Joshua Napoli

100-million-voxel volumetric display

A 360-degree-viewable volumetric 3-D display has been developed by Actuality Systems, Inc. It has a resolution of 768 x 768 x 198, has a 24 Hz refresh rate, contains an embedded graphics processing system, and uses dithering methods to create images of 3-bit to 21-bit color. The 3-D display system is a visualization platform, comprised of a combination of hardware and software designed for ease-of-integration into existing visualization systems. The system design is briefly recounted. Key enhancements are described, such as the development of a volumetric visualization software platform. Examples are given which guide the system engineer who needs to include a volumetric display into a visualization solution.

Occlusion-capable multiview volumetric three-dimensional display

Volumetric 3D displays are frequently purported to lack the ability to reconstruct scenes with viewer-position-dependent effects such as occlusion. To counter these claims, a swept-screen 198-view horizontal-parallax-only 3D display is reported here that is capable of viewer-position-dependent effects. A digital projector illuminates a rotating vertical diffuser with a series of multiperspective 768 x 768 pixel renderings of a 3D scene. Evidence of near-far object occlusion is reported. The aggregate virtual screen surface for a stationary observer is described, as are guidelines to construct a full-parallax system and the theoretical ability of the present system to project imagery outside of the volume swept by the screen.

Spatial 3-D Infrastructure: Display-Independent Software Framework, High-Speed Rendering Electronics, and Several New Displays

We present a software and hardware foundation to enable the rapid adoption of 3-D displays. Different 3-D displays - such as multiplanar, multiview, and electroholographic displays - naturally require different rendering methods. The adoption of these displays in the marketplace will be accelerated by a common software framework. The authors designed the SpatialGL API, a new rendering framework that unifies these display methods under one interface. SpatialGL enables complementary visualization assets to coexist through a uniform infrastructure. Also, SpatialGL supports legacy interfaces such as the OpenGL API. The authors’ first implementation of SpatialGL uses multiview and multislice rendering algorithms to exploit the performance of modern graphics processing units (GPUs) to enable real-time visualization of 3-D graphics from medical imaging, oil & gas exploration, and homeland security. At the time of writing, SpatialGL runs on COTS workstations (both Windows and Linux) and on Actuality’s high-performance embedded computational engine that couples an NVIDIA GeForce 6800 Ultra GPU, an AMD Athlon 64 processor, and a proprietary, high-speed, programmable volumetric frame buffer that interfaces to a 1024 x 768 x 3 digital projector. Progress is illustrated using an off-the-shelf multiview display, Actuality’s multiplanar Perspecta Spatial 3D System, and an experimental multiview display. The experimental display is a quasi-holographic view-sequential system that generates aerial imagery measuring 30 mm x 25 mm x 25 mm, providing 198 horizontal views.

Imaging artifact precompensation for spatially multiplexed 3-D displays

We describe a projection system that presents a 20 megapixel image using a single XGA SLM and time-division multiplexing. The system can be configured as a high-resolution 2-D display or a highly multi-view horizontal parallax display. In this paper, we present a technique for characterizing the light transport function of the display and for precompensating the image for the measured transport function. The techniques can improve the effective quality of the display without modifying its optics. Precompensation is achieved by approximately solving a quadratic optimization problem. Compared to a linear filter, this technique is not limited by a fixed kernel size and can propagate image detail to all related pixels. Large pixel-count images are supported through dividing the problem into blocks. A remedy for blocking artifacts is given. Results of the algorithm are presented based on simulations of a display design. The display characterization method is suitable for experimental designs that may be dim and imperfectly aligned. Simulated results of the characterization and precompensation process are presented. RMS and qualitative improvement of display image quality are demonstrated.

Radiation therapy planning using a volumetric 3-D display: PerspectaRAD

We describe PerspectaRAD, the first tool for the review and modification of external-beam radiation therapy treatment plans with a volumetric three-dimensional display (Perspecta 1.9, Actuality Medical, Bedford, MA, USA) and a dedicated software application (PerspectaRAD, Actuality Medical). We summarize multi-institution retrospective studies that compare the systems efficacy to the incumbent 2-D display-based workflow. Contributions include: visualizing the treatment plan in a volumetric 3-D display, modifying the beam locations and performing point-and-click measurement in 3-D with a 3-D physical interface, and simultaneously viewing volumetric projections of the native CT data and isodose contours. The plans are synchronized with the hospital treatment planning system, Pinnacle3 (Philips Medical, WI, USA). In the largest of five studies, 33 plans were retrospectively randomized and replanned at three institutions, including 12 brain, 10 lung, and 11 abdomen / pelvis. The PerspectaRAD plan was as good as or better than plans created without PerspectaRAD 70% of the time. Radiation overdose regions were more likely to be obvious inside the target volume than when reviewed in the 2-D display alone. However, the planning time was longer with PerspectaRAD. The data demonstrate that PerspectaRAD facilitates the use of non-coplanar beams and has significant potential to achieve better plan quality in radiation therapy.