Abstract
ZY-3 has been acquiring high quality imagery since its launch in 2012 and its tri-stereo (three-view or three-line-array) imagery has become one of the top choices for extracting DSM (Digital Surface Model) products in China over the past few years. The ZY-3 tri-stereo sensors offer users the ability to capture imagery over large regions including an entire territory of a country, such as China, resulting in a large volume of ZY-3 tri-stereo scenes which require timely (e.g., near real time) processing, something that is not currently possible using traditional photogrammetry workstations. This paper presents a high performance computing solution which can efficiently and automatically extract DSM products from ZY-3 tri-stereo imagery. The high performance computing solution leverages certain parallel computing technologies to accelerate computation within an individual scene and then deploys a distributed computing technology to increase the overall data throughput in a robust and efficient manner. By taking advantage of the inherent efficiencies within the high performance computing environment, the DSM extraction process can exploit all combinations offered from a set of tri-stereo images (forward-backword, forward-nadir and backword-nadir). The DSM results merged from all of the potential combinations can minimize blunders (e.g., incorrect matches) and also offer the ability to remove potential occlusions which may exist in a single stereo pair, resulting in improved accuracy and quality versus those that are not merged. Accelerated performance is inherent within each of the individual steps of the DSM extraction workflow, including the collection of ground control points and tie points, image bundle adjustment, the creation of epipolar images, and computing elevations. Preliminary experiments over a large area in China have proven that the high performance computing system can generate high quality and accurate DSM products in a rapid manner.
Highlights
Among a large number of Earth Observation (EO) using ZY-3 tri-stereo imagery
One of the predominant features that makes ZY-3 so popular is that it offers the potential to extract high quality DSM/DEM solutions were sought from the high performance (Digital Elevation Model) products from its tri-stereo imagery (Li, 2012)
In the manual workstation system, each scene was processed (e.g., GCPs are collected manually) sequentially and the total processing time was calculated from the time for the single scene multiplied by the number of images; in the high performance system, the time was the actual time elapsing for processing all scenes since multiple scenes can be processed simultaneously
Summary
Among a large number (more than 50) of Earth Observation (EO) using ZY-3 tri-stereo imagery. In order to provide full coverage satellites (Guo, 2012) (Xu, et al, 2014) (Deng, et al, 2014a) of the entire territory of China using ZY-3 imagery, more than launched by China from 2004 to 2016, ZY-3 is considered as one 30,000 scenes must be acquired and processed. Processing this of the most successful Chinese satellites (Li, 2012). ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume III-1, 2016 XXIII ISPRS Congress, 12–19 July 2016, Prague, Czech Republic perspective could simultaneously execute computation from different tasks and increase the overall data throughput in a limited time (WikiPedia, 2015e) (Deng, et al, 2014a)
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