Geography Reference
In-Depth Information
3D Visualization
A 3D model can be saved in many formats, only a few of which can be easily
opened directly in a web browser, i.e. without the necessity to add a plug-in and/or
customize the Web browser in some way. The web presentation of 3D models
created from the Building Passport and in the CityGML format requires their
transformation into a different form. Both 3D models created in ArcGIS from the
Building Passport and CityGML data can be transformed to X3D format.
The CityGML format can be displayed in a web browser using a plug-in, which
is an obstacle to use. A number of programming libraries in JavaScript language
that display 3D information in the web browser have been developed in recent
years. Such a technology is the X3DOM library, which renders data stored in the
X3D (
eXtensible 3D
) format. A 3D model made in the ArcScene module can be
exported to VRML (
Virtual Reality Modeling Language
), which can be
transformed through freely available tools to X3D. This conversion is not difficult,
as X3D is based on VRML. The conversion of CityGML is not complicated either.
Although both formats are based on XML, CityGML is transformed into X3D using
an XSLT (
eXtensible Stylesheet Language Transformations
) stylesheet and XSLT
processor. The issue of the XSL transformation of 3D building data is described in
detail in Herman and
ˇ
ezn´k(
2013
).
The advantage of X3DOM is the relatively simple construction of 3D scenes and
also considerable support in different web browsers, not only on desktop com-
puters, but also on mobile devices. X3DOM is thus useful for developing 3D
navigation applications for these devices. It is planned to place the described
X3D model on the Department of Geography website or, alternatively, the Faculty
of Science website (the first version of this 3D model is shown in Fig.
2
).
Future Development
The previous sections showed the various ways of utilizing detailed data about
buildings, and the various options available. These data, whose acquisition is not
cheap, can be assessed mainly by multiple applications. In addition to the examples
mentioned above, these data can also be used for interactive mobile applications for
navigation. As mentioned above, CityGML and the Building Passport are con-
ceived quite generally and the indoor navigation issue requires an extension or
modification of these general data models. However, creating functional interactive
indoor navigation may not require further transformation into a new specific format.
The navigation extension that is designed to work with different types of 3D
geometry is IndoorGML. CityGML, IFC, KML (
Keyhole Markup Language
) and
2D digital data represent, for IndoorGML, sources of geometry. IndoorGML will be
derived from these datasets and contain mainly topological data supplemented with
semantic information. Original technologies are also used for the visualization of
