Virtual graffiti consists of virtual or digital media applied to public locations, landmarks or surfaces. Virtual graffiti applications utilize

augmented reality Augmented reality (AR) is an interactive experience that combines the real world and computer-generated content. The content can span multiple sensory modalities, including visual, auditory, haptic, somatosensory and olfactory. AR can be de ...

and

ubiquitous computing Ubiquitous computing (or "ubicomp") is a concept in software engineering, hardware engineering and computer science where computing is made to appear anytime and everywhere. In contrast to desktop computing, ubiquitous computing can occur using a ...

to anchor virtual graffiti to physical landmarks or objects in the real world. The virtual content can then be viewed through digital devices. Virtual graffiti is aimed at delivering messaging and social multimedia content to mobile applications and devices based on the identity, location, and community of the user.

Mediums

This overall effort focuses on creating new mobile experiences based on merging

virtual reality Virtual reality (VR) is a simulated experience that employs pose tracking and 3D near-eye displays to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video games), educ ...

telepresence Telepresence refers to a set of technologies which allow a person to feel as if they were present, to give the appearance or effect of being present via telerobotics, at a place other than their true location. Telepresence requires that the user ...

, and

global positioning systems The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sys ...

. These experiences evolve over time based on the needs and capabilities of the users.

Location-based messaging

This medium regards a mobile user receiving or sending a message based on their location. The content quality is directly related to the accuracy of the user's location. These include experiences such as: * Searching where the nearest restaurant is and receiving a set of messages and coupons from nearby restaurant proprietors. * Receiving a message on their mobile device that there is traffic ahead with a suggested alternative route. * Coworkers receive a notification that an upcoming meeting has been moved to a new location.

Location anchored virtual reality

This involves anchoring a virtual reality experience at a physical location. Thus the experiences in the virtual world can only be had at a specific real location. Several use cases that are included here are: * A virtual command post can be set up at the scene of an incident. This command post involves the sharing of information in the virtual world but can only be accessed by those at the scene of the incident. * A set of blogs and media files are left at famous outdoor sculptures. Groups of friends can contribute, copy, and share files only while they are viewing the sculpture.

Background

The phrase "virtual graffiti" has existed for a long time and has been applied to various applications over the years. Originally, it referred to posting messages on electronic bulletin board systems. From there, it has developed in academia into contextual messaging applications.

Contextual messaging

Contextual messaging refers to leaving some type of context-specific annotation, e.g., a virtual

Post-it Note A Post-it Note (or sticky note) is a small piece of paper with a re-adherable strip of glue on its back, made for temporarily attaching notes to documents and other surfaces. A low-tack pressure-sensitive adhesive allows the notes to be easily ...

on a computer monitor, a time-sensitive message attached to a wall, or location-based graffiti on a physical object. Researchers at the University of Salford experimented with a

Cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

system in which a user could mark up a scene using 6-degree freedom sensors. Obviously, this is not suitable for immediate use or mass market applications, but it serves as starting point from which other work could be derived. During a research fellowship at the University of Georgia in 2003, Kit Hughes developed a system in which users with WiFi-enabled mobile devices could mark up buildings in downtown Athens, Georgia, with their own virtual graffiti via a process known as tagging. In this system, the buildings are selected on a map, and the graffiti is stored in a database that can be accessed from other mobile devices and the project’s website. A location-based messaging system for leaving virtual post-it notes on physical objects was developed at the

National University of Singapore The National University of Singapore (NUS) is a national public research university in Singapore. Founded in 1905 as the Straits Settlements and Federated Malay States Government Medical School, NUS is the oldest autonomous university in the c ...

. The system uses mobile devices as AR interfaces to view virtual messages associated with fiducial markers on physical objects. In a project from

Lancaster University Lancaster University (legally The University of Lancaster) is a public university, public research university in Lancaster, Lancashire, Lancaster, Lancashire, England. The university was established in 1964 by royal charter, as one of several pla ...

, mobile phones are used as digital mediums, using

RFID tag Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of a tiny radio transponder, a radio receiver and transmitter. When triggered by an electromagn ...

s to identify markable objects. The RFID tags can hold the identities of the last five people to leave graffiti. The graffiti itself is stored on a server. When another user comes within range of an RFID-tagged object, the associated graffiti is downloaded onto their mobile device.

References