14933318
Beyond 2D images: effective 3D imaging for library materials
Significant efforts are being made to digitize rare and valuable library materials, with the goal of providing patrons and historians digital facsimiles that capture the "look and feel" of the original materials. This is often done by digitally photographing the materials and making high resolution 2D images available. The underlying assumption is that the objects are flat. However, older materials may not be flat in practice, being warped and crinkled due to decay, neglect, accident and the passing of time. In such cases, 2D imaging is insufficient to capture the "look and feel" of the original. For these materials, 3D acquisition is necessary to create a realistic facsimile. This paper outlines a technique for capturing an accurate 3D representation of library materials which can be integrated directly into current digitization setups. This will allow digitization efforts to provide patrons with more realistic digital facsimile of library materials.
37436531
A practical and flexible tiled display system
Computer graphics and high-resolution digital imagery are becoming increasingly pervasive in communities not traditionally associated with graphics. Commodity graphics cards and digital cameras, along with powerful modeling software, allow organizations such as libraries, museums, and small businesses to produce expressive and realistic computer generated imagery, far surpassing the capabilities of current desktop monitors. What remains elusive to these groups is access to affordable and easy to use large format display technology. We present a practical system for deploying flexible projector based tiled displays. Our framework integrates two key components: (1) self-calibrating display geometry with real-time geometric correction and (2) PC-based distributed rendering that supports an established graphics API. Our system's display geometry is easy to configure and reconfigure, accommodates casually tiled projectors and arbitrary display surfaces, and can be operational in a matter of minutes. In addition, the underlying distributed rendering architecture (WireGL) is transparent to existing OpenGL applications, requiring no custom APIs or re-compilation of existing OpenGL executables. In short, we present a practical and flexible low-cost tiled display system that is simple to deploy and easy to operate.
17720018
Conformal deskewing of non-planar documents
This paper presents an approach that uses conformal mapping to parameterize a document's 3D shape to a 2D plane. Using this conformal parametrization, a restorative mapping between an image of the distorted document and a "flattened" representation of the document can be computed and used to deskew the image. Our experiments show that arbitrarily distorted documents can be restored to within a single pixel of their true planar format. In addition, surface points can be constrained to map to specified locations in the restored 2D plane.
41367426
Incorporating Geometric Registration With Pc-Cluster Rendering For Flexible Tiled Displays
We describe a display system that automatically registers an array of casually positioned projectors and drives the display with a PC cluster. The display system uses a camera to compute the necessary transformations to geometrically align multiple overlapping projectors. Geometric alignment is realized through real-time corrective warping applied in the rendering pipeline. This combination of camera-aided display alignment with the PC-cluster rendering engine provides a display system that is easy to configure and reconfigure, accommodates casually tiled projectors and arbitrary display surfaces, and can be operational in a very short period of time.
1120694
Image restoration of arbitrarily warped documents
We present a framework for acquiring and restoring images of warped documents. The purpose of our restoration is to create a planar representation of a once planar document that has undergone an arbitrary and unknown rigid deformation. To accomplish this restoration, our framework acquires and flattens the 3D shape of a warped document to determine a nonlinear image transform that can correct for image distortion caused by the document's shape. Our framework is designed for use in library and museum digitization efforts where very old and badly damaged manuscripts are imaged.
10099377
Geometric and photometric restoration of distorted documents
We present a system to restore the 2D content printed on distorted documents. Our system works by acquiring a 3D scan of the document's surface together with a high-resolution image. Using the 3D surface information and the 2D image, we can ameliorate unwanted surface distortion and effects from non-uniform illumination. Our system can process arbitrary geometric distortions, not requiring any pre-assumed parametric models for the document's geometry. The illumination correction uses the 3D shape to distinguish content edges from illumination edges to recover the 2D content's reflectance image while making no assumptions about light sources and their positions. Results are shown for real objects, demonstrating a complete framework capable of restoring geometric and photometric artifacts on distorted documents
12462654
3D Model Acquisition by Tracking 2D Wireframes
This paper presents a semi-automatic wireframe acquisition system. The system uses real-time (25Hz) tracking of a user specified 2D wireframe and intermittent camera pose parameters to accumulate 3D position information. The 2D tracking framework enables the application of model-based constraints in an intuitive way which interacts naturally with the Kalman filter formulation used. In particular, this is used to introduce feedback from the current 3D shape estimate to improve the robustness of the 2D tracking. The scheme allows wireframe models of simple edge based objects to be built in around 5 minutes.
1418505
Small Subunit Ribosomal RNA Modeling Using Stochastic Context-Free Grammars
We introduce a model based on stochastic context-free grammars (SCFGs) that can construct small subunit ribosomal RNA (SSU rRNA) multiple alignments. The method takes into account both primary sequence and secondary structure basepairing interactions. We show that this method produces multiple alignments of quality close to hand edited ones and outperforms several other methods. We also introduce a method of SCFG constraints that dramatically reduces the required computer resources needed to effectively use SCFGs on large problems such as SSU rRNA. Without such constraints, the required computer resources are infeasible for most computers. This work has applications to fields such as phylogenetic tree construction.
14196251
Unsupervised 3D object recognition and reconstruction in unordered datasets
This paper presents a system for fully automatic recognition and reconstruction of 3D objects in image databases. We pose the object recognition problem as one of finding consistent matches between all images, subject to the constraint that the images were taken from a perspective camera. We assume that the objects or scenes are rigid. For each image, we associate a camera matrix, which is parameterised by rotation, translation and focal length. We use invariant local features to find matches between all images, and the RANSAC algorithm to find those that are consistent with the fundamental matrix. Objects are recognised as subsets of matching images. We then solve for the structure and motion of each object, using a sparse bundle adjustment algorithm. Our results demonstrate that it is possible to recognise and reconstruct 3D objects from an unordered image database with no user input at all.
17357523
Visualization: expanding scientific and engineering research opportunities
The use of scientific visualization to represent the solutions obtained in computational science and engineering is discussed. The short- and long-term needs of those who use visualization tools and those who create them are addressed. For the user a three-tiered model environment is beginning to emerge that categorizes visualization systems by such factors as power, cost, and software support. Workstations with access to supercomputers are also required. The need to educate the scientific and engineering research communities about the available equipment is also discussed, and the available software and hardware are described.<<ETX>>
37211415
A Hypertext for Literate Programming
In this paper we describe a hypertext presentation for the WEB system for literate programming. The requirements for an environment for modern literate programming are analyzed and the WEB hypertext system is proposed. Different types of windows for displaying text, indices and graphical representations are discussed. All semantic links and operators using them are analyzed. The proposed architecture of the WEB hypertext system includes a general purpose relational database management system. Mapping between hypertext queries and relational database queries is provided. The system allows the user to define new hypertext operations by providing the corresponding SQL queries for the underlying relational database. The described system can be easily extended by many other types of queries and applications.