AN OPENGIS WEB MAP SERVER FOR THE ESA MULTI-MISSION CATALOGUE 
T. Westin“ *, C. Caspar”, L. Edgardh“, L. Schylberg * 
? Spacemetric AB, Tingsv 19, 19161 Sollentuna, Sweden - tw@spacemetric.se 
b ESA Esrin, Casella Postale 64, 00044 Frascati, Italy — christophe.caspar wesa.int 
* SaabTech AB, 17588 Jàrfálla, Sweden — lars.schylberg@saabtech.se 
KEY WORDS: Remote Sensing, GIS, Inventory, Orthorectification, Database, Internet/Web, Web based, Satellite 
ABSTRACT: 
This paper describes the development and use of a Web Map Service (WMS) interface to the ESA Multi-Mission Catalogue (MUIS). 
This interface is compatible with the OpenGIS Consortium (OGC) version 1.1.1 specification so that browse products can be 
returned as geocoded images in a well-know geographic projection. This will allow them to be displayed on a web browser and 
merged with other EQ and GIS data available from servers already supporting the OGC WMS interface. 
MUIS contains over 200.000 browse image products from a large number of sensors flying on-board ESA and Third Party Mission 
satellites. The images represent a wide variety of sensor types, such as SAR, sweep scanners, push-broom scanners and conical 
scanners. 
The browse images in MUIS are stored in their original sensors coordinate system. This makes it necessary for the WMS server to 
rectify them to match the geographic projection requested in a WMS query. This process is performed on-the-fly. The full set of 
EPSG namespace projection codes are supported in the rectification, in addition to the OGC specified AUTO namespace projections. 
The rectification is based on a rigorous geometrical model for the space/image acquisition, taking sensor model and orbital 
constraints into account. The acquisition model is reconstructed from the browse metadata. It also makes orthorectification possible, 
by using an on-line global DEM. 
The Open GIS Web Map Server for the MUIS catalogue will enable WMS compatible clients to utilize the ESA products in an easy 
and standardized way. 
1. INTRODUCTION 
The OpenGIS W MS interface specification provides an easy Detected fires ; 
way to query Geographic Information and retrieve it as a | Be 3 
graphic representation other the Internet. The query hides the | e % Zn 
structure of the data on the server side and can serve in a d ^ = 
transparent and similar way various types of data be they raster 
(for e.g. satellite data) or vector (coastlines, fire location...). 
  
The query allows a precise control over the required geographic 
projection, bounding box and returned image dimension so that 
a client application can easily retrieve and merge information 
from distributed servers possibly maintained by various 
organizations. 
The following picture (Figure 1) illustrates the potential benefit 
resulting from the use of a WMS interface. On the left side, a 
map of fires detected in Northern Spain is displayed. These 
fires have been detected by the ATSR2 instrument on-board the 
ERS2 satellite. The actual ATSR2 frame used for that detection is 2 of 3 interface us 
shown on the left represents what a user can already obtain Feu DEAR ORIS ESSEN 
today via the existing MUIS interface (EOLI). On the right all 
data have been merged using a simple client accessing the à; | 
to the MUIS satellite image archive, so that its browse images 
various data sets via OGC WMS interfaces easing the d 
interpretation. of the satellite image and showing in this can be made available to WMS clients (Figure 2). The WMS 
particular case that what could have been originally interpreted Image Server was developed for ESA by Spacemetric, With 
has smoke from the stand-alone image is much more likely to SaabTech as subcontractor. 
be clouds unrelated to the fires. 
   
The WMS Image Server (WIS) provides such a WMS interface 
  
* Corresponding author. 
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