NASA Technical Reports Server (NTRS) 20130009414: Metric Learning to Enhance Hyperspectral Image Segmentation

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by  NASA Technical Reports Server (NTRS)

systems that are too large to be simu- spatial scales from the coarse-grain scale This work was done by Scott Johnson, Otis
lated with a discrete element approach, (DEM) to the bulk scale (SPH). The Walton, and Randolph Settgast of Grain-
PowderSim incorporates a continuum- DEM capability also supports clustering, flow Dynamics for Glenn Research Center.
based SPH module, which when consid- which allows it to capture a rich variety Further information is contained in a TSP
ering the addition of a calibrated, cohe- of shape detail. Advanced contact mod- (see page 1).
sive, constitutive model (Lunar Regolith els and charge spots capture many ef- Inquiries concerning rights for the commer-
Constitutive Model (LRCM)), is a novel fects of contact plasticity and hysteresis, cial use of this invention should be addressed
use of mesh-free methods. Because of roughness, adhesion, and electrostatic to NASA Glenn Research Center, Innovative
the discrete and continuum methods interaction of particles. The SPH capa- Partnerships Office, Attn: Steven Fedor, Mail
implemented in the same framework, bility for bulk material behavior uses the Stop 4–8, 21000 Brookpark Road, Cleve-
the software can capture dynamic partic- LRCM to capture the critical-state behav- land, Ohio 44135. Refer to LEW-18801-1.
ulate material behavior at a variety of ior of cohesive lunar regolith.
Multiple-Frame Detection of Subpixel Targets in Thermal
Image Sequences
This technique has applicability in fire detection, and tracking ships, ground vehicles, and aircraft.
NASA’s Jet Propulsion Laboratory, Pasadena, California
The new technology in this approach consecutive frames, and uses geometric face. The ground system, with possible
combines the subpixel detection infor- relationships to estimate a “homogra- human assistance, would determine the
mation from multiple frames of a se- phy” — a transformation mapping be- SIFT features’ geographic locations.
quence to achieve a more sensitive de- tween frames. Interest points generally During regular operations, the system
tection result, using only the correspond to regions of high informa- can query the database to find geo-
information found in the images them- tion or contrast. Previous work provides graphic locations of new observations.
selves. It is taken as a constraint that the a wide range of interest point detectors. Any preferred single- or multiple-chan-
method is automated, robust, and com- In this innovation, SIFT (Scale Invariant nel detection rule is applied independ-
putationally feasible for field networks Feature Transform) keypoints recovered ently in each frame with a very lenient
with constrained computation and data by a difference of Gaussians (DoG) op- threshold. Then, the algorithm matches
rates. This precludes simply download- erator applied at multiple scales are consecutive detections across potentially
ing a video stream for pixel-wise co-regis- used. A nearest-neighbor matching pro- large displacements, and associates
tration on the ground. It is also impor- cedure identifies candidate matches be- them into tracks, i.e., unique physical
tant that this method not require precise tween frames. The end result of this first events with a precise geographic loca-
knowledge of sensor position or direc- step is a list of candidate interest points tion, that may appear in multiple
tion, because such information is often and descriptors in each frame. frames. Finally, the system considers the
not available. It is also assumed that the An important benefit of SIFT detec- entire sequence history of each track to
scene in question is approximately pla- tion is that the system permits absolute make the final detection decision.
nar, which is appropriate for a high-alti- georeferencing based on image contents This work was done by David R. Thomp-
tude airborne or orbital view. alone. The SIFT features alone provide son of Caltech and Robert Kremens of
This approach tracks scene content to sufficient information to geolocate a hot Rochester Institute of Technology for NASA’s
estimate camera motion and finds geo- pixel. This suggests an initial characteri- Jet Propulsion Laboratory. Further informa-
metric relationships between the im- zation phase where the remote observer tion is contained in a TSP (see page 1).
ages. An initial stage identifies stable transmits high-contrast, SIFT descriptors NPO-48129
image features, or interest points, in along with images of the (fire-free) sur-
Metric Learning to Enhance Hyperspectral Image Segmentation
NASA’s Jet Propulsion Laboratory, Pasadena, California
Unsupervised hyperspectral image duce the number of effective spectra in performance of unsupervised hyper-
segmentation can reveal spatial trends an image, enabling analyses that would spectral image segmentation. The pro-
that show the physical structure of the otherwise be computationally prohibi- totype demonstrations attempt a su-
scene to an analyst. They highlight bor- tive. Specifically, using an over-segmen- perpixel segmentation in which the
ders and reveal areas of homogeneity tation of the image instead of individ- image is conservatively over-seg-
and change. Segmentations are inde- ual pixels can reduce noise and mented; that is, the single surface fea-
pendently helpful for object recogni- potentially improve the results of statis- tures may be split into multiple seg-
tion, and assist with automated produc- tical post-analysis. ments, but each individual segment, or
tion of symbolic maps. Additionally, a In this innovation, a metric learning superpixel, is ensured to have homog-
good segmentation can dramatically re- approach is presented to improve the enous mineralogy.
36 NASA Tech Briefs, January 2013
A segmentation strategy was tested Hyperspectral segmentation algo- Rayleigh quotient computed over la-
based on the “Felzenszwalb” algorithm rithms partition images into spectrally beled training data. Other distance met-
for its simplicity and computational ef- homogenous regions. However, the rics and segmentation strategies are pos-
ficiency. This approach represents the exact definition of homogeneity is de- sible, and can be substituted for these
hyperspectral image as an 8-connected pendent on the chosen similarity metric. choices in modular fashion as different
grid of pixels that can begin as inde- The segmentation algorithm is aug- applications demand.
pendent segments. Edges between mented with a task-specific distance met- This work was done by David R. Thomp-
nodes represent the distance between ric. Here, a Mahalanobis distance metric son and Rebecca Castano of Caltech, Brian
neighboring spectra, and each is is used, learned from training data. By Bue of Rice University, and Martha S.
weighted according to a measure of dis- leveraging a (small) set of labeled pixels Gilmore of Wesleyan University for NASA’s Jet
tance between pixels. The algorithm it- with known mineralogical interpreta- Propulsion Laboratory. For more information,
eratively joins neighboring pixels to- tions, the metric suppresses uninforma- contact [email protected].
gether into larger segments, and tive spectral content. Multiclass linear This software is available for commercial li-
describes each segment by the mini- discriminant analysis (LDA) is used to censing. Please contact Daniel Broderick of
mum spanning tree of edges that joins maximize the ratio of between-class vs. the California Institute of Technology at
all segments in the cluster. within-class separation, defined by the [email protected]. Refer to NPO-48092.
Basic Operational Robotics Instructional System
Lyndon B. Johnson Space Center, Houston, Texas
The Basic Operational Robotics In- combined with a multibody dynamics tion of each of these systems required
structional System (BORIS) is a six-de- model, moving-object contact model, some specialized training that distracted
gree-of-freedom rotational robotic ma- and X-Windows based graphical user in- students from the ideas and goals of the
nipulator system simulation used for terfaces, coordinated in the Trick Simu- basic robotics instruction.
training of fundamental robotics con- lation modeling environment. This work was done by Brian Keith Todd of
cepts, with in-line shoulder, offset The motivation for development of Johnson Space Center, James Fischer of Titan
elbow, and offset wrist. BORIS is used to BORIS was the need for a generic system Systems Corp., and Jane Falgout and John
provide generic robotics training to for basic robotics training. Before Schweers of L-3 Communications. For further
aerospace professionals including flight BORIS, introductory robotics training information, contact the JSC Innovation Part-
crews, flight controllers, and robotics was done with either the SRMS (Shuttle nerships Office at [phone]. MSC-
instructors. It uses forward kinematic Remote Manipulator System) or SSRMS 24850-1
and inverse kinematic algorithms to (Space Station Remote Manipulator Sys-
simulate joint and end-effector motion, tem) simulations. The unique construc-
NASA Tech Briefs, January 2013 37