Information Technology Reference
In-Depth Information
15.7
Description of the AR System
In order to perform the fractal-like immersion in the Past, from a macro level of the
real place of the archaeological site to a micro one, that of material textures, with the
purpose of presenting to the public the immaterial heritage in context, we decided
to use mobile devices, i.e. Android smartphones.
These implement the “video view” with the integrated video camera, which
presents the advantage of a wider visual field, and the fact that the lags of the real
image and of the rendered virtual object are comparable.
The AR experience on the smartphone is explained below:
the GPS receiver and the compass for location-based AR, or video camera for
image recognition, identifies the user localization and performs an image of the
“reality”;
the haptic technologies (touch/multi-touch screen) and the sensors from the
mobile devices (accelerometer, gyroscope, compass) translate the movements/
user position/user behaviour related with the real scene and objects;
the AR application searches for the virtual information, associated with elements
from the real environment (geographic position or a visual element) texts,
images, 3D models, videos, sounds, web site;
the digital information is presented in a visual and/or aural manner, and syn-
chronously with the real world.
For natural integration of the virtual information, the camera has to perform
perspective projections of the real 3D world in 2D plane images. The virtual object
is modelled in a reference system and generated over the live video stream using
low-level graphic functions. The AR system uses information about the real scene
(if available, after a previous scene modelling) in order to correctly render the
object.
For the graphical object to appear in the right place, it is necessary that the
AR system evaluate the position of the object in the real world, its orientation and
dimension. This process is called the 2D alignment of images in a real 3D scene.
15.8
The AR Application
The process of fractal-like immersion was implemented through the augmentation
of each stage, starting with the chosen geographic location and ending with the
materials/textures and colors specific to the prehistoric objects.
The application is launched in
geo-based mode
, which is using the data read by
the GPS receiver and the compass, which for all intents perform a geographic “scan”
of the village landscape.
The POIs identified represent the a prehistoric settlement and the place of
the experimental reconstructions, and are displayed as icons on a Google Map
