A touring machine: Prototyping 3D mobile augmented reality systems for exploring the urban environment

We describe a prototype system that combines the overlaid 3D graphics of augmented reality with the untethered freedom of mobile computing. The goal is to explore how these two technologies might together make possible wearable computer systems that can support users in their everyday interactions with the world. We introduce an application that presents information about our university's campus, using a head-tracked, see-through, head-worn, 3D display, and an untracked, opaque, hand-held, 2D display with stylus and trackpad. We provide an illustrated explanation of how our prototype is used, and describe our rationale behind designing its software infrastructure and selecting the hardware on which it runs.     

The CMU pose, illumination, and expression database

In the Fall of 2000, we collected a database of more than 40,000 facial images of 68 people. Using the Carnegie Mellon University 3D Room, we imaged each person across 13 different poses, under 43 different illumination conditions, and with four different expressions. We call this the CMU pose, illumination, and expression (PIE) database. We describe the imaging hardware, the collection procedure, the organization of the images, several possible uses, and how to obtain the database.     

Real-time detection of colored objects in multiple camera streams with off-the-shelf hardware components

We describe RTblob, a high speed vision system that detects objects in cluttered scenes based on their color and shape at a speed of over 800 frames/s. Because the system is available as open-source software and relies only on off-the-shelf PC hardware components, it can provide the basis for multiple application scenarios. As an illustrative example, we show how RTblob can be used in a robotic table tennis scenario to estimate ball trajectories through 3D space simultaneously from four cameras images at a speed of 200 Hz.     

Multidimensional transfer functions for interactive volume rendering

Most direct volume renderings produced today employ 1D transfer functions which assign color and opacity to the volume based solely on the single scalar quantity which comprises the data set. Though they have not received widespread attention, multi-dimensional transfer functions are a very effective way to extract materials and their boundaries for both scalar and multivariate data. However, identifying good transfer functions is difficult enough in 1D, let alone 2D or 3D. This paper demonstrates an important class of 3D transfer functions for scalar data, and describes the application of multi-dimensional transfer functions to multivariate data. We present a set of direct manipulation widgets that make specifying such transfer functions intuitive and convenient. We also describe how to use modern graphics hardware to both interactively render with multidimensional transfer functions and to provide interactive shadows for volumes. The transfer functions, widgets and hardware combine to form a powerful system for interactive volume exploration.     

Memory‐Efficient Interactive Online Reconstruction From Depth Image Streams

We describe how the pipeline for 3D online reconstruction using commodity depth and image scanning hardware can be made scalable for large spatial extents and high scanning resolutions. Our modified pipeline requires less than 10% of the memory that is required by previous approaches at similar speed and resolution. To achieve this, we avoid storing a 3D distance field and weight map during online scene reconstruction. Instead, surface samples are binned into a high‐resolution binary voxel grid. This grid is used in combination with caching and deferred processing of depth images to reconstruct the scene geometry. For pose estimation, GPU ray‐casting is performed on the binary voxel grid. A one‐to‐one comparison to level‐set ray‐casting in a distance volume indicates slightly lower pose accuracy. To enable unlimited spatial extents and store acquired samples at the appropriate level of detail, we combine a hash map with a hierarchical tree representation.     

A Survey of 3D Interaction Techniques

Recent gains in the performance of 3D graphics hardware and rendering systems have not been matched by a corresponding improvement in our knowledge of how to interact with the virtual environments we create; therefore there is a need to examine these further if we are to improve the overall quality of our interactive 3D systems. This paper examines some of the interaction techniques which have been developed for object manipulation, navigation and application control in 3D virtual environments. The use of both mouse-based techniques and 3D input devices is considered, along with the role of feedback and some aspects of tools and widgets.     

Efficient visualization of 3D models on hardware-limited portable devices

Managing the geometry of a 3D scene efficiently is a key aspect of an interactive 3D application. This aspect is more important if we target at portable devices, which have limited hardware capabilities. Developing new means for improving the interaction with 3D content in mobile devices is key. The aim of this work is to present a technique which can manage the level-of-detail of 3D meshes in portable devices. This solution has been devised considering the restrictions that this kind of devices poses. The results section shows how the integration has been successful while obtaining good performance.     

Using motion to illustrate static 3D shape-kinetic visualization

In this paper, we present a novel visualization technique-kinetic visualization-that uses motion along a surface to aid in the perception of 3D shape and structure of static objects. The method uses particle systems, with rules such that particles flow over the surface of an object to not only bring out, but also attract attention to information on a shape that might not be readily visible with a conventional rendering method which uses lighting and view changes. Replacing still images with animations in this fashion, we demonstrate with both surface and volumetric models in the accompanying videos that, in many cases, the resulting visualizations effectively enhance the perception of three-dimensional shape and structure. We also describe how, for both types of data, a texture-based representation of this motion can be used for interactive visualization using PC graphics hardware. Finally, the results of a user study that we have conducted are presented, which show evidence that the supplemental motion cues can be helpful.     

Importance Driven Texture Coordinate Optimization

Traditionally, texture coordinates have been generated based solely on the model's geometry, often even before a model's textures have been created. With the arrival of new technologies, such as 3D paint programs, weaknesses of a static optimization pre-process are becoming apparent. These weaknesses arise from constructing a parameterization based solely on the model's geometry, ignoring the fact that detail is not uniformly spaced throughout the texture space. In fact, certain regions of the texture are more important than other regions. In this paper we introduce the notion of the "importance map" and describe how importance values are derived from both intrinsic properties of the texture and user-guided highlights. Furthermore, we describe how importance maps are used to drive the texture coordinate optimization. Finally, we show how this optimization process can be integrated into a 3D painting environment, enabling periodic optimization at any stage of texture design.     

A scalable architecture for 3D map navigation on mobile devices

Mobile devices such as smart phones or tablets are rapidly increasing their graphics and networking capabilities. However, real-time visualization of 3D maps is still a challenging task to accomplish on such limited devices. In this paper, we describe the principles involved in the design and development of a scalable client–server architecture for delivering 3D maps over wireless networks to mobile devices. We have developed a hybrid adaptive streaming and rendering method that distributes the 3D map rendering task between the mobile clients and a remote server. This architecture provides support for efficient delivery of 3D contents to mobile clients according to their capabilities. As a proof of concept, we have implemented a prototype and carried out exhaustive experiments considering different scenarios and hundreds of concurrent connected clients. The analysis of the server workload and the mobile clients performance show that our architecture achieves a great scalability and performance even when using low-end hardware.     

DM9000AE及其在嵌入式以太网中的应用

介绍了一种以ARM微处理器LPC2106为核心的嵌入式以太网接口设计方法.对系统软硬件设计进行了介绍.硬件部分介绍了系统的硬件组成以及网络控制器DM9000AE的性能和工作原理.系统软件设计介绍了IwIP TCP/IP协议的移植以及应该注意的问题.在此软硬件基础上完成了一种轻型的,性价比高的嵌入式以太网接口卡的设计.     

Silicon Debug of a PowerPC™ Microprocessor Using Model Checking

When silicon is available, newly designed microprocessors are tested in specially equipped hardware laboratories, where real applications can be run at hardware speeds. However, the large volumes of code being run, plus the limited access to the internal nodes of the chip, make it very difficult to characterize the nature of any failures that occur.In this paper, we describe how temporal logic model checking was used to quickly characterize a design error exhibited during hardware testing of a PowerPC microprocessor. We outline the conditions under which model checking can efficiently characterize such failures, and show how the particular error we detected could have been revealed early in the design cycle, by model checking a short and simple correctness specification. We discuss the implications of this for verification methodologies over the full design cycle.     

prialt in Handel-C: an operational semantics

We describe an operational semantics for the hardware compilation language Handel-C [7], which is a C-like language with channel communication and parallel constructs which compiles down to mainly synchronously clocked hardware. The work in this paper builds on previous work describing the semantics of the “prialt” construct within Handel-C [5] and a denotational semantics for part of the language [6]. We describe a key subset of the language and show how a design decision for the real language, namely that default guards in a prialt statement executed in “zero-time”, has consequences for the complexity of the operational semantics. We present the operational semantics, along with a revised and completed prialt semantics, indicating clearly the interface between them. We then describe a notion of observational equivalence and present an example illustrating how we handle the complexity of nested prialts in default guards.     

Extending an ICT4D Computer Re-use Model with E-waste Handling Activities: A Case Study

This paper illustrates how a computer re-use model can be extended to deal with e-waste challenges. First, we describe the re-use of computers as a factor that can help bridge the global digital divide. In an ICT4D context, refurbished computers can be used in developing countries. We describe and illustrate the operating model of such a computer re-use organization, highlighting the different components and interactions of the operating model. Next, we discuss how e-waste puts this computer re-use model under pressure. We argue that the sustainability of computer re-use in an ICT4D context is seriously impacted by this increasing e-waste problem. Finally, we describe how a computer re-use model can be extended and complemented with e-waste handling activities to retain positive effects in an ICT4D context. The paper is based on a single case study.     

基于对焦原理的三维成像方法

传统数字成像技术只能获取目标的二维影像,难以精确描述目标的空间形状和距离信息。介绍了一种通过分析对焦数据来获取目标三维信息的方法。该方法基于光学成像原理,不需要特别的硬件设备,可以方便地通过软件方法在现有数字成像系统中加以实现。