28,332 research outputs found
Geometric calibration of Colour and Stereo Surface Imaging System of ESA's Trace Gas Orbiter
There are many geometric calibration methods for "standard" cameras. These
methods, however, cannot be used for the calibration of telescopes with large
focal lengths and complex off-axis optics. Moreover, specialized calibration
methods for the telescopes are scarce in literature. We describe the
calibration method that we developed for the Colour and Stereo Surface Imaging
System (CaSSIS) telescope, on board of the ExoMars Trace Gas Orbiter (TGO).
Although our method is described in the context of CaSSIS, with camera-specific
experiments, it is general and can be applied to other telescopes. We further
encourage re-use of the proposed method by making our calibration code and data
available on-line.Comment: Submitted to Advances in Space Researc
Fisheye Photogrammetry to Survey Narrow Spaces in Architecture and a Hypogea Environment
Nowadays, the increasing computation power of commercial grade processors has actively led to a vast spreading of image-based reconstruction software as well as its application in different disciplines. As a result, new frontiers regarding the use of photogrammetry in a vast range of investigation activities are being explored. This paper investigates the implementation of
fisheye lenses in non-classical survey activities along with the related problematics. Fisheye lenses are outstanding because of their large field of view.
This characteristic alone can be a game changer in reducing the amount of data required, thus speeding up the photogrammetric process when needed. Although they come at a cost, field of view (FOV), speed and manoeuvrability are key to the success of those optics as shown by two of the presented case studies: the survey of a very narrow spiral staircase located in the Duomo di Milano and the survey of a very narrow hypogea structure in Rome. A third case study, which deals with low-cost sensors, shows the metric evaluation of a commercial spherical camera equipped with fisheye lenses
AAO Starbugs: software control and associated algorithms
The Australian Astronomical Observatory's TAIPAN instrument deploys 150
Starbug robots to position optical fibres to accuracies of 0.3 arcsec, on a 32
cm glass field plate on the focal plane of the 1.2 m UK-Schmidt telescope. This
paper describes the software system developed to control and monitor the
Starbugs, with particular emphasis on the automated path-finding algorithms,
and the metrology software which keeps track of the position and motion of
individual Starbugs as they independently move in a crowded field. The software
employs a tiered approach to find a collision-free path for every Starbug, from
its current position to its target location. This consists of three
path-finding stages of increasing complexity and computational cost. For each
Starbug a path is attempted using a simple method. If unsuccessful,
subsequently more complex (and expensive) methods are tried until a valid path
is found or the target is flagged as unreachable.Comment: 10 pages, to be published in Proc. SPIE 9913, Software and
Cyberinfrastructure for Astronomy IV; 201
Forward Vehicle Collision Warning Based on Quick Camera Calibration
Forward Vehicle Collision Warning (FCW) is one of the most important
functions for autonomous vehicles. In this procedure, vehicle detection and
distance measurement are core components, requiring accurate localization and
estimation. In this paper, we propose a simple but efficient forward vehicle
collision warning framework by aggregating monocular distance measurement and
precise vehicle detection. In order to obtain forward vehicle distance, a quick
camera calibration method which only needs three physical points to calibrate
related camera parameters is utilized. As for the forward vehicle detection, a
multi-scale detection algorithm that regards the result of calibration as
distance priori is proposed to improve the precision. Intensive experiments are
conducted in our established real scene dataset and the results have
demonstrated the effectiveness of the proposed framework
Hybrid Focal Stereo Networks for Pattern Analysis in Homogeneous Scenes
In this paper we address the problem of multiple camera calibration in the
presence of a homogeneous scene, and without the possibility of employing
calibration object based methods. The proposed solution exploits salient
features present in a larger field of view, but instead of employing active
vision we replace the cameras with stereo rigs featuring a long focal analysis
camera, as well as a short focal registration camera. Thus, we are able to
propose an accurate solution which does not require intrinsic variation models
as in the case of zooming cameras. Moreover, the availability of the two views
simultaneously in each rig allows for pose re-estimation between rigs as often
as necessary. The algorithm has been successfully validated in an indoor
setting, as well as on a difficult scene featuring a highly dense pilgrim crowd
in Makkah.Comment: 13 pages, 6 figures, submitted to Machine Vision and Application
Photometric and Astrometric Calibration of the JWST Instrument Complement
In preparation for James Webb Space Telescope (JWST), a set of cross
calibration programs with HST and Spitzer for suitable primary photometric
standards and astrometric fields were developed. NICMOS/HST and IRAC/Spitzer
photometry observations of new solar analog standards in NGC 6791 and Melotte
66 were executed. These new photometric standards will provide ~ 5% photometric
precision at V~19 from the near-IR to the mid-IR wavelength range for efficient
on-orbit calibration and measuring of photometric stability of the JWST
complement. For the astrometric calibration, a field in the LMC has been
selected. This field falls within the JWST continuous viewing zone, within 5
degrees from the ecliptic poles, and has the stellar density necessary to
achieve accuracies better than 1 mas with HST/ACS. These independent
observations will play a key role in meeting the mission requirements and will
allow a fast commissioning of the observatory.Comment: 9 pages, 3 figures; to appear in The Future of Photometric,
spectrophotometric, and Polarimetric Standardization, ed. C. Sterken, AS
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