International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 
«switch» 
«ext xot." ys" "stylec"stroke:...; fill:...; font-size:20;" 
systemLanguage="en"> 
Telephone Number 
</text> 
<text x="..." y="..." style="stroke:..; fill:…; font-size:20;" 0:" 
systemLanguage="el"> 
Api8uóc TuAepóvov 
</text> 
</switch> 
In case the web page that appears after users’ selection on a 
highlighted area is in SVG format and there is a need for 
embedding a raster image, SVG uses the «image? element as 
follows: 
«image x- "10" y="20" width-"200px" height-" 150" 
xlink:href="testimage.jpg"> 
5. DATA DISSEMINATION AND INTEROPERABILITY 
ISSUES 
SVG is an XML language enabling users to “read” the 
information contained in SVG files. This information 
concerning both geometry and descriptive data, in some cases 
has to be used in other applications or disseminated among 
different users. The solution proposed is the use of Geography 
Markup Language - GML. GML is an XML standard developed 
by the Open GIS Consortium - OGC designed to support 
interoperability among different data models and feature 
representations by providing a common data model, a set of 
basic and sophisticated geometry tags to describe the spatial and 
non spatial features (OGC GML, 2003). 
Based on XML technologies (XML and XML Namespaces), 
GML is extensible, supports definitions of profiles, is open and 
vendor independent. The value of using the GML is well 
understood when geographic data have to be transported. to 
other recipients in heterogeneous environments. Based on the 
standard mark-up elements, the receiving party knows exactly 
what each data component means and how to extract it so that 
nothing gets lost or distorted in the transport and translation 
process. In order to achieve that, the receiving party gets apart 
from GML files the corresponding application schema. The 
application schema is the implementation of a schema language 
that models geographic information in GML and defines rules 
for application schemas. Also defines standard elements and 
types for use (Portele, 2004). 
Whenever interoperability issues have to be taken into account, 
the standard procedure that has to be followed is the 
transformation of the source data files to GML format. This 
intermediate phase is considered necessary in order that 
potential users are capable to utilize the GML tiles without 
facing any interoperability problems (Figure 5). GML upholds 
the principle of separating content from presentation, thus a 
styling mechanism is required to display GML data. Potential 
graphical display formats apart from SVG are the Microsoft 
Vector Markup Language (VML) and the X3D (Lake, 2003). 
6. BENEFITS 
The huge amount of existing - large and small scale - data may 
benefit from the XML technology and more specifically from 
SVG. There are a number of converters enabling users to easily 
150 
  
    
   
  
  
    
   
  
  
  
  
  
  
  
transformation 
source SVg 
file file 
or 
source gml > svq 
file file file 
  
  
  
  
  
intermediate file for 
transport and storage use 
Figure 5: Alternative approaches to SVG result 
publish CAD, PDF and other popular format projects online as 
SVG, the open-standard W3C recommendation for vector 
graphic viewing on the web. The flawless conversion process 
outputs compact SVG that can be viewed in the free viewers 
which offer printing, zoom, pan, copy, and many other features. 
The converters automate many of the formerly manual 
processes associated with deploying and managing the 
publishing of files on web sites. More specifically the 
conversion process and the resulting graphics have the 
following characteristics: 
e Maintain the integrity of the original files 
e Have the option to "invert" the colour scheme, which 
transforms the standard black background to the web 
standard white background and at the same time 
change any line colours that would appear to be 
"washed out" when viewed with a white background 
e Save as SVGZ compressed files for delivery 
e Convert single files or whole directories 
e All the hard earned data that is in the block attributes 
is maintained, created at easily accessible metadata 
e Viewers are free, unlike other proprietary viewers 
available on major platforms and OS's 
e XML style of document structure means edits can be 
done in any text 
7. CONCLUSIONS 
The SVG format is emerging through the cooperative efforts of 
the World Wide Web Consortium (W3C) and its members. To 
Web developers, SVG will look and feel very familiar, thanks to 
its roots in XML. SVG is text based; therefore, coding 
techniques can be learned by leveraging the work or code of 
others. This drastically reduces the overall learning curve. The 
JavaScript language and Document Object Model (DOM) will 
be very familiar to people who use DHTML. Developers who 
use JSP, PHP, and ASP for HTML or text content today will 
now be able to create graphics in much the same way. 
SVG is text based and works seamlessly with current Web 
technologies like HTML, GIF, JPEG, PNG, SMIL, ASP, JSP, 
and JavaScript providing to the user full compatibility. 
Graphics created in SVG can be scaled without loss of quality 
across various platforms and devices. SVG can be used on the 
Web, in print and even on portable devices while retaining full 
quality. 
Sophisticated user interfaces or even full-blown on-line 
applications can be created with SVG. And because SVG is text 
based, the text inside graphics can be translated for other 
geographies quickly, often collapsing localization efforts to 
days instead of weeks. 
Interna 
Adobe 
Carto:T 
Lake F 
SVG. | 
OGC t! 
Implen 
Portele 
AGILE 
Savage 
W3C 
Specifi