3,948 research outputs found
LOCALIS: Locally-adaptive Line Simplification for GPU-based Geographic Vector Data Visualization
Visualization of large vector line data is a core task in geographic and
cartographic systems. Vector maps are often displayed at different cartographic
generalization levels, traditionally by using several discrete levels-of-detail
(LODs). This limits the generalization levels to a fixed and predefined set of
LODs, and generally does not support smooth LOD transitions. However, fast GPUs
and novel line rendering techniques can be exploited to integrate dynamic
vector map LOD management into GPU-based algorithms for locally-adaptive line
simplification and real-time rendering. We propose a new technique that
interactively visualizes large line vector datasets at variable LODs. It is
based on the Douglas-Peucker line simplification principle, generating an
exhaustive set of line segments whose specific subsets represent the lines at
any variable LOD. At run time, an appropriate and view-dependent error metric
supports screen-space adaptive LOD levels and the display of the correct subset
of line segments accordingly. Our implementation shows that we can simplify and
display large line datasets interactively. We can successfully apply line style
patterns, dynamic LOD selection lenses, and anti-aliasing techniques to our
line rendering
SAM-2 ground-truth plan: Correlative measurements for the Stratospheric Aerosol Measurement-2 (SAM 2) sensor on the Nimbus G satellite
The SAM-2 will fly aboard the Nimbus-G satellite for launch in the fall of 1978 and measure stratospheric vertical profiles of aerosol extinction in high latitude bands. The plan gives details of the location and times for the simultaneous satellite/correlative measurements for the nominal launch time, the rationale and choice of the correlative sensors, their characteristics and expected accuracies, and the conversion of their data to extinction profiles. The SAM-2 expected instrument performance and data inversion results are presented. Various atmospheric models representative of polar stratospheric aerosols are used in the SAM-2 and correlative sensor analyses
CELLULAR REQUIREMENTS FOR THE PRIMARY IN VITRO ANTIBODY RESPONSE TO DNP-FICOLL
The cellular requirements for the primary in vitro IgM and IgG response to dinitrophenyl-substituted Ficoll were examined. Neither thymus-derived lymphocytes nor macrophage-rich splenic adherent cells were required for anti-DNP antibody synthesis. DNP-Ficoll is therefore tentatively classified as a "thymic-independent" antigen
The Hubble Space Telescope Treasury Program on the Orion Nebula Cluster
The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster
has used 104 orbits of HST time to image the Great Orion Nebula region with the
Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2)
and the Near Infrared Camera and Multi Object Spectrograph (NICMOS) instruments
in 11 filters ranging from the U-band to the H-band equivalent of HST. The
program has been intended to perform the definitive study of the stellar
component of the ONC at visible wavelengths, addressing key questions like the
cluster IMF, age spread, mass accretion, binarity and cirumstellar disk
evolution. The scanning pattern allowed to cover a contiguous field of
approximately 600 square arcminutes with both ACS and WFPC2, with a typical
exposure time of approximately 11 minutes per ACS filter, corresponding to a
point source depth AB(F435W) = 25.8 and AB(F775W)=25.2 with 0.2 magnitudes of
photometric error. We describe the observations, data reduction and data
products, including images, source catalogs and tools for quick look preview.
In particular, we provide ACS photometry for 3399 stars, most of them detected
at multiple epochs, WFPC2 photometry for 1643 stars, 1021 of them detected in
the U-band, and NICMOS JH photometry for 2116 stars. We summarize the early
science results that have been presented in a number of papers. The final set
of images and the photometric catalogs are publicly available through the
archive as High Level Science Products at the STScI Multimission Archive hosted
by the Space Telescope Science Institute.Comment: Accepted for publication on the Astrophysical Journal Supplement
Series, March 27, 201
- …