Nowadays, spatial data are totally widespread in mobile
applications. They are present in games, map applications, web
community applications and office automations. However this
kind of
spatial
information potentially
needs a large display area
and
the hardware constraint related to the limited screen
dimensions
creates
many
usability
challenges.
Our investigation
in the last few years to find solutions to these challenges
has led
us to the discovery of general usability principles that a well
-
desig
ned interface should adopt. In this paper we describe the
mental path we have followed to derive those principles from the
experience gained
in developing
mobile interfaces
for different
application
domains. The principles are formalized in terms of
two in
teraction design patterns, specific for mobile interfaces
managing spatial data. They extend existing HCI patterns and are
completed, as usual, with concrete examples of their applications