Search results for " RENDERING"
showing 10 items of 82 documents
Landsat and Local Land Surface Temperatures in a Heterogeneous Terrain Compared to MODIS Values
2016
Land Surface Temperature (LST) as provided by remote sensing onboard satellites is a key parameter for a number of applications in Earth System studies, such as numerical modelling or regional estimation of surface energy and water fluxes. In the case of Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra or Aqua, pixels have resolutions near 1 km 2 , LST values being an average of the real subpixel variability of LST, which can be significant for heterogeneous terrain. Here, we use Landsat 7 LST decametre-scale fields to evaluate the temporal and spatial variability at the kilometre scale and compare the resulting average values to those provided by MODIS for the same obser…
Enhancing the retrieval of stream surface temperature from Landsat data
2019
International audience; Thermal images of water bodies often show a radiance gradient perpendicular to the banks. This effect is frequently due to mixed land and water thermal pixels. In the case of the Landsat images, radiance mixing can also affect pure water pixels due the cubic convolution resampling of the native thermal measurements. Some authors recommended a general-purpose margin of two thermal pixels to the banks or a minimum river width of three pixels, to avoid near bank effects in water temperature retrievals. Given the relatively course spatial resolution of satellite thermal sensors, the three pixel margin severely restricts their application to temperature mapping in many ri…
Registration of Surfaces Minimizing Error Propagation for a One-Shot Multi-Slit Hand-Held Scanner
2008
We propose an algorithm for the on-line automatic registration of multiple 3D surfaces acquired in a sequence by a new hand-held laser scanner. The laser emitter is coupled with an optical lens that spreads the light forming 19 parallel slits that are projected to the scene and acquired with subpixel accuracy by a camera. Splines are used to interpolate the acquired profiles to increase the sample of points and Delaunay triangulation is used to obtain the normal vectors at every point. A point-to-plane pair-wise registration method is proposed to align the surfaces in pairs while they are acquired, conforming paths and eventually cycles that are minimized once detected. The algorithm is spe…
Visualization of Simulated Arrhythmias due to Gap Junctions
2018
New computational models are able to simulate details of cardiac cell networks. Their results allow a better understanding of the functionality of the heart and suggest possible actions to reduce non-fatal premature beats that can give rise to serious diseases. We developed a user-friendly interface to organize Neuron simulations and to present in real-time a three-dimensional representation of the electrical activity due to the gap junctions which interconnect the cells inside cardiac tissues. All physiological parameters were set according to real experimental observations and compared against different types of arrhythmias, retrieved from the Physionet Data Base.
Two-dimensional and three-dimensional sonography of conjoined twins.
2002
Purpose The aim of this study was to evaluate and compare the diagnostic capabilities of 2-dimensional (2D) and 3-dimensional (3D) sonography for the study of conjoined twins. Methods Four pregnant women with an initial 2D sonographic diagnosis of conjoined twins were examined with color Doppler sonography, 3D multiplanar sonography, and orthogonal plane imaging and 3D surface rendering. Results All 4 cases of conjoined twins were initially diagnosed with either transvaginal or transabdominal 2D sonography. 3D sonography afforded more realistic views and demonstrated more clearly the linking areas and surface anomalies, but 2D and color Doppler sonography provided more definitive and specif…
Autostereoscopic Three-Dimensional Neuronavigation to the Sella: Technical Note.
2017
Background A drawback of conventional neuronavigation is the necessity of focusing on two-dimensional images in 3 planes at the same time to determine one's position in the operating field. A solution would be to merge the images into a single three-dimensional (3D) image that mirrors the actual anatomy. The introduction of holographic glassless 3D monitors paved the way to 3D navigation. We present our experience with 3D neuronavigation as exemplified by navigation to and within the sella. Methods Operative planning was conducted with a navigation system using cranial computed tomography and magnetic resonance imaging. The image data sets were processed by the prototype Clariti 3D system t…
Digital Mosaic Frameworks - an overview
2007
Art often provides valuable hints for technological innovations especially in the field of Image Processing and Computer Graphics. In this paper we survey in a unified framework several methods to transform raster input images into good quality mosaics. For each of the major different approaches in literature the paper reports a short description and a discussion of the most relevant issues. To complete the survey comparisons among the different techniques both in terms of visual quality and computational complexity are provided.
Fotografia e progetto
2008
Sentinel-3/FLEX Biophysical Product Confidence Using Sentinel-2 Land-Cover Spatial Distributions
2021
The estimation of biophysical variables from remote sensing data raises important challenges in terms of the acquisition technology and its limitations. In this way, some vegetation parameters, such as chlorophyll fluorescence, require sensors with a high spectral resolution that constrains the spatial resolution while significantly increasing the subpixel land-cover heterogeneity. Precisely, this spatial variability often makes that rather different canopy structures are aggregated together, which eventually generates important deviations in the corresponding parameter quantification. In the context of the Copernicus program (and other related Earth Explorer missions), this article propose…
Mathematical Methods in Image Processing and Computer Vision
2016
Image processing and computer vision are growing research fields that take advantage of the increasing power or modern computers linked with sophisticated techniques coming from many fields of expertise and in particular from mathematics. We present an introduction to some problems in computer vision and image processing and to some mathematical techniques and concepts that are nowadays routinely used to approach them.