Game Development Reference
In-Depth Information
Learning augmented reality methods
AR applications need trusted markers to show their tricks, like a magician saying,
"See that top hat? There will be a rabbit soon!", where the top hat is the reference
point. There are several types of reference points and each of them has their own ad-
vantages and spheres of application.
The following figure shows most common forms of markers:
The following are the short descriptions of these markers:
•
Symbol-based
: This is a basic method. It is the recognition and tracking of
special graphic markers that are officially known as
fiducial markers
or fidu-
cials (from the Latin
fiducia
, which means trust), but are sometimes referred
to as AR tags, tracking marks, artificial landmarks, and so on. In some cases,
slightly modified QR code markers can be used as well.
•
Image-based
: Graphic images such as photos or illustrations are split into ref-
erence points (the simplest way is to find a contrast frame around a picture).
For instance, some applications use the one-dollar bill as the real-world basis
that AR content will be created on, arguing that bills are the most common
pieces of paper with graphics on them that an ordinary person can get their
hands on. Such practice is used by programs such as Shimmer Augmented
Reality Viewer for iOS (
http://ionreality.com/shimmer/
), which allows you to
view 3D models in the AR space. In some cases, when very accurate recog-
nition tasks are the goal, the image-based method may require very powerful
CPU resources, because graphic images are split into thousands of markers
that are being tracked in real time. This is why there is a service called Xloud-
ia (
http://www.lm3labs.com/xloudia/
)
that makes such calculations in the cloud
computing to recognize complicated images on the server side.
•
Object-based
:Specialrealobjectsareusedasmarkers.Theycanbepassive
(only their geometry and contrast color will be used as markers) or active (they
will emit signals as light ones). Usually, they come in the shape of small cubes
or spheres. There are also some applications that track a user's face and use
their movements as input data.
