Ursula Marschalk

Comparison of DEMs derived from SRTM/X- and C-band

In February 2000, the Shuttle Radar Topography Mission (SRTM) successfully mapped the entire landmass between 60deg N and 54deg S using an Interferometric Synthetic Aperture Radar (InSAR). The data were acquired in Cand X-band and were independently processed to Digital Elevation Models (DEM) by NASA-JPL (C-band) and DLR (X-band). A commonly used source was the Position and Attitude Determination Record (PADR) generated by the Attitude Orbit Determination Avionics (AODA) system. The PADR file provides the orbit and baseline information. All C- and X-band data were systematically processed to 1 arc-second resolution DEMs. The X-band DEMs are globally available at DLRs German Remote Sensing Data Center (DFD). USGS provides the C-band derived elevation data in 1 arc-second for the US and globally a reduced version with 3 arc-second spacing. The presentation compares the X- and C-band derived elevation models. Starting from the individual verification results the correspondence of the SRTM DEMs with respect to height and location accuracy is investigated. Potential global and local discrepancies are discussed. Both datasets are compared to the Altimetry Corrected Elevations global DEM (ACE)

Production chain towards first calibrated and mosaicked TanDEM-X DEMs

The main product of the TanDEM-X mission is an interferometric DEM product that is finally calibrated due to residual systematic offsets and tilts and where different, generally two coverages, are mosaicked. Above this, a water mask is provided to support later editing of rough water areas. In this presentation the commissioning phase work to set the DEM production chain into operation is described and the first commissioning phase products are shown.

Scientific use of TerraSAR-X

TerraSAR-X is a new German radar satellite scheduled to be launched in May, 2007. Its lifetime will be five years. It carries a high frequency X-band SAR sensor that can be operated in three different modes and various polarizations. The Spotlight-, Stripmap- and ScanSAR-modes provide high resolution images for detailed analysis as well as wide swath data whenever a larger coverage is required. These high geometric and radiometric resolutions together with the single, dual and quad-polarization capability are innovative and unique features with respect to space borne systems. Additionally several incidence angle combinations will be possible and double side access can be realized by satellite roll maneuvers. The satellite will be positioned in an 11 days repeat orbit. The revisit time in the very high resolution Spotlight mode is 2.5 days for 95% Earths surface visible to TerraSAR-X.

W42 - a scalable spatial database system for holding Digital Elevation Models

The design of a scalable system for holding spatial data in general and Digital Elevation Models (DEMs) in specific has to account for the characteristics of data from various application fields. The data can be heterogeneous in coverage, as well as in resolution, information content and quality. A database aiming at the representation of world-wide DEMs has to consider these differences in the design of the system with respect to the structure and the algorithms. The database system W42, which is presented in the work at hand, is a scalable spatial database system capable of holding, extracting, mosaicking, and fusing spatial data represented in raster- as well as in vector-format. Design aspects for this task can be specified as holding spatial data in unique data structures and providing unique access functions to the data. These are subject of this work as well as first experiences gained from the implementation of part of the extensions made for the TanDEM-X mission.

Ten Years of Experience with Scientific TerraSAR-X Data Utilization

This paper presents the first comprehensive review on the scientific utilization of earth observation data provided by the German TerraSAR-X mission. It considers the different application fields and technical capabilities to identify the key applications and the preferred technical capabilities of this high-resolution SAR satellite system from a scientific point of view. The TerraSAR-X mission is conducted in a close cooperation with industry. Over the past decade, scientists have gained access to data through a proposal submission and evaluation process. For this review, we have considered 1636 data utilization proposals and analyzed 2850 publications. In general, TerraSAR-X data is used in a wide range of geoscientific research areas comprising anthroposphere, biosphere, cryosphere, geosphere, and hydrosphere. Methodological and technical research is a cross-cutting issue that supports all geoscientific fields. Most of the proposals address research questions concerning the geosphere, whereas the majority of the publications focused on research regarding “methods and techniques”. All geoscientific fields involve systematic observations for the establishment of time series in support of monitoring activities. High-resolution SAR data are mainly used for the determination and investigation of surface movements, where SAR interferometry in its different variants is the predominant technology. However, feature tracking techniques also benefit from the high spatial resolution. Researchers make use of polarimetric SAR capabilities, although they are not a key feature of the TerraSAR-X system. The StripMap mode with three meter spatial resolution is the preferred SAR imaging mode, accounting for 60 percent of all scientific data acquisitions. The Spotlight modes with the highest spatial resolution of less than one meter are requested by only approximately 30 percent of the newly acquired TerraSAR-X data.

A near-real-time service for the provision of ERS SAR products

ERS SAR data are used to support mapping and forecasting of sea ice, wind and waves and the management of coastal zones. These information improve e.g. ship routing and the detection of environmental impacts like oil slicks. A major key is the fast availability of this information at the relevant institutions. DLRs Remote Sensing Data Center operates a X-band receiving station as well as the German Processing and Archiving Facility for ERS and X-SAR data. Both systems were linked in order to implement a near-real-time service for the provision of products derived from ERS-SAR data. The data are acquired in Neustrelitz, transferred via network to the processing center in Oberpfaffenhofen and provided to the user, again via network. This chain currently supports the Federal Maritime and Hydrographic Agency of Germany (BSH) in Hamburg in its tasks like the ice service in the Baltic and North Sea, the monitoring of the German coast and the detection of oil slicks. The proposed presentation will describe the chain, the delivered products and the potential of this service for other applications fields like disaster assessment and management.