38046402
A semi-direct approach to structure from motion
Reconstructing three-dimensional structure and motion is often decomposed into two steps: point feature correspondence and three-dimensional reconstruction. This separation often causes gross errors since correspondence relies on the brightness constancy constraint that is local in space and time. Therefore, we advocate the necessity to integrate visual information not only in time (i.e. across different views), but also in space, by matching regions-rather than points-using explicit photometric deformation models. We present an algorithm that integrates 2D region tracking and 3D motion estimation into a closed loop based on an explicit geometric and photometric model, while detecting and rejecting outlier regions that do not fit the model. Our algorithm is recursive and suitable for real-time implementation. Our experiments show that it far exceeds the accuracy and robustness of point feature-based SFM algorithms.
2282922
Estimation of 3D Surface Shape and Smooth Radiance from 2D Images: A Level Set Approach
We cast the problem of shape reconstruction of a scene as the global region segmentation of a collection of calibrated images. We assume that the scene is composed of a number of smooth surfaces and a background, both of which support smooth Lambertian radiance functions. We formulate the problem in a variational framework, where the solution (both the shape and radiance of the scene) is a minimizer of a global cost functional which combines a geometric prior on shape, a smoothness prior on radiance and a data fitness score. We estimate the shape and radiance via an alternating minimization: The radiance is computed as the solutions of partial differential equations defined on the surface and the background. The shape is estimated using a gradient descent flow, which is implemented using the level set method. Our algorithm works for scenes with smooth radiances as well as fine homogeneous textures, which are known challenges to traditional stereo algorithms based on local correspondence.
14241332
Visual tracking in the presence of motion blur
We consider the problem of visual tracking of regions of interest in a sequence of motion blurred images. Traditional methods couple tracking with deblurring in order to correctly account for the effects of motion blur. Such coupling is usually appropriate, but computationally wasteful when visual tracking is the lone objective. Instead of deblurring images, we propose to match regions by blurring them. The matching score for two image regions is governed by a cost function that only involves the region deformation parameters and two motion blur vectors. We present an efficient algorithm to minimize the proposed cost function and demonstrate it on sequences of real blurred images.
6346856
Real-Time Feature Tracking and Outlier Rejection with Changes in Illumination
We develop an efficient algorithm to track point features supported by image patches undergoing aflne deformations and changes in illumination. The algorithm is based on a combined model of geonietty and photometry that is used to track features as well as to detect outliers in a hypothesis testing framework. The algorithm runs in real time on a personal computer, and is available to the public.
2927787
Real-time virtual object insertion
We present a system to insert virtual objects into real image sequences in real time. The system consists of offthe- shelf hardware (a camera connected to a Pentium PC) and software to (a) automatically select and track region features despite changes in illumination, (b) estimate threedimensional position and orientation of surface patches relative to an inertial reference frame despite individual pointfeatures appearing and disappearing, (c) insert a texturemapped virtual object into the scene so as to make it appear to be part of the scene and moving with it. This is all done in real time. The multi-thread C++ code, which is readily interfaced with a frame grabber as well as Matlab for development, will be made available to the public at the demonstration.
15692724
Region-Based Segmentation on Evolving Surfaces with Application to 3D Reconstruction of Shape and Piecewise Constant Radiance
We consider the problem of estimating the shape and radiance of a scene from a calibrated set of images under the assumption that the scene is Lambertian and its radiance is piecewise constant. We model the radiance segmentation explicitly using smooth curves on the surface that bound regions of constant radiance. We pose the scene reconstruction problem in a variational framework, where the unknowns are the surface, the radiance values and the segmenting curves. We propose an iterative procedure to minimize a global cost functional that combines geometric priors on both the surface and the curves with a data fitness score. We carry out the numerical implementation in the level set framework.
32436469
Special issue on scalable web services and architecture
With the rapid growth of the Internet, web services are becoming an increasingly important class of driving applications for scalable computer systems. Due to the popularity of many Internet applications, the load on Internet servers (web servers, proxy/caching servers, firewalls, etc.) is rapidly increasing. The next generation of Web services should support a very high rate of requests with varying needs imposing a big challenge for the networking infrastructure and the server environments. Since the network bandwidth increases faster than the server capacity, the server could be the next bottleneck of Web services. The efficient execution of Web applications will need to employ parallelism into the Application layer, and overall, into the Web server: (1) Intra-server parallelism, i.e. parallel execution of the web server tasks (e.g. a task or a thread for each HTTP request); (2) Inter-server parallelism, i.e. concurrent execution of different web servers. Cluster computing, a cost-effective technique to connect many small-scale computers to build a large-scale parallel computer, is the first step to build more powerful, interconnected, high performance computing systems. In particular, clusterbased distributed servers are being deployed by more and more popular web sites for scalable and highly available services. Major areas of research and development today include: caching and dynamic content delivering of scalable web servers to security solutions of computational grid. Topic areas covered include, scalability of distributed servers; web server traffic characterization; scheduling and load balancing on distributed servers; distributed server monitoring, fault tolerance, and management; caching, data replication, and concurrency control; security mechanism and policies for distributed servers. This special issue contains seven papers that deal with many of those issues. The purpose was to report both theoretical and practical solutions to some of the problems, and to identify new areas of research. In the first paper, A New Consistency Algorithm for Dynamic Documents in Content Distribution Networks, Fei develops a new strategy to maintain data consistency and integrity of dynamic documents in Content Distribution Networks (CDN). Compared to traditional propagation and invalidation approach to maintain the consistency of data at replicas with the original copy at the server, author proposed a hybrid approach that
8032236
First story detection in TDT is hard
✁✄✂✆☎✞✝✠✟☛✡✌☞✞✟☛✟✎✍✑✏✓✒✄✔✕✒ ✗✖✘✝✠✡✚✙✛✂✜✍ ✢✂✜✡✜✍✢✝✠✒✤✣✦✥✗✣✧☎★✔✪✩✫✥✬✡✮✭✯✝✠✣✘✰★✱✲✔ ✳✙✴✔✶✵ ✂✌✷✸✂✜✣✯✍☛✹✻✺✘✥✗✟☛✂ ✼☎✽✝✾✣❀✿❁✒✬✩✢❂❃✥✬✍✢✝✠✒✤✣❄✒✗✩✢✰✤✥✗✣✞✝✾❅✌✥✬✍✢✝✠✒✤✣ ❆✍✫✥✗✟☛✭✯✟✌❇❈✍☛✩✫✥✗✡✫✭❀✝✠✣✞✰ ✥✗✣✘☎ ❊❉✞✩✢✟ ❋✍❃✟❋✍✢✒✗✩☛●★☎❀✂✜✍✢✂✌✡✜✍✢✝✠✒✤✣■❍❏✁ ❑✂✆✟☛▲✘✒✼✏ ▼✍✢▲✧✥ ◆✍ ❖✏P▲✘✂✜✣◗✥❘❉✞✩✢✟❋✍ ✟❋✍✢✒✗✩☛●❙☎✞✂✜✍✢✂✌✡✮✍✢✝✾✒✗✣ ❚✟❋●❀✟❋✍✢✂✌❂❯✝✠✟❱✺✘✥✗✟☛✂✼☎❲☞✘✖❳✒✗✣✚✍☛✩✫✥✗✡✫✭❀✝✠✣✞✰❨✍✢✂✌✡✫▲✘✣✞✒✤❩❬✹ ✒✤✰✬●❪❭✤✏✓✂✶✡✌✥✗✣❖✂✜❫❀✖❳✂✌✡✮✍ ❴✍✢▲✘✥✬✍❴✖❳✂✜✩☛✿❵✒✗✩✢❂❃✥✗✣✞✡✌✂✳✏P✝✠❩✠❩✧✺❳✂❛✖❳✒❪✒✗✩✼❍❴✔✳▲✘✥✬✍ ✖✞✩✢✂✌☎✞✝✠✡✜✍✢✝✠✒✤✣❜✝✠✟✕✡✌✒✗✣✘✟☛✝✠✟❋✍✢✂✌✣❪✍ ❝✏P✝❬✍✢▲✎✥✬✡✜✍✢☞✧✥✬❩❪✖❳✂✜✩☛✿❁✒✬✩✢❂❃✥✗✣✞✡✌✂✓✝✠✣❜✔✳✙✴✔ ✂✌✷✗✥✗❩✠☞✧✥◆✍✢✝✠✒✤✣✘✟✌❍❞✁❑✂
✍✢▲✘✂✜✣❢✟☛▲✞✒◆✏ ❣✍✢▲✘✥✬✍❛✍✢✒✎✥✗✡✫▲✘✝✠✂✌✷✸✂
▲✘✝✠✰✤▲❀✹✑❤❪☞✘✥✗❩✠✝❬✍✑● ❉✘✩✢✟❋✍✪✟❋✍✢✒✗✩☛●✴☎✞✂✜✍✢✂✌✡✮✍✢✝✾✒✗✣✪❭◆✍☛✩✫✥✗✡✫✭✯✝✠✣✘✰❛✂✜✐❥✂✌✡✮✍✢✝✾✷✤✂✌✣✘✂✌✟☛✟✪❂✎☞✞✟❋✍✕✝✠❂❦✖✞✩✢✒◆✷✸✂ ✍✢✒✛✥
☎✞✂✌✰✬✩✢✂✌✂✓✍✢▲✘✥✬✍❧✂✜❫❀✖❳✂✜✩✢✝✠✂✌✣✞✡✌✂✳✟☛☞✞✰✤✰✤✂✜✟❋✍✢✟❴✝✠✟❧☞✞✣✘❩✠✝✠✭✸✂✌❩❬●❪❍✪✁❑✂✳✡✌✒✗✣✞✹ ✡✌❩✠☞✧☎❀✂✶✍✢▲✘✥✬✍✓✂✜✐❥✂✌✡✜✍✢✝✠✷✸✂✶❉✘✩✢✟❋✍✳✟❋✍✢✒✬✩☛●❃☎✞✂✮✍✢✂✌✡✜✍✢✝✠✒✤✣❨✝✠✟✓✂✌✝❬✍✢▲✘✂✮✩❛✝✠❂❦✖❳✒✤✟❋✹ ✟☛✝✠✺✘❩✠✂✴✒✗✩P✩✢✂✼❤❪☞✞✝✠✩✢✂✜✟✶✟☛☞✞✺✘✟❋✍✫✥✬✣✯✍✢✝✾✥✬❩✾❩❬●✆☎✞✝❬✐❥✂✜✩✢✂✌✣❪✍✶✥✬✖✘✖✞✩✢✒✤✥✗✡✫▲✘✂✌✟✌❍
15922848
The Stanford Microarray Database
The Stanford Microarray Database (SMD) stores raw and normalized data from microarray experiments, and provides web interfaces for researchers to retrieve, analyze and visualize their data. The two immediate goals for SMD are to serve as a storage site for microarray data from ongoing research at Stanford University, and to facilitate the public dissemination of that data once published, or released by the researcher. Of paramount importance is the connection of microarray data with the biological data that pertains to the DNA deposited on the microarray (genes, clones etc.). SMD makes use of many public resources to connect expression information to the relevant biology, including SGD [Ball,C.A., Dolinski,K., Dwight,S.S., Harris,M.A., Issel-Tarver,L., Kasarskis,A., Scafe,C.R., Sherlock,G., Binkley,G., Jin,H. et al. (2000) Nucleic Acids Res., 28, 77-80], YPD and WormPD [Costanzo,M.C., Hogan,J.D., Cusick,M.E., Davis,B.P., Fancher,A.M., Hodges,P.E., Kondu,P., Lengieza,C., Lew-Smith,J.E., Lingner,C. et al. (2000) Nucleic Acids Res., 28, 73-76], Unigene [Wheeler,D.L., Chappey,C., Lash,A.E., Leipe,D.D., Madden,T.L., Schuler,G.D., Tatusova,T.A. and Rapp,B.A. (2000) Nucleic Acids Res., 28, 10-14], dbEST [Boguski,M.S., Lowe,T.M. and Tolstoshev,C.M. (1993) Nature Genet., 4, 332-333] and SWISS-PROT [Bairoch,A. and Apweiler,R. (2000) Nucleic Acids Res., 28, 45-48] and can be accessed at http://genome-www.stanford.edu/microarray.