Spatial resolution

Annual sequences of the first reprocessed albedo, bidirectional reflectance distribution function (BRDF), and nadir BRDF-adjusted surface reflectance (NBAR) products are being evaluated. BRDF model parameters (or weights) are used to compute black sky albedo at local solar noon and white sky albedo and to compute surface reflectance at a common nadir geometry. In addition to these standard resolution albedo, BRDF, and NBAR products, which are provided in the integerized sinusoidal grid projection, the BRDF parameters, black sky albedos (at local solar noon), and white sky albedos are now also being operationally produced in a global geographic projection known as the Climate Modeling Grid (CMG). These are currently available at a 0.25 degree spatial resolution, although there is community interest in a 0.05 degree resolution. In addition to the operational CMGs, coarser 0.5 degree and 1 degree resolution versions of the reprocessed albedo data have also been produced for the ISLSCP-II initiative. The global distribution of these albedos (as they vary throughout the year) are presented, as well as discussions of the most recent evaluations of the quality of the standard products.

The spatial resolution of numerical weather prediction and climate models is generally determined by their grid spacing (∆x) or spectral truncation and the numerical implementation of dynamical core and model parametrisations. For example features of the scale 2∆x and 3∆x are smoothed to avoid numerical instabilities (e.g., aliasing effects) and parameterisations in connection to advection, pressure gradient force, and subgrid-scale diffusion can only be well represented at dimensions of at least four times the grid spacing. Some parametrisations, however, generate energy at the grid-spacing scale. These multiple effects on the effective resolution of models are investigated in this study for three high resolution regional climate models (RCMs) in dependence of their grid spacing.

A radio heliograph operating in the frequency range of 1200–1700 MHz is planned by INPE, Brazil, for investigations of time evolution of active regions, which will lead to better understanding of the physics of the flares energy release and particle acceleration, in order to suggest better criteria for the prediction of solar flares, Coronal Mass Ejections (CME), and solar terrestrial relations, such as geomagnetic storms and radio blackouts. In the first phase, the Brazilian Decimetric Array (BDA) will be a T shaped array 256 m by 144 m, consisting of 26 parabolic dish antennas of 4 m diameter. This array will produce full disk images of the sun with a spatial resolution of 3 by 5 arc minutes at 1420 MHz with a time resolution of 100 ms and sensitivity of ∼ 10 Jy. In the second phase, in addition to the compact T array there will be 6 more 7 m diameter antennas on an East-West baseline of 2560 m to obtain higher spatial resolution and better sensitivity. Thus, finally this radioheliograph will have wide field of view and couple of arcsec spatial resolution and high time resolution (100 ms).

Fiber tracking (FT) and quantification algorithms are approximations of reality due to limited spatial resolution, model assumptions, user-defined parameter settings, and physical imaging artifacts resulting from diffusion sequences. Until now, correctness, plausibility, ...

A wide variety of imaging applications exist for 1K x 1K midwave infrared (MWIR) imagers and Nova's Variable Acuity Superpixel Imager (VASTM) technology1,2 has now progressed to this image format. This paper will demonstrate a variety of imagery from MWIR cameras using this large format "LVASI" device; the in-pixel processing used by the LVASI cameras represents the state-of-the-art for image size, total field of view, high frame rates, low data bandwidths and real-time spatial reprogrammability of focal plane arrays (FPAs). Using these devices, imaging systems may now be implemented that permit the operator to "zoom in" to regions of interest with very high spatial resolution, while covering the remainder of the total field of view (TFOV) at conventional resolutions. The bandwidth compression attainable using these sensors helps to make possible systems that can transmit their high resolution imagery through wireless interconnected networks. We present recent infrared image data that highlight numerous applications including missile detection/tracking, search/rescue and remote surveillance applications.

Purpose The aim of this study was to improve the uniformity of the axial spatial resolution and sensitivity in pinhole single-photon emission computed tomography (SPECT) and to extend the axial field of view, by using a dedicated three-pinhole collimator. Methods A rectangular tungsten plate with three pinhole apertures of 1.5 mm diameter was designed to image a cylindrical field of view of 55 mm diameter and 160 mm axial length using a clinical gamma camera. To evaluate the non-uniformity of spatial resolution and noise, a multiple-disk phantom was built. The phantom was filled with Tc-99m, and data were acquired using a circular orbit and reconstructed with a dedicated iterative reconstruction algorithm. The axial spatial resolution together with the noise was measured in each disk. These measurements were compared to a single-pinhole system using an identical acquisition geometry and reconstruction. Results At the central slice, a spatial resolution of 2.7 mm was observed for both the three-pinhole and single-pinhole geometries. At 17.5 mm from the central slice, the axial spatial resolution deteriorated to 10.3 mm when using a single pinhole, while the spatial resolution remained 2.7 mm for the three-pinhole system. In the central slice, 19% noise was observed for both geometries. At 31.5 mm from this central slice, the noise remained 19% for the three-pinhole geometry, while it increased to 32% using a single pinhole. Conclusion The presented three-pinhole collimator improves the uniformity of the axial spatial resolution and sensitivity in pinhole SPECT and consequently extends the axial field of view, a requirement for whole-body small-animal imaging.

This article describes a fiber-optic interrogation device based on the pulsed time-of-flight technique. The apparatus is capable of measuring time delays between wideband reflectors, such as connectors, along a fiber path with a precision of about 280 fs (rms value) and a spatial resolution of about 3 ns (0.30 m) in a measurement time of 25 ms. Potential application areas include measuring integral strain and its derivatives such as cracks, deflections, and displacements, particularly in large civil engineering and composite structures. The operation and basic blocks of the measurement system are presented in detail together with measurement results obtained in laboratory and field conditions. It is shown that by using a fiber loop sensor with a reference fiber, it is possible to achieve a strain precision below 1 microstrain and a measurement frequency of 4 Hz. System performance proved adequate for the study of both static and dynamic phenomena in a bridge deck.

Touch (or tactile) sensors are gaining renewed interest as the level of sophistication in the application of minimum invasive surgery and humanoid robots increases. The spatial resolution of current large-area (greater than 1 cm 2 ) tactile sensor lags by more than an order of magnitude compared with the human finger. By using metal and semiconducting nanoparticles, a ∼100-nm-thick, large-area thin-film device is self-assembled such that the change in current density through the film and the electroluminescent light intensity are linearly proportional to the local stress. A stress image is obtained by pressing a copper grid and a United States 1-cent coin on the device and focusing the resulting electroluminescent light directly on the charge-coupled device. Both the lateral and height resolution of texture are comparable to the human finger at similar stress levels of ∼10 kilopascals.

10 High-Dynamic Range Imaging for Dynamic Scenes Celine Loscos and Katrien Jacobs 10.1 Introduction................................................................ 259 10.2 High-Dynamic Range Images: Definition.................................... 261 10.3 HDR Image Creation from Multiple Exposures........ ...