New Augmented Reality Applications - Teaching through Multi-User Virtual Environments - page 373

rize it instead of understanding it. AR can
improve that.

tive 3D viewer to render the results. This viewer
works as a VRML plug-in for Internet browsers.
With the plug-in installed, the browser can open
a file with the VRML extension and display the
models contained in it.
Relating to the applications of Augmented
Reality, we have modified current programs and
developed new applications. This is because we
wanted to incorporate new features, like new
markers with associated named structures. We
also implemented a user friendly graphical inter-
face that can be run by the student, thus enabling
autonomous learning.
To modify existing AR applications and build
new ones, we need to take into account that
ARToolkit uses a set of additional libraries. For
example, ARToolkit provides tools to capture
images from video sources, process those images
to optically track markers in them, composite
synthetic and real-world contents, and display
the resulting images. For this, there are libraries
such us Direct Show Video Library (DSVideoLib),
openVRML and OpenGL.
DSVideoLib is a DirectShow wrapper sup-
porting concurrent access to frame buffers from
multiple threads. This library is useful for devel-
oping applications that require live video input
from a variety of capture devices. In ARToolkit,
the configuration of the video input devices is
specified in an XML file, conforming to the
DSVideoLib XML schema. In our system we
use different XML files to identify the webcams
used in our system.
Figure 4 shows the data path used by our sys-
tem to transfer the video stream from the input
camera, through the analysis and rendering stages,
and to the output display screen. The process uses
computer vision algorithms to identify the mark-
ers. Marker identification looks for a pattern in the
input video stream. This is achieved by converting
each input image into a binary one and identifying
the black marker frame. There may be more than
one marker in each input image. Once the mark-
ers are identified, their positions and orientations

• Study the structure of clays, their lay-

ers, and the cations and anions they may
incorporate.

• Understand the differences between crys-

tals and glasses according to their inner
structure, because crystal structures are ar-
ranged in 3D while glass is amorphous.

• In these classes, X-ray diffraction, the

crystalline systems and crystallographic
planes are also studied.

• Study ceramic pigments and their impor-

tance in ceramics, with regard to their
inorganic properties and structure. This
is a topic related to Advanced Chemistry
Laboratory.

methodology for Introducing AR
into Inorganic Chemistry education

Introducing AR into Inorganic Chemistry edu-
cation is accomplished in three different phases
with three different methodologies. First we use
a methodology to design models and implement
structures using VRML (Virtual Reality Model-
ing Language). Our second methodology is for
introducing AR into the classroom. The third
methodology is for coordination and interaction
during the classes.

Methodology for the Design and
Implementation of Structures

To describe the design and implementation of
models and structures we need to explain how
Chemistry and Computer Science relate to each
other in our AR system. The Computer Science
part deals with the implementation of interactive
3D graphics that represent the different crystalline
structures that we want to study. These graphics
have been built using VRML. In order to program
in this language, we need a text editor. VRML
allows coding the models and supports an interac-