Realistic Rendering in "Details".

Rendering is far from solved. Even today, the rendered results still look artificial and overly perfect. To make rendering more realistic, we need details. However, rendering a complex surface with lots of details is far from easy. Traditionally, the surface microstructure is approximated using a smooth statistical distribution, but this ignores all the details on the surface, completely eliminating the "glinty" visual effects that are easily observable in the real world. While modeling the actual surface microstructure is possible, the resulting rendering problem is prohibitively expensive using Monte Carlo point sampling. We consider the highly complicated distribution of normals on a surface patch seen through a single pixel, and evaluate this actual distribution efficiently with closed-form solutions, in both geometric and wave optics. Results show complicated, temporally varying glints from materials such as bumpy plastics, brushed and scratched metals, metallic paint and ocean waves-bringing the interesting and important details to Computer Graphics for the first time.

Low-Latency Rendering With Dataflow Architectures.

Recent years have seen a resurgence of virtual reality (VR), sparked by the repurposing of low-cost COTS components. VR aims to generate stimuli that appear to come from a source other than the interface through which they are delivered. The synthetic stimuli replace real-world stimuli, and transport the user to another, perhaps imaginary, "place." To do this, we must overcome many challenges, often related to matching the synthetic stimuli to the expectations and behavior of the real world. One way in which the stimuli can fail is its latency-- the time between a user's action and the computer's response. We constructed a novel VR renderer, that optimized latency above all else. Our prototype allowed us to explore how latency affects human-computer interaction. We had to completely reconsider the interaction between time, space, and synchronization on displays and in the traditional graphics pipeline. Using a specialized architecture--dataflow computing--we combined consumer, industrial, and prototype components to create an integrated 1:1 room-scale VR system with a latency of under 3 ms. While this was prototype hardware, the considerations in achieving this performance inform the design of future VR pipelines, and our human factors studies have provided new and sometimes surprising contributions to the body of knowledge on latency in HCI.

Visibility, Topology, and Inertia: New Methods in Flow Visualization.

In this article, we address three different topics in scientific visualization. The first part introduces optimization strategies that determine the visibility of line and surface geometry, such that a balance between occlusion avoidance and preservation of context is found. The second part proposes new methods for the visualization of time-dependent fluid flows, including the accurate depiction of Lagrangian scalar fields, as well as a new category of vortex identification methods. The third part introduces finite-sized particles as new application area for flow visualization, covering geometry-based methods, particle separation, topology, vortex corelines, and the determination of the origin of finite-sized particles.

Topological Modeling for Vector Graphics.

Vector graphics refers to the use of geometrical primitives, such as Bézier curves, to represent digital images. It is becoming increasingly popular among graphic designers who need to deliver resolution-independent content that looks sharp across all types of desktop and mobile devices, or need to support user interactivity and animation. Unfortunately, most vector graphics tools today have many limitations, such as the inability to represent shapes sharing a common edge. In my doctoral dissertation, we address this issue by developing a novel data structure, called the vector graphics complex, which supports fundamental topological modeling operations for vector graphics illustrations. We also extend this data structure to animation, allowing features of a connected drawing to merge, split, appear, or disappear at desired times via keyframes that introduce the desired topological change. The resulting space-time continuous complex directly captures the time-varying topological structure, and allows features to be readily edited in both space and time in a way that reflects the intent of the drawing.

Successful in vivo recovery and extended storage of additive solution (AS)-5 red blood cells after deglycerolization and resuspension in AS-3 for 15 days with an automated closed system.

BACKGROUND: Previously, cryopreserved red blood cell (RBC) units derived from CPD/AS-5 whole-blood (WB) collections have been limited to 24 hours postthaw storage (1-6 degrees C). STUDY DESIGN AND METHODS: Sixty-four leukoreduced (LR) and 54 nonleukoreduced (NLR) AS-5 (n = 118) RBC units from 500-mL WB collections were stored for 6 days, glycerolized, frozen (-70 +/- 5 degrees C) for at least 14 days, thawed, deglycerolized, and stored (1-6 degrees C) for 15 days resuspended in AS-3, using an automated closed-system cell processor (ACP 215, Haemonetics). Frozen units were stored in either ethylene vinyl acetate (EVA) or polyvinylchloride (PVC) bags. In vitro parameters were tested in all units 15 days after deglycerolization. In vivo 24-hour recovery was measured in 77 of 118 donors. RESULTS: Postdeglycerolization in vitro RBC mass recoveries (mean +/- SD) were 96.8 +/- 5.7 and 94.7 +/- 5.6% for EVA LR and NLR units, respectively, and 97.3 +/- 6.2 and 94.7 +/- 6.2% for PVC LR and NLR units, based on unit weight and hematocrit after sampling for in vitro testing, immediately before glycerolization. Hemoglobin content (g/unit, mean +/- SD) after deglycerolization was 40.4 +/- 5.6 and 42.6 +/- 6.0 for EVA LR and NLR units, respectively, and 40.7 +/- 4.8 and 43.0 +/- 7.7 for PVC LR and NLR units. Hemolysis was 0.61 +/- 0.23 and 0.54 +/- 0.16% for EVA LR and NLR units, and 0.47 +/- 0.14 and 0.43 +/- 0.12% for PVC LR and NLR units. In vivo 24-hour recoveries on Day 15 were 83.0 +/- 6.7% (PVC NLR) up to 86.2 +/- 5.7% (EVA NLR). CONCLUSION: With processing on the ACP 215 system, CPD/AS-5 LR and NLR thawed RBC units can be stored for up to 14 days after frozen storage at -65 degrees C or colder in EVA or PVC bags with acceptable in vivo and in vitro RBC quality.

Viability and function of 8-day-stored apheresis platelets.

BACKGROUND: Methods of bacterial detection and pathogen inactivation of platelets (PLTs) may allow extended storage of PLTs as long as PLT quality is maintained. STUDY DESIGN AND METHODS: Twenty normal volunteers had their PLTs collected with an apheresis machine (Haemonetics Corp.). A variety of in vitro PLT function and metabolic assays were performed both on Day 0 and after 8 days of storage. On Day 8, a small blood sample was drawn from each donor to obtain fresh PLTs. The fresh and stored autologous PLTs were labeled with either (51)Cr or (111)In, and the radiolabeled PLTs were transfused. Posttransfusion serial blood samples were drawn to determine the relative posttransfusion recoveries and survivals of the fresh versus the stored PLTs. RESULTS: Although the in vitro assays showed some differences between the two trial sites, the results were generally within the ranges expected for fresh and stored PLTs. Overall, PLT recoveries averaged 66 +/- 16 percent versus 53 +/- 20 percent and survivals averaged 8.5 +/- 1.6 days versus 5.6 +/- 1.6 days, respectively, for fresh compared to 8-day-stored PLTs. There were no significant differences in the in vivo PLT data between the trial sites or based on the radiolabel used for the measurements. CONCLUSION: After 8 days of storage, the in vivo posttransfusion recovery and survival of autologous Haemonetics apheresis PLTs meet the proposed standards for poststorage PLT quality.

Development and validation of radioligand binding assays to measure total, IgA, IgE, IgG, and IgM insulin antibodies in human serum.

Radioligand binding assays for total and Ig classes of insulin antibodies (IAB) were developed and validated. For each assay, insulin-extracted serum samples were incubated with radiolabeled insulin in the presence and absence of high levels of unlabeled insulin to determine nonspecific binding and total binding, respectively. To measure total IAB, antibody-bound insulin was precipitated with a polyethylene glycol solution, washed, and counted in a gamma-counter. To measure IgG IAB, samples were treated with protein G-Sepharose beads, centrifuged, washed, and counted. For the measurement of IgA, IgE, and IgM IAB, IgG was removed from the samples and treated with anti-IgA, -IgE, or -IgM conjugated to Sepharose beads, centrifuged, washed, and counted. The acid/charcoal extraction of bound and unbound insulin from serum samples was optimized. Specificity and binding capacity of the protein G and antibody-bound beads were evaluated and optimized. The linear region of the total and IgG IAB assays was determined using serum samples containing high levels of insulin antibodies. The limit of quantitation, limit of detection, and precision for all the assays were also determined.