9,615 research outputs found
Locating the LCROSS Impact Craters
The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted
a spent Centaur rocket stage into a permanently shadowed region near the lunar
south pole. The Sheperding Spacecraft (SSC) separated \sim9 hours before impact
and performed a small braking maneuver in order to observe the Centaur impact
plume, looking for evidence of water and other volatiles, before impacting
itself. This paper describes the registration of imagery of the LCROSS impact
region from the mid- and near-infrared cameras onboard the SSC, as well as from
the Goldstone radar. We compare the Centaur impact features, positively
identified in the first two, and with a consistent feature in the third, which
are interpreted as a 20 m diameter crater surrounded by a 160 m diameter ejecta
region. The images are registered to Lunar Reconnaisance Orbiter (LRO)
topographical data which allows determination of the impact location. This
location is compared with the impact location derived from ground-based
tracking and propagation of the spacecraft's trajectory and with locations
derived from two hybrid imagery/trajectory methods. The four methods give a
weighted average Centaur impact location of -84.6796\circ, -48.7093\circ, with
a 1{\sigma} un- certainty of 115 m along latitude, and 44 m along longitude,
just 146 m from the target impact site. Meanwhile, the trajectory-derived SSC
impact location is -84.719\circ, -49.61\circ, with a 1{\sigma} uncertainty of 3
m along the Earth vector and 75 m orthogonal to that, 766 m from the target
location and 2.803 km south-west of the Centaur impact. We also detail the
Centaur impact angle and SSC instrument pointing errors. Six high-level LCROSS
mission requirements are shown to be met by wide margins. We hope that these
results facilitate further analyses of the LCROSS experiment data and follow-up
observations of the impact region.Comment: Accepted for publication in Space Science Review. 24 pages, 9 figure
A Comprehensive Survey of Deep Learning in Remote Sensing: Theories, Tools and Challenges for the Community
In recent years, deep learning (DL), a re-branding of neural networks (NNs),
has risen to the top in numerous areas, namely computer vision (CV), speech
recognition, natural language processing, etc. Whereas remote sensing (RS)
possesses a number of unique challenges, primarily related to sensors and
applications, inevitably RS draws from many of the same theories as CV; e.g.,
statistics, fusion, and machine learning, to name a few. This means that the RS
community should be aware of, if not at the leading edge of, of advancements
like DL. Herein, we provide the most comprehensive survey of state-of-the-art
RS DL research. We also review recent new developments in the DL field that can
be used in DL for RS. Namely, we focus on theories, tools and challenges for
the RS community. Specifically, we focus on unsolved challenges and
opportunities as it relates to (i) inadequate data sets, (ii)
human-understandable solutions for modelling physical phenomena, (iii) Big
Data, (iv) non-traditional heterogeneous data sources, (v) DL architectures and
learning algorithms for spectral, spatial and temporal data, (vi) transfer
learning, (vii) an improved theoretical understanding of DL systems, (viii)
high barriers to entry, and (ix) training and optimizing the DL.Comment: 64 pages, 411 references. To appear in Journal of Applied Remote
Sensin
Application of Generalized Partial Volume Estimation for Mutual Information based Registration of High Resolution SAR and Optical Imagery
Mutual information (MI) has proven its effectiveness for automated multimodal image registration for numerous remote sensing applications like image fusion. We analyze MI performance with respect to joint histogram bin size and the employed joint histogramming technique. The affect of generalized partial volume estimation (GPVE) utilizing B-spline kernels with different histogram bin sizes on MI performance has been thoroughly explored for registration of high resolution SAR (TerraSAR-X) and optical (IKONOS-2) satellite images. Our experiments highlight possibility of an inconsistent MI behavior with different joint histogram bin size which gets reduced with an increase in order of B-spline kernel employed in GPVE. In general, bin size reduction and/or increasing B-spline order have a smoothing affect on MI surfaces and even the lowest order B-spline with a suitable histogram bin size can achieve same pixel level accuracy as achieved by the higher order kernels more consistently
Deep learning in remote sensing: a review
Standing at the paradigm shift towards data-intensive science, machine
learning techniques are becoming increasingly important. In particular, as a
major breakthrough in the field, deep learning has proven as an extremely
powerful tool in many fields. Shall we embrace deep learning as the key to all?
Or, should we resist a 'black-box' solution? There are controversial opinions
in the remote sensing community. In this article, we analyze the challenges of
using deep learning for remote sensing data analysis, review the recent
advances, and provide resources to make deep learning in remote sensing
ridiculously simple to start with. More importantly, we advocate remote sensing
scientists to bring their expertise into deep learning, and use it as an
implicit general model to tackle unprecedented large-scale influential
challenges, such as climate change and urbanization.Comment: Accepted for publication IEEE Geoscience and Remote Sensing Magazin
Supervised / unsupervised change detection
The aim of this deliverable is to provide an overview of the state of the art in change detection techniques and a critique of what could be programmed to derive SENSUM products. It is the product of the collaboration between UCAM and EUCENTRE. The document includes as a necessary requirement a discussion about a proposed technique for co-registration. Since change detection techniques require an assessment of a series of images and the basic process involves comparing and contrasting the similarities and differences to essentially spot changes, co-registration is the first step. This ensures that the user is comparing like for like. The developed programs would then be used on remotely sensed images for applications in vulnerability assessment and post-disaster recovery assessment and monitoring. One key criterion is to develop semi-automated and automated techniques.
A series of available techniques are presented along with the advantages and disadvantages of each method. The descriptions of the implemented methods are included in the deliverable D2.7 ”Software Package SW2.3”.
In reviewing the available change detection techniques, the focus was on ways to exploit medium resolution imagery such as Landsat due to its free-to-use license and since there is a rich historical coverage arising from this satellite series.
Regarding the change detection techniques with high resolution images, this was also examined and a recovery specific change detection index is discussed in the report
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