Abstract
RapidEye is a leading provider of quality high-resolution satellite imagery. With a constellation of five earth observation satellites, RapidEye images up to five million square kilometers of earth every day, and adds over one billion square kilometers of imagery to its archive every year. The satellites are equally phased in a sun-synchronous orbit which allows for the possibility of imaging any point on the Earth (between 75 ͦS to 75 ͦN) each day. As RapidEye data features a combination of wide area repetitive coverage and five meter pixel multi-spectral imagery covering visible and near infrared wavelengths, it is a natural choice for many industries and government agencies.
Users of RapidEye imagery count on consistent data, regardless of the satellite used to take the image. However, slight variations inherent in custom manufacturing and different experiences on-orbit mean each imager is unique. To ensure a consistent response across the constellation, each instrument is calibrated to the other instruments in the constellation to a very high degree. This calibration is updated routinely and fosters the creation of consistent data over the lifetime of the fleet. This paper will detail the lifetime intra-constellation calibration of the RapidEye sensors over pseudo-invariant calibration sites (PICS).
The use of these sites for the purposes of calibrating on-orbit sensors is well documented. RapidEye uses over twenty sites, further broken down into 25x25 kilometer tiles, to not only monitor the lifetime trends of the individual sensors but also to compare each sensor’s response to the rest of the fleet. Each tile is evaluated individually and compared to the other tiles from the same site, each site is compared to the other sites, and each band is compared to the same bands from the other spacecraft. By breaking down the inter-satellite comparisons to the site/tile level, we are sure to only use data of appropriate quality and stability. Vicarious and inter-satellite cross calibrations have been and are currently used to ensure the absolute response of the RapidEye sensors generally agree with results obtained from the PICS approach. The agreement between absolute measurements and the PICS approach gives confidence to the calibration processes and ensures RapidEye data is accurate and independent of which individual instrument was used to obtain the imagery.
Lifetime Intra-Constellation Calibration of the RapidEye Sensors over PICS
RapidEye is a leading provider of quality high-resolution satellite imagery. With a constellation of five earth observation satellites, RapidEye images up to five million square kilometers of earth every day, and adds over one billion square kilometers of imagery to its archive every year. The satellites are equally phased in a sun-synchronous orbit which allows for the possibility of imaging any point on the Earth (between 75 ͦS to 75 ͦN) each day. As RapidEye data features a combination of wide area repetitive coverage and five meter pixel multi-spectral imagery covering visible and near infrared wavelengths, it is a natural choice for many industries and government agencies.
Users of RapidEye imagery count on consistent data, regardless of the satellite used to take the image. However, slight variations inherent in custom manufacturing and different experiences on-orbit mean each imager is unique. To ensure a consistent response across the constellation, each instrument is calibrated to the other instruments in the constellation to a very high degree. This calibration is updated routinely and fosters the creation of consistent data over the lifetime of the fleet. This paper will detail the lifetime intra-constellation calibration of the RapidEye sensors over pseudo-invariant calibration sites (PICS).
The use of these sites for the purposes of calibrating on-orbit sensors is well documented. RapidEye uses over twenty sites, further broken down into 25x25 kilometer tiles, to not only monitor the lifetime trends of the individual sensors but also to compare each sensor’s response to the rest of the fleet. Each tile is evaluated individually and compared to the other tiles from the same site, each site is compared to the other sites, and each band is compared to the same bands from the other spacecraft. By breaking down the inter-satellite comparisons to the site/tile level, we are sure to only use data of appropriate quality and stability. Vicarious and inter-satellite cross calibrations have been and are currently used to ensure the absolute response of the RapidEye sensors generally agree with results obtained from the PICS approach. The agreement between absolute measurements and the PICS approach gives confidence to the calibration processes and ensures RapidEye data is accurate and independent of which individual instrument was used to obtain the imagery.