Locally Non-rigid Registration for Mobile HDR Photography

Image registration for stack-based HDR photography is challenging. If not properly accounted for, camera motion and scene changes result in artifacts in the composite image. Unfortunately, existing methods to address this problem are either accurate, but too slow for mobile devices, or fast, but prone to failing. We propose a method that fills this void: our approach is extremely fast---under 700ms on a commercial tablet for a pair of 5MP images---and prevents the artifacts that arise from insufficient registration quality

Color correction for mobile panorama imaging

This paper presents a simple and efficient color and lumi-nance compensation approach for image sequences for con-structing panoramic images on mobile devices. In this ap-proach, constant compensation coefficients for adjacent im-ages are computed from the corresponding pixels in the over-lapping areas of the adjacent images in the linearized RGB color space. A global adjustment for all compensation coeffi-cients is performed so that the correction for each image is as small as possible. This can smooth color transition between adjacent images in the image sequence globally and reduce cumulative errors in the color correction process. The com-pensation coefficients, together with the global adjustment factor, are applied to correct color and luminance of source images in the image sequence before they are stitched into a panoramic image. Our algorithm is not sensitive to the quality of spatial registration since it does not need exact pixel correspon-dences between the overlapped images. The computation of compensation coefficients for each adjacent image takes the gamma correction factor into account, producing better re-sults. Running the method separately on the three channels matches the color balance that may not match due to auto-white-balancing algorithm. A global adjustment for the compensation coefficients minimizes color transitions and re-duces cumulative errors. The approach is integrated into a sequential image stitching procedure and implemented in a mobile panorama system, good results have been obtained for both indoor and outdoor scenes

Acquisition and Visualization of Colored 3D Objects

This paper presents a complete system for scanning the geometry and surface color of a 3D object and for displaying realistic images of the object from arbitrary viewpoints. A stereo system with active light produces several views of dense range and color data. The data is registered and a surface that approximates the data is constructed. The surface estimate can be fairly coarse, as the appearance of fine detail is recreated by view-dependent texturing of the surface using color images

Surface reconstruction and display from range and color data

Thesis (Ph. D.)--University of Washington, 1997This dissertation addresses the problem of scanning both the color and geometry of real objects and displaying realistic images of the scanned objects from arbitrary viewpoints. We present a complete system that uses a stereo camera system with active lighting to scan the object surface geometry and color as visible from one point of view. Scans expressed in sensor coordinates are registered into a single object-centered coordinate system by aligning both the color and geometry where the scans overlap. The range data are integrated into a surface model using a robust hierarchical space carving method. The fit of the resulting approximate mesh to data is improved and the mesh structure is simplified using mesh optimization methods. Two methods are developed to do view-dependent display of the reconstructed surfaces. The first method integrates the geometric data into a single model as described above and projects the color data from the input images onto the surface. The second method models the scans separately as textured triangle meshes, and integrates the data during display by rendering several partial models from the current viewpoint and combining the images pixel by pixel

Multiview Registration for Large Data Sets

In this paper we present a multiview registration method for aligning range data. We first align scans pairwise with each other and use the pairwise alignments as constraints that the multiview step enforces while evenly diffusing the pairwise registration errors. This approach is especially suitable for registering large data sets, since using constraints from pairwise alignments does not require loading the entire data set into memory to perform the alignment. The alignment method is efficient, and it is less likely to get stuck into a local minimum than previous methods, and can be used in conjunction with any pairwise method based on aligning overlapping surface sections

TRIBORS: A Triplet-Based Object Recognition System

this paper is called TRIBORS (Triplet-Based Object Recognition System). Like PREMIO, TRIBORS uses synthesized images to create probability models for matching. The main motivation for this research was to try out the ideas of the PREMIO system, provide a Prune the Probability Model Obtain real images Match objects using the Probability Model and pose estimator (Eqs. 1&2) Match image and model lines using pose, wireframe and Eq. 3 Create new Probability Model and prune it Create synthetic image

New APIs for Mobile Graphics

Progress in mobile graphics technology during the last five years has been swift, and it has followed a similar path as on PCs: early proprietary software engines running on integer hardware paved the way to standards that provide a roadmap for graphics hardware acceleration. In this overview we cover five recent standards for 3D and 2D vector graphics for mobile devices. OpenGL ES is a low-level API for 3D graphics, meant for applications written in C or C++. M3G (JSR 184) is a high-level 3D API for mobile Java that can be implemented on top of OpenGL ES. Collada is a content interchange format and API that allows combining digital content creation tools and exporting the results to different run-time systems, including OpenGL ES and M3G. Two new 2D vector graphics APIs reflect the relations of OpenGL ES and M3G: OpenVG is a low-level API for C/C++ that can be used as a building block for a high-level mobile Java API JSR 226

Transition and learning strategies

From a researcher to a manager

Fast Rendering of Subdivision Surfaces

Subdivision surfaces provide a curved surface representation that is useful in a number of applications, including modeling surfaces of arbitrary topological type, fitting scattered data, and geometric compression and automatic level-of-detail generation using wavelets. Subdivision surfaces also provide an attractive representation for fast rendering, since they can directly represent complex surfaces of arbitrary topology. We present a method for subdivision surface triangulation that is fast, uses minimum memory, and is simpler in structure than a naive rendering method based on direct subdivision. These features make the algorithm amenable to implementation on both general purpose CPUs and dedicated geometry engine processors, allowing high rendering performance on appropriately equipped graphics hardware