which offers a guideline of how to improve the fidelity when rendering light sources in a virtual environment.