Information Technology Reference
In-Depth Information
6.2 Creating and Following
Hyperlinks
We model a hyperlink as a binary association between to document entities. It is
symmetric and can be traversed in both directions. These two-way links follow the
original hypertext principles introduced by Bush [12] and Nelson [102] and stand in
contrast to the reduced model of one-way hyperlinks known from the World Wide
We b.
In the early design phase, we investigated how students and colleagues make tra-
ditional handwritten references in documents. We observed that these are typically
not made within the text but in the left or right margin of the document, leading
to clearly visible references. Inspired by this practice, we opted for a spatial differ-
entiation between the actual document and association areas. In these rectangular
areas beside and above the document, users can create and follow hyperlinks. Asso-
ciation areas are not only printed on paper documents, but also displayed in digital
documents.
A key issue of our interaction design is the separation between a
generic associ-
ation gesture
and
different association areas
, which act as end points for the gesture
and represent different scopes. This combines intuitive interaction with versatility
and predictability even with the restricted feedback capabilities of a Pen-and-Paper
User Interface.
Our approach relies on pen gestures for several reasons. First, the user makes an-
notations with a digital pen. Using the same pen for linking tightly integrates both
interactions. Second, in contrast to gestures performed with fingers or hands or ma-
nipulations of the physical shape of a document, no further tracking infrastructure
than the digital pen - which is already used for annotations - is necessary. While
at a first glance, multi-touch seems compelling for associating two link anchors in
one single step, our experiences showed that users typically first select a first link
anchor and then seek for the appropriate second position of the association. This
is better served by an interaction which is divided into two steps. Finally, pen ges-
tures are very flexible. It is possible to mark and link small passages, but also entire
documents. Pen gestures can be made both on paper and on pen-enabled displays.
In contrast, linking documents by physically bringing them together is intuitive for
entire documents but not for specific sub-passages within a document. Moreover,
moving or collocating digital documents requires a different interaction than mov-
ing or collocating physical documents.
In the following, we first present the pen gesture for creating hyperlinks and
then provide more details on the different types of association areas this gesture is
performed on.
Association Gestures
Similar to the interaction technique for annotating documents, our technique for cre-
ating hyperlinks is designed to be minimally invasive and highly compatible with
existing practices of creating references. The starting point are informal handwritten
