Multi-looking is a technique that generates images with lower speckle and increased image quality.

Capella satellites' agile design provides much longer dwell times in spotlight imaging mode. Capella's SAR sensors are able to generate high-quality image products with greatly reduced speckle because they are capable of imaging the same location on the ground for tens of seconds in spotlight mode.

The Capella system can provide a maximum ground range resolution of 0.5 m with 9 looks which provides substantial improvement in the image quality. The Capella multi-looked imagery is obtained by splitting a long synthetic aperture into a set of sub-apertures and then combining them to generate the GEO image product type. For this purpose, nine 0.5m resolution SLC imagery are generated with multiple squint angle each time that a Spot product is collected and processed. 

 

The below figure presents a comparison of 0.5m resolution SAR imagery that have been generated with a single look (left) and nine multiple looks (right). Multi-looking processing produces enhanced radiometric resolution with higher sensitivity to brightness changes and less noise. The single look image on the left has significant speckle noise but the multi-look version on the right has much improved image clarity and target detectability. The aircraft emerge clearly in the multi-looked image and are easier to distinguish than in the single-look image. The scene also contains backscatter variations over the grassy areas which are clearly discernible.

 

blobid0.pngImage quality improvement via the multi-look process. A short integration time is needed to generate single-look SAR images (left) and longer integration times generate Capella's 9-look imagery (right). Single-look and multi-look images have the same resolution, equal to 0.5 meter.   

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