International Archives of the Photogrammetry, Remote Sensing
If the request is for several layers, the layers are stacked on top
of each other in the order requested. There are optional methods
for per layer image enhancements that can be set in a
configuration file. If there is a time-out exception before all
browses have been retrieved, the missing browses are indicated
by drawing their wire-frame outlines on top of the mosaic.
The returned image file format is selectable as JPEG, PNG or
GeoTIFF. The addition of GeoTIFF as an output option makes
it possible to easily integrate the result in other GIS systems.
6. CONCLUSIONS
The WMS Image Server implementation was very successful
and has already proven a valuable tool for exploring the content
of the MUIS archives. Figure 10 is an example of an inventory
of new images acquired during last week.
6.1 Performance
The performance is very good, even on low-end computer
systems. The WMS Image Server was installed at ESRIN on a
dual processor Intel Xeon server. Examples of response time for
a GetMap request is less than 1 sec for a single browse, and 20
sec for a large mosaic including 200 browse images.
» and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
6.2 WMS protocol
The GetCapabilities request has been found not fully suitable
for handling a whole set of satellite images like the MUIS
Catalogue. The time specification could be improved to better
suit satellite imagery. The definition of today with the use of
the term CURRENT could improve this matter. Other question
in the same area is how to describe periodic data, with missing
data in the series.
REFERENCES
OpenGIS Consortium Inc. 2002. Web Map Service
Implementation Specification version 1.1.1.
http://www.opengis.org/techno/implementation.htm
Figure 10 Last weeks acquisitions of MER
IS images, presented in the UTM projection.
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