Aircraft and Ship Velocity Determination in Sentinel-2 Multispectral Images

Abstract

The Sentinel-2 satellites in the Copernicus program provide high resolution multispectral images, which are recorded with temporal offsets up to 2.6 s. Moving aircrafts and ships are therefore observed at different positions due to the multispectral band offsets, from which velocities can be determined. We describe an algorithm for detecting aircrafts and ships, and determining their speed, heading, position, length, etc. Aircraft velocities are also affected by the parallax effect and jet streams, and we show how the altitude and the jet stream speed can be determined from the geometry of the aircraft and/or contrail heading. Ship speeds are more difficult to determine as wakes affect the average ship positions differently in the various multispectral bands, and more advanced corrections methods are shown to improve the velocity determination.

Ship-Iceberg Classification in SAR and Multispectral Satellite Images with Neural Networks

“…For each object, a small region of 75 × 75 pixels is extracted around the central object coordinate, such that it covers the object extent including wakes. The same region is now extracted for the 4 high-resolution bands m = 1, 2, 3, 4 (blue, green, red, and near-infrared) with spatial resolution 10 m. The other 6 bands with 20 m and the 3 bands with 60 m pixel resolution are not used in this analysis because they have less spatial information (see however [25]). For convenience, we combine the red and near-infrared bands m = 3, 4, to have the 3 color images as is commonly used for image recognition in neural nets.…”

“…Smearing is useful when backscatter/reflections are varying over land. Aircrafts are easily removed as they move fast and the temporal delay during acquisition separates the multispectral bands [25]. An aircraft appears twice separated in red and NIR both with high redness.…”

Remote Sensing in Vessel Detection and Navigation

“…Heiselberg [ 13 ] demonstrated for the first time that the time delay between recording the 13 images for the Sentinel-2 multispectral imager can be exploited to determine ship and aircraft velocities from space. The movement in the image during recording is substantial for aircrafts but only just measurable for the much slower ships.…”

Measuring Economic Activity From Space: A Case Study Using Flying Airplanes and COVID-19

“…Besides, Landsat-8's repeat cycle of 16 days [32] hinders the ability to use temporal data to cope with these difficulties. Heiselberg [33] and Liu et al [30] utilized images captured by the Sentinel-2 satellites for the same job. These satellites' multispectral instrument design makes them observe the earth's surface at different times in each spectral band [34].…”