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資料可視化

王俞喬

國立臺北科技大學資訊工程系

Effective Visualization of Short Routes

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論文 / 作者 / 影片

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Effective Visualization of Short Routes

短途路線的有效視覺化

Patrick Degener, Ruwen Schnabel, Christopher Schwartz and Reinhard Klein, Member, IEEE

IEEE TVCG 2008

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摘要

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Abstract

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在這項工作中，我們開發了一種新的替代傳統地圖的方式，用於可視化在酒店、度假村或博物館中經常遇到的相對短的路徑。我們的方法基於對環境的3D模型進行扭曲渲染，使得可視化的路徑看起來是直的，即使它可能包含多個交叉點。

這有一個優勢，即圖像的觀者可以對沿途的環境有一個真實的印象，這使得在實際中追溯路線變得容易。我們提供了一種直觀的生成此類圖像的方法，並展示了進行用於評估扭曲圖像在未知環境中定位方面的優勢的使用者研究結果。

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Abstract

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Abstract— In this work we develop a new alternative to conventional maps for visualization of relatively short paths as they are frequently encountered in hotels, resorts or museums. Our approach is based on a warped rendering of a 3D model of the environment such that the visualized path appears to be straight even though it may contain several junctions.

This has the advantage that the beholder of the image gains a realistic impression of the surroundings along the way which makes it easy to retrace the route in practice. We give an intuitive method for generation of such images and present results from user studies undertaken to evaluate the benefit of the warped images for orientation in unknown environments.

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圖 / 表

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Images rendered by our method give the impression of looking along a path all the way to the destination

用我們的方法渲染的圖像給人的印像是沿著一條路徑一直望向目的地

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左上方的圖片顯示的是虛擬漫步環境中記錄的路徑。右上圖顯示的是施加薄板花鍵翹曲後的變形幾何。請注意，路徑已成功拉直，目的地清晰可見。二次變形的效果在左下圖中可以看到，在應用二次變形後，相同的路徑被視覺化。請注意，路徑周圍重要的細節現在也可以在路徑末端看到，而先前這些細節是被遮擋住的（例如樓梯和箱子）。右下角：如果路徑沒有明顯繞過障礙物，可能會出現遮蔽問題。明顯繞過障礙物

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左側顯示場景中的路徑，路徑上的樣本點顯示為紅色球體。在每個樣本位置上，路徑的切向量定義了一個平面。以樣本點為中心的正方形四角定義了輔助位置，用於限制空間變形的尺度。右側為變形後的路徑。所有樣本位置都位於在一條直線上。��On the left hand side the path in the scene is illustrated and the sample points on the path visualized as blue spheres. At each sample location a plane is defined by the path’s tangent vector. The corners of a square centered about the sample point define auxiliary positions that are used to constrain the scale of space deformation. On the right hand side the path after the deformation is depicted. All sample positions lie on a straight line of sight.

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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影像顯示了第 5.2 節所述的二次變換效果。�The image shows the effect of the applied secondary transformation as described in sec.5.2.

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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我們的方法在高度複雜（左）和長路徑（右）上失敗。�Our method fails on highly complex (left) and long paths (right).

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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使用者研究中使用的測試案例 1−4。�Test cases 1−4 used in the user study.

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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使用者研究中使用的測試案例 5−7。�Test cases 5−7 used in the user study.

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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步行時間（s）的平均值（μ）和標準差（s），地圖/影像顯示時間（秒）、初始定位所需時間（秒）和成功率。我們的方法比傳統地圖表現更好的平均值以粗體顯示

�Average (μ) and standard deviation (s) of walking times (s),

map/image display times (s), time needed for initial orientation (s) and success rates. The average values in which our method performed better than traditional maps are printed in bold-font

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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我們手動引入了輔助控制的非均勻比例調整，以改善目標區域的描繪和航路點之間的感知距離�We manually introduced a non-uniform scale adjustment of auxiliary control to improve the depiction of the target area and the perceived distances between waypoints

In the top left image a path that was recorded during a virtual walk-through of the environment is depicted. Four additional paths are generated by auxiliary points as described in sec.5. The top right image displays the deformed geometry after application of the thin-plate spline warping. Please note that the path was indeed successfully straightened and the destination is visible. The effect of the secondary trans-formation is visible in the bottom left image where the same path is visualized after the secondary transform was applied. Note that significant and important detail in the surrounding of the path is now visible also at the end of the path that was occluded before (e.g. the stairs and boxes). Bottom right: occlusion issues may arise if a path does not run clearly around obstacles

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結論

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結論

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我們將所述系統應用於兩個虛擬環境（一個小型城市模型和一個大型辦公大樓）中的幾條路徑。如第 4 節所述，所有路徑都是透過手動漫步記錄下來的，長度和轉彎次數各不相同。圖 5 和圖 7 顯示了七次互動式渲染的結果，每次渲染需要 10-15 分鐘。透過互動式回饋，我們手動調整了輔助約束的間距，以增加可視性。

We applied the described system to several paths in two virtual environments - a small city model and a large office building. All paths were recorded from manual walk-throughs as described in section 4 and vary in both length and the number of turns. Figures 5 and 7 show the results of seven interactive rendering sessions which each took us 10−15 minutes to generate. Using the interactive feedback we manually adapted the spacing of the auxiliary constraints to increase visibility.

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結論

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雖然理論上可以為路徑上的各個樣本指定不同的間距，但我們並沒有這樣做。在顯示的結果中，整個路徑的間距是一致的。在某些情況下，為了解決遮蔽問題，原始路徑也會稍作修改，如圖 2 右下方所示。在這種情況下，透過手動將路徑移離前景中的方塊來解決遮蔽問題。另外，也可以改變方框附近樣本的輔助約束間距來達到類似效果。不過，我們在實驗中發現，儘管我們的方法並不能明確保證路徑的無遮蔽描繪，但在大多數情況下並不需要手動調整路徑或輔助約束。

Although theoretically different spacings can be specified for individual samples along the path, we did not pursue this possibility. For the shown results the spacing was uniform along the whole path. In some cases, the original path was also slightly modified to resolve occlusion issues as shown in the bottom right of figure 2. In this case the occlusion was resolved by moving the path manually away from the box in the foreground. Alternatively, the spacing of the auxiliary constraints at samples near the box could have been changed to achieve a similar effect. However, we found in our experiments that a manual adjustment of the path or auxiliary constraints is not necessary in most cases, even though our method does not explicitly guarantee an occlusion-free depiction of the path.