11,724 research outputs found
Learning Sparse High Dimensional Filters: Image Filtering, Dense CRFs and Bilateral Neural Networks
Bilateral filters have wide spread use due to their edge-preserving
properties. The common use case is to manually choose a parametric filter type,
usually a Gaussian filter. In this paper, we will generalize the
parametrization and in particular derive a gradient descent algorithm so the
filter parameters can be learned from data. This derivation allows to learn
high dimensional linear filters that operate in sparsely populated feature
spaces. We build on the permutohedral lattice construction for efficient
filtering. The ability to learn more general forms of high-dimensional filters
can be used in several diverse applications. First, we demonstrate the use in
applications where single filter applications are desired for runtime reasons.
Further, we show how this algorithm can be used to learn the pairwise
potentials in densely connected conditional random fields and apply these to
different image segmentation tasks. Finally, we introduce layers of bilateral
filters in CNNs and propose bilateral neural networks for the use of
high-dimensional sparse data. This view provides new ways to encode model
structure into network architectures. A diverse set of experiments empirically
validates the usage of general forms of filters
Navigation and guidance requirements for commercial VTOL operations
The NASA Langley Research Center (LaRC) has undertaken a research program to develop the navigation, guidance, control, and flight management technology base needed by Government and industry in establishing systems design concepts and operating procedures for VTOL short-haul transportation systems in the 1980s time period. The VALT (VTOL Automatic Landing Technology) Program encompasses the investigation of operating systems and piloting techniques associated with VTOL operations under all-weather conditions from downtown vertiports; the definition of terminal air traffic and airspace requirements; and the development of avionics including navigation, guidance, controls, and displays for automated takeoff, cruise, and landing operations. The program includes requirements analyses, design studies, systems development, ground simulation, and flight validation efforts
GPS-denied multi-agent localization and terrain classification for autonomous parafoil systems
Guided airdrop parafoil systems depend on GPS for localization and landing. In some scenarios, GPS may be unreliable (jammed, spoofed, or disabled), or unavailable (indoor, or extraterrestrial environments). In the context of guided parafoils, landing locations for each system must be pre-programmed manually with global coordinates, which may be inaccurate or outdated, and offer no in-flight adaptability. Parafoil systems in particular have constrained motion, communication, and on-board computation and storage capabilities, and must operate in harsh conditions. These constraints necessitate a comprehensive approach to address the fundamental limitations of these systems when GPS cannot be used reliably. A novel and minimalist approach to visual navigation and multi-agent communication using semantic machine learning classification and geometric constraints is introduced. This approach enables localization and landing site identification for multiple communicating parafoil systems deployed in GPS-denied environments
HAT-P-17b,c: A Transiting, Eccentric, Hot Saturn and a Long-period, Cold Jupiter
We report the discovery of HAT-P-17b,c, a multi-planet system with an inner
transiting planet in a short-period, eccentric orbit and an outer planet in a
4.8 yr, nearly circular orbit. The inner planet, HAT-P-17b, transits the bright
V = 10.54 early K dwarf star GSC 2717-00417, with an orbital period P =
10.338523 +/- 0.000009 d, orbital eccentricity e = 0.346 +/- 0.007, transit
epoch T_c = 2454801.16945 +/- 0.00020, and transit duration 0.1691 +/- 0.0009
d. HAT-P-17b has a mass of 0.530 +/- 0.018 M_J and radius of 1.010 +/- 0.029
R_J yielding a mean density of 0.64 +/- 0.05 g cm^-3. This planet has a
relatively low equilibrium temperature in the range 780-927 K, making it an
attractive target for follow-up spectroscopic studies. The outer planet,
HAT-P-17c, has a significantly longer orbital period P_2 = 1797^+58_-89 d and a
minimum mass m_2 sin i_2 = 1.4^+1.1_-0.4 M_J. The orbital inclination of
HAT-P-17c is unknown as transits have not been observed and may not be present.
The host star has a mass of 0.86 +/- 0.04 M_Sun, radius of 0.84 +/- 0.02,
effective temperature 5246 +/- 80 K, and metallicity [Fe/H] = 0.00 +/- 0.08.
HAT-P-17 is the second multi-planet system detected from ground-based transit
surveys.Comment: Submitted to ApJ, 13 pages, 6 figures, 6 table
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