A Colorized Sub-aperture Image (CSI) is a Capella Spotlight mode collection processed to accentuate manmade objects, angular features, and objects in motion in a scene with vivid colors. During the Spotlight data acquisition, the satellite’s antenna beam is focused on a point of the earth for an extended period—tens of seconds. In data processing, this long synthetic aperture is divided into a set of up to 9 single-look sub-apertures generated from different squint angles across the duration of the collection. For GEO, GEC, and SIDD image products, the sub-apertures are combined through multi-looking to provide images with remarkably low speckle and enhanced radiometric resolution. The CSI processing progressively colorizes each sub-aperture using a cool-warm colormap and combines them into a 3-band detected image. Manmade features, even those partially obscured by vegetation, will typically reflect strongly from a single sub-aperture and thus ‘pop’ out in a single color of the CSI image. Objects in motion will render as a rainbow, representing the displacement of the object in each sub-aperture, with blue indicating the first sub-aperture and red indicating the last sub-aperture. Features such as tree canopies or brush generally reflect energy equally in all sub-apertures and will render grayscale. Capella’s CSI is geocoded and terrain corrected so that it can be combined with other geospatial data and viewed with a wide range of geospatial software. CSI is currently in a beta state of release. Capella is collecting user feedback, and some aspects of the product will change over time.
The following screenshot shows a Colorized Sub-aperture Image. The inset reveals a structure that reflects strongly from a certain sub-aperture and is thus colorized in red.