Introduction of SVG as a Data Interchange Format for Architectural
Documentations
Giinter Pomaska
Faculty of Architecture and Civil Engineering, Bielefeld University of Applied Sciences, Germany
gp@imagefact.de
CIPA Working Group VII - Photography
Keywords: Architecture, Internet / Web, modelling, architectural heritage conservation, vector graphics
Abstract:
Web tools provide software for generating data formats and interactive viewing. Since the bandwidth of the Web is still limited, not
by technology but accessibility of hardware, several companies introduced their own formats. Targeting to small file formats and
speed.
One can observe that since 1997 3D environments are published on the Web. Numerous software packages were released to the
market. Lots of them escaped soon without reaching importance. Due to the proprietary formats and the limited bandwidth of the
Internet connections most of them became failures. VRML, virtual modelling language, was introduced to create and model virtual
environments. This standard, defined by the Web 3D consortium, is more used for off-line presentations instead of distributing 3D
worlds via the Internet.
SVG (scalable vector graphics) introduced in 2001 is limited to 2D and should be the answer of the Web community to Macrome
dia’s Flash. SVG is defined by the World Wide Web Consortium (W3C) for 2D vector graphics. The success of SVG lies in its
standardisation and unification of this XML-based language. With SVG interactive viewing and animation of graphic content is
possible. A visitor of a Web site can zoom through maps and drawings, containing a huge amount of data. The quality of the presen
tation is high and even loss-free despite very large-scale factors.
Users of SVG need conversion tools for transforming existing data to that format. Viewers are available as stand-alone software or
plug-ins for Internet browsers. Designing Web pages with SVG requires some knowledge of the XML concept behind. This contribu
tion will discuss the usefulness of SVG for architectural drawings and some kinds of thematic mapping. First experiences with fa
çade drawings of Prussian classicism are presented.
1 FLASH OR SVG?
SVG (scalable vector graphics) is the World Wide Web Consor
tium (W3C) standard definition for interactive 2D Web graph
ics. This format includes text, bitmaps, vector graphics, anima
tion and interactivity - everything from one source. SVG for
mats can be generated with simple text editors, XML tools or
converters. SVG files scan be viewed with stand-alone viewers
or browser plug-ins.
Flash is a proprietary format for animations from Macromedia.
The format far spreads and is supported by Macromedias pow
erful animation tool. Despite this software there are several
good reasons to apply SVG.
SVG can be used without sophisticated authoring software; a
simple text editor is sufficient. Easy access via script languages
is provided. The format is very well structured; the source is
readable as a text format, while Flash is embedded in binary
formats.
Referencing of external images enables easy updating of SVG
presentations. Flash takes advantage from embedded images.
But updating means recompiling. SVG references images and
supports a much wider colour space and colour management.
Flash animations are replayed as a series of single frames.
Every image is precalculated and stored in the animation. SVG
has extended features by applying interpolations between two
positions. This results in a much better structured and shorter
code.
The Web community provides resources like tutorials, scripts,
software and application samples. Not least SVG benefits from
the advantages of a non-propriety standard.
2 RASTER AGAINST VECTOR DATA
A raster file represents a matrix with colour intensity values.
Zooming in or out is provided by extrapolation or interpolation
of neighboured pixels. Loss of quality and information is ac
cepted.
Vector data are defined by co-ordinates (points) and path seg
ments like lines, curves (bezier, splines) and others. The
connection between two points is a path segment. A closed path
segment defines a surface. Two points can be connected via
infinite paths to each other. The shortest way is the straight line.
Other ways need appropriate parameter definitions. Paths build
the mathematical shape to which the visual attributes like col
our, fill mode or line thickness are applied.
The quality of appearance of a vector-based graphic is inde
pendent from its zoom factor. The amount of memory is re
duced compared to raster graphics. Therefore less transfer time
