Virtual Fly-Over: A New Visualization Technique for Virtual Colonoscopy

Abstract

In this paper, we propose a new visualization technique for virtual colonoscopy (VC). The proposed method is called Virtual FlyOver , which splits the entire colon anatomy into exactly two halves. Then, it assigns a virtual camera to each half to perform flyover navigation, which has several advantages over both traditional fly-through and related methods. First, by controlling the elevation of the camera, there is no restriction on its field of view (FOV) angle (e.g., > 90 o) to maximize visualized surface areas, and hence no perspective distortion. Second, the camera viewing volume is perpendicular to each colon half, so potential polyps that are hidden behind haustral folds are easily found. Finally, because the orientation of the splitting surface is controllable, the navigation can be repeated at a different split orientation to overcome the problem of having a polyp that is divided between the two halves of the colon. Quantitative experimental results on 15 clinical datasets have shown that the average surface visibility coverage is 99.59±0.2%.

One-sided transparency : a revolution in visualization.

“…It was first proposed in [7] in 2006. This method aims to split the colon in half along its length, then view each half individually, figure 19.…”

“…The CVIP lab first introduced the fly-over visualization in [7] and has obtained a patent on the method. In order to advance previous work at the CVIP lab, this thesis focuses on improving the existing fly-over method.…”

“…Thus, the normal generation method must relate each normal to the previous normal. The method given here was presented for use in flyover in [7].…”

“…The work of this thesis adapts the existing fly-over method, with some key alterations. The main difference lies in the normal generation, which is different from the normal generation method previously outlined in [7]. This new method is simpler, equally effective, and provides a smoother viewing by aligning view up vectors to be normal to the centerline.…”

Enhancement of virtual colonoscopy system.

“…Other means of visualization include: flattening [11], unfolded cube projection [10], and 15 flyover [12] (developed by the CVIP Lab and patented). These methods will be elaborated upon in the literature review.…”