Aircraft-based stereographic reconstruction of 3-D cloud geometry
<p>This work describes a method to retrieve the location and geometry of clouds using RGB images from a video camera on an aircraft and data from the aircraft's navigation system. Opposed to ordinary stereo methods for which two cameras with fixed relative position at a certain distance a...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-02-01
|
| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/12/1155/2019/amt-12-1155-2019.pdf |
| Summary: | <p>This work describes a method to retrieve the location and geometry of clouds
using RGB images from a video camera on an aircraft and data from the
aircraft's navigation system. Opposed to ordinary stereo methods for which
two cameras with fixed relative position at a certain distance are used to
match images taken at the exact same moment, this method uses only a single
camera and the aircraft's movement to provide the needed parallax. Advantages
of this approach include a relatively simple installation on a (research)
aircraft and the possibility to use different image offsets that are even
larger than the size of the aircraft. Detrimental effects are the evolution
of observed clouds during the time offset between two images as well as the
background wind. However we will show that some wind information can also be
recovered and subsequently used for the physics-based filtering of outliers.
Our method allows the derivation of cloud top geometry which can be used,
e.g., to provide location and distance information for other passive cloud
remote sensing products. In addition it can also improve retrieval methods by
providing cloud geometry information useful for the correction of 3-D
illumination effects. We show that this method works as intended through
comparison to data from a simultaneously operated lidar system. The stereo
method provides lower heights than the lidar method; the median difference is
<span class="inline-formula">126</span> m. This behavior is expected as the lidar method has a lower detection
limit (leading to greater cloud top heights for the downward view), while the
stereo method also retrieves data points on cloud sides and lower cloud
layers (leading to lower cloud heights). Systematic errors across the
measurement swath are less than <span class="inline-formula">50</span> m.</p> |
|---|---|
| ISSN: | 1867-1381 1867-8548 |