Australian SKA Pathfinder: A High-Dynamic Range Wide-Field of View Survey Telescope

2009 ◽  
Vol 97 (8) ◽  
pp. 1507-1521 ◽  
Author(s):  
David R. DeBoer ◽  
Russell G. Gough ◽  
John D. Bunton ◽  
Tim J. Cornwell ◽  
Ron J. Beresford ◽  
...  
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Field Of View ◽  
Wide Field ◽  
Wide Field Of View ◽  
High Dynamic

scholarly journals SunCET: The Sun Coronal Ejection Tracker Concept

2021 ◽  
Author(s):  
James Paul Mason ◽  
Phillip C Chamberlin ◽  
Daniel Seaton ◽  
Joan Burkepile ◽  
Robin Colaninno ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Extreme Ultraviolet ◽  
High Dynamic Range ◽  
Field Of View ◽  
Integration Time ◽  
Wide Field ◽  
The Sun ◽  
Wide Field Of View ◽  
High Dynamic ◽  
Short Integration Time

The Sun Coronal Ejection Tracker (SunCET) is an extreme ultraviolet imager and spectrograph instrument concept for tracking coronal mass ejections through the region where they experience the majority of their acceration: the difficult-to-observe middle corona. It contains a wide field of view (0--4~\Rs) imager and a 1~\AA\ spectral-resolution-irradiance spectrograph spanning 170--340~\AA. It leverages new detector technology to read out different areas of the detector with different integration times, resulting in what we call ``simultaneous high dynamic range", as opposed to the traditional high dynamic range camera technique of subsequent full-frame images that are then combined in post-processing. This allows us to image the bright solar disk with short integration time, the middle corona with a long integration time, and the spectra with their own, independent integration time. Thus, SunCET does not require the use of an opaque or filtered occulter. SunCET is also compact --- $\sim$15 $\times$ 15 $\times$ 10~cm in volume --- making it an ideal instrument for a CubeSat or a small, complimentary addition to a larger mission.

scholarly journals High-dynamic-range imaging for cloud segmentation

2018 ◽  
Vol 11 (4) ◽  
pp. 2041-2049 ◽  
Author(s):  
Soumyabrata Dev ◽  
Florian M. Savoy ◽  
Yee Hui Lee ◽  
Stefan Winkler
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Wide Field ◽  
Single Shot ◽  
Generation Process ◽  
Image Generation ◽  
Large Dynamic Range ◽  
Exposure Fusion ◽  
Wide Field Of View ◽  
High Dynamic

Abstract. Sky–cloud images obtained from ground-based sky cameras are usually captured using a fisheye lens with a wide field of view. However, the sky exhibits a large dynamic range in terms of luminance, more than a conventional camera can capture. It is thus difficult to capture the details of an entire scene with a regular camera in a single shot. In most cases, the circumsolar region is overexposed, and the regions near the horizon are underexposed. This renders cloud segmentation for such images difficult. In this paper, we propose HDRCloudSeg – an effective method for cloud segmentation using high-dynamic-range (HDR) imaging based on multi-exposure fusion. We describe the HDR image generation process and release a new database to the community for benchmarking. Our proposed approach is the first using HDR radiance maps for cloud segmentation and achieves very good results.

scholarly journals High-Dynamic-Range Imaging for Cloud Segmentation

2017 ◽  
Author(s):  
Soumyabrata Dev ◽  
Florian M. Savoy ◽  
Yee Hui Lee ◽  
Stefan Winkler
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Wide Field ◽  
Single Shot ◽  
Generation Process ◽  
Large Dynamic Range ◽  
Exposure Fusion ◽  
Wide Field Of View ◽  
High Dynamic ◽  
Fish Eye

Abstract. Sky/cloud images obtained from ground-based sky-cameras are usually captured using a fish-eye lens with a wide field of view. However, the sky exhibits a large dynamic range in terms of luminance, more than a conventional camera can capture. It is thus difficult to capture the details of an entire scene with a regular camera in a single shot. In most cases, the circumsolar region is over-exposed, and the regions near the horizon are under-exposed. This renders cloud segmentation for such images difficult. In this paper, we propose HDRSeg – an effective method for cloud segmentation using High-Dynamic-Range (HDR) imaging based on multi-exposure fusion. We describe the HDR generation process and release a new database to the community for benchmarking. Our proposed approach is the first using HDR images for cloud segmentation and achieves very good results.

scholarly journals Non-Intrusive Luminance Mapping via High Dynamic Range Imaging and 3-D Reconstruction

2021 ◽  
Vol 2042 (1) ◽  
pp. 012113
Author(s):  
Michael Kim ◽  
Athanasios Tzempelikos
Keyword(s):  
Dynamic Range ◽  
Low Cost ◽  
High Dynamic Range ◽  
Field Of View ◽  
High Dynamic Range Imaging ◽  
3D Space ◽  
Short Video ◽  
High Dynamic ◽  
Daylighting Control ◽  
Good Agreement

Abstract Continuous luminance monitoring is challenging because high-dynamic-range cameras are expensive, they need programming, and are intrusive when placed near the occupants’ field-of-view. A new semi-automated and non-intrusive framework is presented for monitoring occupant-perceived luminance using a low-cost camera sensor and Structure-from- Motion (SfM)-Multiview Stereo (MVS) photogrammetry pipeline. Using a short video and a few photos from the occupant position, the 3D space geometry is automatically reconstructed. Retrieved 3D context enables the back-projection of the camera-captured luminance distribution into 3D spaces that are in turn re-projected to occupant-FOVs. The framework was tested and validated in a testbed office. The re-projected luminance field showed with good agreement with luminance measured at the occupant position. The new method can be used for non-intrusive luminance monitoring integrated with daylighting control applications.

scholarly journals Adaptive-scale wide-field reconstruction for radio synthesis imaging

2020 ◽  
Vol 640 ◽  
pp. A80
Author(s):  
L. Zhang ◽  
L. G. Mi ◽  
M. Zhang ◽  
X. Liu ◽  
C. L. He
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Wide Field ◽  
Observation Data ◽  
Field Observations ◽  
High Dynamic Range Imaging ◽  
Range Imaging ◽  
Low Frequencies ◽  
Very Large Array ◽  
High Dynamic

Sky curvature and non-coplanar effects, caused by low frequencies, long baselines, or small apertures in wide field-of-view instruments such as the Square Kilometre Array (SKA), significantly limit the imaging performance of an interferometric array. High dynamic range imaging essentially requires both an excellent sky model and the correction of imaging factors such as non-coplanar effects. New CLEAN deconvolution with adaptive-scale modeling already has the ability to construct significantly better narrow-band sky models. However, the application of wide-field observations based on modern arrays has not yet been jointly explored. We present a new wide-field imager that can model the sky on an adaptive-scale basis, and the sky curvature and the effects of non-coplanar observations with the w-projection method. The degradation caused by the dirty beam due to incomplete spatial frequency sampling is eliminated during sky model construction by our new method, while the w-projection mainly removes distortion of sources far from the image phase center. Applying our imager to simulated SKA data and the real observation data of the Karl G. Jansky Very Large Array (an SKA pathfinder) suggested that our imager can handle the effects of wide-field observations well and can reconstruct more accurate images. This provides a route for high dynamic range imaging of SKA wide-field observations, which is an important step forward in the development of the SKA imaging pipeline.

scholarly journals A Multi-Frequency VLBI Polarization Study of the CSS Quasar 3C 309.1

1998 ◽  
Vol 164 ◽  
pp. 105-106
Author(s):  
Scott E. Aaron ◽  
John F.C. Wardle ◽  
David H. Roberts
Keyword(s):  
Radio Source ◽  
Dynamic Range ◽  
Ambient Medium ◽  
High Dynamic Range ◽  
Field Of View ◽  
Large Field ◽  
General Properties ◽  
Polarization Study ◽  
Rotation Measure ◽  
High Dynamic

AbstractWe discuss the rotation measure properties of the CSS quasar 3C 309.1, determined from high dynamic range, large field of view VLBA images at several frequencies between 1.4 and 15 GHz. We consider the general properties of the ambient medium by considering the structure of the Faraday screen across various parts of the radio source.

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