991 research outputs found
Exploiting 2D Floorplan for Building-scale Panorama RGBD Alignment
This paper presents a novel algorithm that utilizes a 2D floorplan to align
panorama RGBD scans. While effective panorama RGBD alignment techniques exist,
such a system requires extremely dense RGBD image sampling. Our approach can
significantly reduce the number of necessary scans with the aid of a floorplan
image. We formulate a novel Markov Random Field inference problem as a scan
placement over the floorplan, as opposed to the conventional scan-to-scan
alignment. The technical contributions lie in multi-modal image correspondence
cues (between scans and schematic floorplan) as well as a novel coverage
potential avoiding an inherent stacking bias. The proposed approach has been
evaluated on five challenging large indoor spaces. To the best of our
knowledge, we present the first effective system that utilizes a 2D floorplan
image for building-scale 3D pointcloud alignment. The source code and the data
will be shared with the community to further enhance indoor mapping research
Properties of Sequential Chromospheric Brightenings and Associated Flare Ribbons
We report on the physical properties of solar sequential chromospheric
brightenings (SCBs) observed in conjunction with moderate-sized chromospheric
flares with associated CMEs. To characterize these ephemeral events, we
developed automated procedures to identify and track subsections (kernels) of
solar flares and associated SCBs using high resolution H-alpha images.
Following the algorithmic identification and a statistical analysis, we compare
and find the following: SCBs are distinctly different from flare kernels in
their temporal characteristics of intensity, Doppler structure, duration, and
location properties. We demonstrate that flare ribbons are themselves made up
of subsections exhibiting differing characteristics. Flare kernels are measured
to have a mean propagation speed of 0.2 km/s and a maximum speed of 2.3 km/s
over a mean distance of 5 x 10^3 km. Within the studied population of SCBs,
different classes of characteristics are observed with coincident negative,
positive, or both negative and positive Doppler shifts of a few km/s. The
appearance of SCBs precede peak flare intensity by ~12 minutes and decay ~1
hour later. They are also found to propagate laterally away from flare center
in clusters at 41 km/s or 89 km/s. Given SCBs distinctive nature compared to
flares, we suggest a different physical mechanism relating to their origin than
the associated flare. We present a heuristic model of the origin of SCBs.Comment: 24 pages, 17 figure
An effective, low-cost measure of semantic relatedness obtained from Wikipedia links
This paper describes a new technique for obtaining measures of semantic relatedness. Like other recent approaches, it uses Wikipedia to provide structured world knowledge about the terms of interest. Out approach is unique in that it does so using the hyperlink structure of Wikipedia rather than its category hierarchy or textual content. Evaluation with manually defined measures of semantic relatedness reveals this to be an effective compromise between the ease of computation of the former approach and the accuracy of the latter
Using the R Package crlmm for Genotyping and Copy Number Estimation
Genotyping platforms such as Affymetrix can be used to assess genotype-phenotype as well as copy number-phenotype associations at millions of markers. While genotyping algorithms are largely concordant when assessed on HapMap samples, tools to assess copy number changes are more variable and often discordant. One explanation for the discordance is that copy number estimates are susceptible to systematic differences between groups of samples that were processed at different times or by different labs. Analysis algorithms that do not adjust for batch effects are prone to spurious measures of association. The R package crlmm implements a multilevel model that adjusts for batch effects and provides allele-specific estimates of copy number. This paper illustrates a workflow for the estimation of allele-specific copy number and integration of the marker-level estimates with complimentary Bioconductor software for inferring regions of copy number gain or loss. All analyses are performed in the statistical environment R.
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