Aaron Heller

Framework for robust 3D change detection

We present an application of our framework for 3-D object- centered change detection to combined satellite and aerial imagery. In this framework, geometry is compared to geometry, allowing us to compare image sets with different acquisition conditions and even different sensors. By working in this framework, we do not encounter the restrictions and short-comings of conventional image-based change detection, which requires that the images being compared have similar acquisition geometry, photometry, scene illumination, and so forth. The contributions of our framework are: (1) using a geometric basis for change detection, allowing image sets acquired under different conditions to be compared; (2) explicit modeling of image geometry to be able to numerically characterize significant and insignificant change. The contributions of this paper are: (1) the algorithms are embedded in an integrated cartographic modeling and image processing system, which can ingest and make use of a variety of government and commercial imagery and geospatial data products; (2) experimentation with a variety of imagery and scene content. Modifications to the algorithm specific to their use with satellite imagery are discussed and the results from several experiments with both aerial and satellite images urban domains are described and analyzed.

In situ evaluation of surround sound system performance

Surround sound systems are produced with the intention of reproducing the spatial aspects of sound, such as localization and envelopment. As part of his work on Ambisonics, Gerzon developed two metrics, the velocity and energy localization vectors, which are intended to predict the localization performance of a system. These are used during the design process to optimize the decoder that supplies signals to the loudspeaker array. At best, subjective listening tests are conducted on the finished system, but no objective assessments of the spatial qualities are made to verify that the realized performance correlates the predictions. In the present work, binaural recordings were made of a 3-D 24-loudspeaker installation at Stanford’s Bing Studio. Test signals were used to acquire the binaural impulse response of each loudspeaker in the array and of Ambisonic reproduction using the loudspeaker array. The measurements were repeated at several locations within the hall. Subsequent analysis calculated the ITDs a...

Coordinate systems and transformations for 3D modeling: the unifying concept in the RADIUS common development environment

The RADIUS Common Development Environment pulls together many diverse functions into an integrated whole. The main goal of the environment is to provide a system to do interactive modeling of 3-dimensional scenes from multiple images, as well as, providing an infrastructure to support the research in and implementation of image understanding-based algorithms for this and other tasks. The RCDE contains facilities for: CAD-system-like 3D modeling; image processing; electronic-light-table image viewing and exploitation; frame and non-frame camera photogrammetry; and photo realistic rendering. The major achievement of the system is the high level of integration and interoperability between and among these facilities. The key realization that enables this is that every entity represented in the RCDE has an associated local coordinate system. This includes cartographic and cultural features, images and sub-images, text annotations, graphical user interface elements, photogrammetric conjugate points and even the earth itself. These entities are tied together through a flexible and efficient network of coordinate transformations. This allows each type of data to be represented, manipulated, and displayed in the most convenient and precise form, without sacrificing functionality or generality, in addition to enabling the fusion of different types of geometric data. In this paper, we explain the coordinate system representations and transformation facilities in the RCDE and outline some of the rationale and strategies behind the current design and implementation. Also included are examples drawn from its use in the government sponsored RADIUS program.