Focus plus context visualization can be used in augmented reality to improve the visual perception of the augmented scene. In the scope of in situ or on-patient medical data visualization, the focus plus context paradigm is used to improve depth perception for physicians showing the patient's anatomy as a focus region in the context of the patient's body. Volume clipping is one technique to realize focus plus context visualization. However, some of the existing methods for focus plus context visualization based on volume clipping do not run in full real time or are prone to artifacts. In this paper, we present an extension for two of these techniques to improve performance and image quality of the original approaches. We validate all the techniques in a markerless augmented reality environment. A 3D reference model is tracked by the application, and volumetric medical data are shown to the user at the position of the patient's anatomy. Our technique is able to handle multiple anatomic regions, although the main region of interest used in this paper is the face. Moreover, tracking accuracy is improved by the use of a hierarchical approach. From an evaluation of the proposed techniques, the results obtained highlight that all of them are free of artifacts, optimized for real-time performance, and improve the visual quality of the augmented scene. Graphical abstractDisplay Omitted HighlightsImprovement of smooth contours technique to achieve real-time performance.Improvement of visible background on MRI data to achieve higher visual quality.Use of a hierarchical ICP algorithm to improve tracking accuracy.Extension of the on-patient visualization for different parts of the patient's body.
['Márcio Cerqueira de Farias Macedo', 'Antônio Lopes Apolinário']
Focus plus context visualization based on volume clipping for markerless on-patient medical data visualization