The Interaction Fidelity Model: A Taxonomy to Distinguish the Aspects of Fidelity in Virtual Reality

TL;DR

The Interaction Fidelity Model (IntFi Model) is presented, based on the human-computer interaction loop, which systematically covers all stages of VR interactions and helps teams to understand and discuss fidelity in VR.

Abstract

Fidelity describes how closely a replication resembles the original. It can be helpful to analyze how faithful interactions in virtual reality (VR) are to a reference interaction. In prior research, fidelity has been restricted to the simulation of reality - also called realism. Our definition includes other reference interactions, such as superpowers or fiction. Interaction fidelity is a multilayered concept. Unfortunately, different aspects of fidelity have either not been distinguished in scientific discourse or referred to with inconsistent terminology. Therefore, we present the Interaction Fidelity Model (IntFi Model). Based on the human-computer interaction loop, it systematically covers all stages of VR interactions. The conceptual model establishes a clear structure and precise definitions of eight distinct components. It was reviewed through interviews with fourteen VR experts. We provide guidelines, diverse examples, and educational material to universally apply the IntFi Model to any VR experience. We identify common patterns and propose foundational research opportunities.

Figures (19)

• Figure 1: The Interaction Fidelity Model differentiates between eight fidelity components that affect any VR interaction. The model is based on the Human--Computer Interaction Loop reenskaug_MVC_1979norman1986.UserCenteredDesign and extends a previous framework by mcmahan2016.UncannyInteration.
• Figure 2: Two examples of reference interactions that are virtually replicated in VR simulations. (top) Here, an interaction from the real world is reproduced. Picking an apple from a tree is a complex activity to be simulated virtually as the user's actions, the provided feedback, and the physical simulation are closely coupled. This is a recent implementation with a haptic device by deTinguy2020.weatavix which dynamically moves the sphere proxy into the user's hand when grasping. (bottom) Here, a fictional interaction is reproduced. The mythological magic carpet from Middle Eastern literature can be realized as a VR locomotion technique in many different ways medeiros2020.MagicCarpet. This is an early implementation by pausch1996.Aladdin. Copyright of the top-right images by deTinguy2020.weatavix and of the bottom-right images by pausch1996.Aladdin (modified by the authors). The images for the reference interactions have been generated with Midjourney.
• Figure 3: The Model-View-Controller pattern reenskaug_MVC_1979 from 1979 on which the IntFi Model is conceptually based: A user uses a controller to manipulate the model, which updates the view and is then seen by the user.
• Figure 4: The fidelity spectrum with approximate ranges from low, medium, and high to maximum fidelity with an example use case: implementations with different fidelity levels of somebody picking an apple from a tree. The reference interaction from the real world on the right side is defined as maximum fidelity. Copyright of the "High Fidelity" images by deTinguy2020.weatavix. The other images have been photographed or generated with Midjourney by the authors.
• Figure 5: (left) The reference interactions in the real world to be simulated: A surgeon and his team performing a laparoscopy. (middle) The user operating the VR training system. (right) The user's view inside the VE: the operating room and a virtual screen with the laparoscopic camera view. Images by Surgical Science, modified by the authors.