SAR Video products are only produced when the Dwell collection mode is utilized
SAR Video (VID)
SAR Video is similar to the CSI product in which the acquired SAR data is divided into multiple sub-apertures. However, in the case of SAR Video, they are not used to create composite images. Instead, each discrete sub-aperture is used as a frame of a video.
Video is very useful in applications where moving objects need to be analyzed. By simple inspection and analysis of a video, it is possible to infer the general direction and speed of moving objects such as vessels and vehicles. SAR Video is also effective for detecting objects hidden in the forest area as well as human-made objects as these tend to give bright reflections and show as glint when playing a video.
Container format and metadata
The formats of the VID product are MPEG4 and GIF. Additionally, a GeoTIFF format is produced where each of the video frames is available as a separate band to facilitate frame by frame analysis in any image exploitation tools. The user can measure and track changes and moving objects between frames by stepping through the different bands of the image. ICEYE is able to produce SAR Video products (VID) only for certain types of collection characteristics such as Dwell. In the case of Dwell, each video is made of 25 frames (Note 1). Important metadata for each of each of the video frames is available in the GeoTIFF. GeoTIFF metadata can be accessed by multiple methods including:
- Using the gdal library and running the command
gdalinfo filename.tif(for example:
- Using the the open source application QGIS by selecting Raster → Miscellaneous → Raster information → Run
Key VID GeoTIFF Metadata
||Duration of SAR data collection for each video frame.||List of float64||seconds|
||Timestamp at the center of each video frame. Number of seconds since the beginning of the SAR collection||List of float64||seconds|
||Satellite position at the center of each video frame||List of float64 triplets||ECEF coordinates|
||Velocity vector of the satellite at the center of each video frame||List of float64 triplets||meters per second|
Notes and Explanations
- Frame duration: The exact duration and temporal separation of each video frame varies slightly depending on specific collection characteristics. The actual values are availalable in the GeoTIFF metadata.