Implementation of the Automatic Processing Chain for Ares

DLR and GFZ are procuring the airborne hyperspectral scanner ARES (Airborne Reflective and Emissive Spectrometer) to be operating from autumn 2005. In order to ensure the first fully automatic processing environment for hyperspectral airborne scanner data working without any user interaction, a complete processing chain for hyperspectral data is designed. It includes an automatic invocation of system correction, parametric geocoding and atmospheric correction, as well as the archiving and filing of the resulting data products. This task is performed relying on an operational processing and archiving environment, installed at DLR, where the whole processing chain is embedded. It empowers the provider and the user of hyperspectral data to utilize a web interface making the data stock and status transparent. It further grants the operator access to a professional processing and archiving environment. This ensures an automated generation of standardized data products, allowing a reproducibility of the data at any time. INTRODUCTION DLR (Deutsches Zentrum für Luftund Raumfahrt) and GFZ (Geo-Forschungszentrum Potsdam) are acquiring the airborne hyperspectral scanner ARES to be operating from autumn 2005, being available for the scientific community from 2006. In order to ensure the first fully automatic processing environment for hyperspectral airborne scanner data working without any user interaction, the whole processing chain is embedded into the 'Data Information and Management System' (DIMS) (Mikusch et al., 2000 (i)), an operational processing and archiving environment installed at DLR. The following objectives were pursued: automation and standardization of the processing environment and the resulting data products, ensuring a high quality data standard, utilization of a professional web interface making the data stock and status transparent to the user, plus offering access to a professional archiving environment. DIMS provides an archiving subsystem as well as a generic processing environment and a searchable database including a public access via the WWW. The processing steps embedded into DIMS include system correction, orthographic rectification and atmospheric correction, which all rely on well-established software packages operating for several years. A product model for the automatic processing of airborne optical scanner data at Level 0 and 1 (raw data and system corrected data) has been presented in by Strobl and Habermeyer, 2001 (ii) and Habermeyer et al., 2001 (iii). It is used in this context and allows the fully automatic ingestion of the data in the processing and archiving system. In the course of the orthographic rectification by ORTHO (see Müller et al., 2002 (iv)) the attitude and position data recorded during datatake are synchronized with the scanner data and geo-referenced by the use of a Digital Terrain Model. This can be provided by the customer. In case no DEM is available the processing © EARSeL and Warsaw University, Warsaw 2005. Proceedings of 4th EARSeL Workshop on Imaging Spectroscopy. New quality in environmental studies. Zagajewski B., Sobczak M., Wrzesień M., (eds) system relies on a digital elevation database operated at DLR and called W42 (Roth et al., 2002 (v)). The task of the atmospheric correction is the calibration of each pixel to ground reflectance. This is done by the implementation of the software package ATCOR (Richter & Schläpfer, 2002 (vi)), which is based on the radiative transfer model MODTRAN (Berk et al., 1998 (vii)), and integrates the digital terrain model and meteorologic data. Each processing step is followed by a quality control giving evidence if the quality standards are met. A data model for geometric and atmospheric correction is described, including the components available at each processing level plus a set of parameters describing the dataset. This description of parameters on the one hand facilitates the traceability of the processing steps, while on the other hand enables the user to view all relevant parameters, when inspecting the data catalogue. The work is structured as follows: Based upon the data model the design (previously shown in (viii)) is revisited and the implementation of the processing system is explained, where the interaction of the individual processing components between each other and with the generic processing environment are shown. In this context an overview of DIMS is given, with a stress on those components actually employed for our purposes. In the following the organisation of the processing system is outlined in combination with an explanation of the work to be done to employ the capabilities of DIMS for the processing system for ARES. An introduction of the sub-systems for system correction, geocoding, the digital elevation database and atmospheric correction follows. An outlook of the work to be done concludes this paper. COMPONENTS OF THE DATA INFORMATION AND MANAGEMENT SYSTEM DIMS (Data Information and Management System) (for an overview see e.g. Mikusch et al., 2000 (i)) is a generic processing and archiving environment for the purpose of providing services within the framework of Earth observation product generation, storage, ordering, and delivery. It consists of several components providing a global product catalogue, storage media transparence and scalability with respect to storage capacity and data modelling. The parts of DIMS employed for our purposes are: the Product Library, the Processing System Management and the Operating Tool. Their interaction is shown in Figure 1. The Product Library (PL) is responsible for the long-term storage and availability of Earth observation products. It consists of an extensible product inventory with optimized geo-spatial search capabilities and a product archive using a robot media library. In DIMS the PL handles input and output of processing systems, input for user information systems, and is the source for product delivery to end users. For a more detailed description of the PL see Kiemle et al., 2001 (ix). The Processing System Management (PSM) provides an interface between the sensor-specific processing algorithms and the processing and archiving facility (x). Its main functions can be identified as enabling input product retrieval from and output product transfer to the PL, and production request handling.