Stereophotogrammetry of Oceanic Clouds

2014 ◽  
Vol 31 (7) ◽  
pp. 1482-1501 ◽  
Author(s):  
Rusen Öktem ◽  
Prabhat ◽  
James Lee ◽  
Aaron Thomas ◽  
Paquita Zuidema ◽  
...  
Keyword(s):  
Camera Calibration ◽  
Cloud Base ◽  
Biscayne Bay ◽  
Digital Cameras ◽  
Image Pair ◽  
Single Image ◽  
Calibration Technique ◽  
Launch Site ◽  
Stereo Cameras ◽  
Stereo Reconstruction

This study extends ground-based stereophotogrammetry of clouds to oceanic settings, where there are often none of the landmarks used in traditional camera calibration. This paper introduces a zero-landmark calibration technique and tests it with two off-the-shelf digital cameras situated about 1 km apart facing Biscayne Bay in Miami, Florida. The precision of the stereo reconstruction is studied theoretically, and the accuracy of the reconstructions is validated against lidar and radiosondes. The stereo cameras are able to accurately reconstruct a histogram of cloud-base heights from a single-image pair, a task that requires tens of minutes of observation from a cloud lidar. The stereo cameras are also able to accurately reconstruct horizontal winds in cloud layers with a temporal resolution in the range of 30 s to 5 min, compared to once every 12 h for a typical radiosonde launch site.

scholarly journals Observing Clouds in 4D with Multiview Stereophotogrammetry

2018 ◽  
Vol 99 (12) ◽  
pp. 2575-2586 ◽  
Author(s):  
David M. Romps ◽  
Ruşen Öktem
Keyword(s):  
Great Plains ◽  
Climate Models ◽  
Life Cycles ◽  
Digital Cameras ◽  
Southern Great Plains ◽  
Stereo Cameras ◽  
Weather And Climate ◽  
Stereo Reconstruction ◽  
Shallow Clouds ◽  
Atmospheric Radiation Measurement

AbstractNewly installed stereo cameras ringing the Southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site in Oklahoma are providing a 4D gridded view of shallow clouds. Six digital cameras have been installed in pairs at a distance of 6 km from the site and with a spacing of 500 m between cameras in a pair. These pairs of cameras provide stereoscopic views of shallow clouds from all sides; when these data are combined, they allow for a complete stereo reconstruction. The result—the Clouds Optically Gridded by Stereo (COGS) product—is a 4D grid of cloudiness covering a 6 km × 6 km × 6 km cube at a spatial resolution of 50 m and a temporal resolution of 20 s. This provides a unique set of data on the sizes, lifetimes, and life cycles of shallow clouds. This type of information is critical for developing cloud macrophysical schemes for the next generation of weather and climate models.

scholarly journals Cloud Photogrammetry with Dense Stereo for Fisheye Cameras

2016 ◽  
Author(s):  
Christoph Beekmans ◽  
Johannes Schneider ◽  
Thomas Läbe ◽  
Cyrill Stachniss ◽  
Clemens Simmer
Keyword(s):  
Large Field ◽  
Cloud Base ◽  
Strong Wind ◽  
Real World Data ◽  
First Case ◽  
Dense Matching ◽  
Cloud Dynamics ◽  
Stereo Reconstruction ◽  
3D Information ◽  
Fisheye Lenses

Abstract. In this paper, we present our approach for dense 3D cloud reconstruction using two hemispheric sky imagers with fisheye lenses in a stereo setup. Fisheye lenses follow a different projection function than classical pinhole-type cameras, which provide a large field of view with a single image, but also renders the computation of dense 3D information more complicated, such that we cannot rely entirely on standard implementations for dense 3D stereo reconstruction. In this work, we examine the epipolar rectification model, which allows the use of dense matching algorithms designed for classical perspective cameras to search for disparity information at every pixel. Together with an appropriate camera calibration, which includes internal camera geometry and global position and orientation of the stereo camera pair, we can use the disparity information for dense 3D stereo reconstruction of the a cloud and thus estimate its shape. From the obtained 3D shapes, cloud dynamics, size, motion, type and spacing can be derived and used e.g. for radiation closure under cloudy conditions. We implemented and evaluated the proposed approach using real world data and present two case studies. In the first case, we validate the quality and accuracy of the method by comparing the stereo reconstruction of a stratocumulus layer with the reflectivity observations measured by a cloud radar and the cloud base height estimated from a Lidar-ceilometer. The second case analyzes a rapid cumulus convection in the presence of strong wind shear.

Camera Calibration Technique Based on Active Vision

2010 ◽  
Vol 30 (5) ◽  
pp. 1297-1303 ◽  
Author(s):  
朱嘉 Zhu Jia ◽  
李醒飞 Li Xingfei ◽  
徐颖欣 Xu Yingxin
Keyword(s):  
Camera Calibration ◽  
Active Vision ◽  
Calibration Technique

scholarly journals Cloud photogrammetry with dense stereo for fisheye cameras

2016 ◽  
Vol 16 (22) ◽  
pp. 14231-14248 ◽  
Author(s):  
Christoph Beekmans ◽  
Johannes Schneider ◽  
Thomas Läbe ◽  
Martin Lennefer ◽  
Cyrill Stachniss ◽  
...  
Keyword(s):  
Stereo Matching ◽  
Geometric Constraints ◽  
Large Field ◽  
Cloud Base ◽  
Strong Wind ◽  
Real World Data ◽  
First Case ◽  
Novel Approach ◽  
Stereo Reconstruction ◽  
Fisheye Lenses

Abstract. We present a novel approach for dense 3-D cloud reconstruction above an area of 10 × 10 km2 using two hemispheric sky imagers with fisheye lenses in a stereo setup. We examine an epipolar rectification model designed for fisheye cameras, which allows the use of efficient out-of-the-box dense matching algorithms designed for classical pinhole-type cameras to search for correspondence information at every pixel. The resulting dense point cloud allows to recover a detailed and more complete cloud morphology compared to previous approaches that employed sparse feature-based stereo or assumed geometric constraints on the cloud field. Our approach is very efficient and can be fully automated. From the obtained 3-D shapes, cloud dynamics, size, motion, type and spacing can be derived, and used for radiation closure under cloudy conditions, for example. Fisheye lenses follow a different projection function than classical pinhole-type cameras and provide a large field of view with a single image. However, the computation of dense 3-D information is more complicated and standard implementations for dense 3-D stereo reconstruction cannot be easily applied. Together with an appropriate camera calibration, which includes internal camera geometry, global position and orientation of the stereo camera pair, we use the correspondence information from the stereo matching for dense 3-D stereo reconstruction of clouds located around the cameras. We implement and evaluate the proposed approach using real world data and present two case studies. In the first case, we validate the quality and accuracy of the method by comparing the stereo reconstruction of a stratocumulus layer with reflectivity observations measured by a cloud radar and the cloud-base height estimated from a Lidar-ceilometer. The second case analyzes a rapid cumulus evolution in the presence of strong wind shear.

Camera calibration technique with planar scenes

2003 ◽  
Author(s):  
Yongjun Zhang ◽  
Zuxun Zhang ◽  
Jianqing Zhang
Keyword(s):  
Camera Calibration ◽  
Calibration Technique

scholarly journals A Perceptual Measure for Deep Single Image Camera Calibration

2018 ◽  
Author(s):  
Yannick Hold-Geoffroy ◽  
Kalyan Sunkavalli ◽  
Jonathan Eisenmann ◽  
Matt Fisher ◽  
Emiliano Gambaretto ◽  
...  
Keyword(s):  
Camera Calibration ◽  
Single Image ◽  
Image Camera ◽  
Perceptual Measure
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