L. Hong, S. Muraki, A. Kaufman, D. Bartz, T. He, "Virtual voyage: Interactive navigation in the human colon," Computer Graphics Proceedings, Ann. Conf. Series, pp. 27-34, 1997  Home/Search   Document Details and Download   Summary   Related Articles   Check

....of virtual space exploration. However, the great challenge still exists when we are asked to manipulate a 3D virtual scene only with a regular 2D mouse on a desktop PC. Most previous work in this direction focused designing intuitive user interfaces for controlling 3D rotations with 2D devices [6][17] Most of the aforementioned proposals use the direct manipulation metaphor. This metaphor is shown to be more comprehensible, predictable, and controllable than the delegation types of intelligent user interfaces in several application domains. However, it is still under debates which ....

....as a tool for control delegation. They use a third person view to specify the desired tasks, which is very different from the first person view commonly used in the direct manipulation metaphor. Other researches also suggest using vector fields [5] or force fields (such as potential fields) 21][6] to guide animation or navigation. However, most of them are reactive in nature, and no planning is incorporated to assist interactive tasks. 2.2. Path planning The path planning problem (or the so called Piano Mover s Problem) has been extensively studied in the past two decades. A good survey ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He, "Virtual Voyage: Interactive Navigation in the Human Colon," in Proceedings of SIGGRAPH'97 Conference, pp 27-35, 1997.

....and cPLP require little preprocessing. For most heuristics, the precomputation consists of creating the model hierarchy and computing simple summary statistics per node, such as the total number of primitives. This can be done quickly, even for a large model. On the other hand, other techniques [Teller91, Hong97, Zhang97] may require preprocessing times in the order of hours or days, even for relatively small models. Although occlusion culling algorithms, such as PLP, avoid rendering unseen geometry, they still may render small primitives that have little effect on the final image. As shown by El Sana et al. ....

Lichan Hong, Shigeru Muraki, Arie E. Kaufman, Dirk Bartz, and Taosong He, "Virtual Voyage: Interactive Navigation in the Human Colon," Computer Graphics Proceedings (SIGGRAPH 1997), pp. 27-34.

....dataset of a body part derived from diagnostic imaging data is displayed on a computer and made available for 3D navigation and analysis. Research virtual endoscopy prototypes are being developed and have proven useful for a variety of clinical applications (e.g. bronchoscopy [23] cholonoscopy [10] and minimally invasive surgery planning [1] Because of the computational costs associated with image production, work in this field has until recently concentrated on generating precomputed fly through animations [12, 19, 22] which makes these tools rather cumbersome to be used for the kind ....

....virtual angioscopy applications. However, current interactive virtual endoscopy systems are mostly based on surface rendering techniques, where volumetric data is automatically or manually segmented during a preprocessing step to extract boundary surfaces that are then rendered during navigation [23, 10]. These techniques have proven to be often not accurate enough for clinical examinations [29, 16, 7] In particular, since when using surface rendering only the interior surfaces of a cavity are visible during navigation, diagnostic capabilities are severely limited [17, 18, 22] Our aim is to ....

[Article contains additional citation context not shown here]

HONG, L., MURAKI, S., KAUFMAN, A., BARTZ, D., AND HE, T. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings (Aug. 1997), T. Whitted, Ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley, pp. 27--34. ISBN 0-89791-896-7.

....or surface boundaries within the volume in the context of direct volume rendering, and in particular, in the context of splatting. 2. Motivations and General Idea For many medical applications, important features in structures of the human body, such as nasal passageways [Stredney98] colons [Kaufman97] and even blood vessels need to be studied or simulated by navigating through a virtual simulation. These features may comprise only a small number of voxels in their cross sections. With the conventional splatting renderer, these fine structures are blurred and navigation is hampered by the ....

Hong, L., Muraki, S., Kaufman, A., Bartz, D., He, T., Virtual Voyage: Interactive Navigation in the Human Colon, SIGGRAPH'97 Conference Proceedings, August, 1997, 27-34.

....research is involved with prior specified goals, and therefore does not fulfill the requirements mentioned above. In these cases a start position and one or more goal positions are predefined and the calculation of the path is done in advance. A different problem is addressed by Hong et al. in [7]. In their Virtual Voyage the exploration of CT data of the human colon is assisted by an automated ride through the middle of the colon. From the CT data the wall of the colon is extracted and skeletonised. From this skeleton the middle of the colon is calculated. The start and end of the ....

L. Hong, S. Muraki, A. Kaufmann, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In Proc. of ACM Siggraph, pages 27--34, 1997.

....the need for endoscopy in high risk patients, for pre operative planning, training, and for viewing body parts where real endoscopy cannot function, for example, blood vessels. Such a simulation may also be a general medical learning tool, offering students a virtual tour inside the body [5]. By utilizing 3D sets of CT and MRI scans, such a system was developed at Algotec Systems Ltd, based on a 3D post processing workstation. Currently, that virtual simulation system focuses more on visual aspects by trying to simulate the inner views of real life endoscopy, and less on operational ....

....generated images to only viewing the anatomy of the organs. This may be useful, for example, for detecting bumps in the large intestine which are suspected of being polyps, or for viewing the organ structure and anatomy for a pre endoscopic plan of the path of the endoscope in high risk patients [5]. While this eliminates the ability to diagnose using this tool solely, it also produces undesired synthetic images in the course of training and general learning through a virtual tour , giving both the training and learning a far less realistic feeling. In order to overcome this drawback, it ....

L. Hong. S. Muraki, A. Kaufman, D. Bartz and T. He, Virtual Voyage: Interactive Navigation in the Human Colon. SIGGRAPH 97 Conference Proceedings, 27--34, 1997.

....[1] The disadvantage of this approach is that it creates many more triangles than MC. A major disadvantage of all volume to surface method is that reconstruction is not view dependent and therefore large portions of the generated triangle mesh are not visible from a given viewpoint. Hong et al.[8] used occlusion culling to reduce the number of triangles that is fed into the graphics hardware in each frame. The storage size of the mesh representation remains large, however. In contrast, the advantage of a ray casting approach is that it inherently performs an occlusion culling. Thus, its ....

....the need for endoscopy in high risk patients, for pre operative planning, training, and for viewing body parts where real endoscopy cannot function, for example, blood vessels. Such a simulation may also be a general medical learning tool, offering students a virtual tour inside the body [8]. By utilizing 3D sets of CT and MRI scans, the ray casting algorithm described above can be used to display shaded surface organs within the body, simulating real life endoscopy. CT, MRI and other scanning methods measure quantities such as the density (attenuation coefficient) or the magnetic ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz and T. He, Virtual Voyage: Interactive Navigation in the Human Colon. In SIGGRAPH 97 Conference Proceedings, 27--34, 1997.

....portals are clipped against the pre existing portals, leading to smaller and smaller visible windows , until no visible portal remains. This technique is simple and quite effective, and the source code (an SGI Performer library) is available for download from Luebke s web page. Hong et al. [49] use an image based portal technique similar to the work of Luebke and Georges [62] to be able to fly through a virtual human colon in real time. The colon is partitioned into cells at preprocessing and these are used to accelerate the occlusion with the help of a Z buffer at run time. 5.2 Large ....

Lichan Hong, Shigeru Muraki, Arie Kaufman, Dirk Bartz, and Taosong He. Virtual voyage: Interactive navigation in the human colon. In Turner Whitted, editor, SIGGRAPH 97 Conference Proceedings, Annual Conference Series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....the endoscope [4] The sensitivity is estimated to be in the order of 80 82 for small polyps. People eligible for screening often avoid the examinations, because of the associated discomfort [5] In the past few years, virtual colonoscopy (VC) has been developed as a patient friendly alternative [6]. First, the patient s colon is cleansed and transanally inflated with air. Subsequently, a 3D image volume is acquired of the abdomen by CT or MRI. Finally, the interior bowel surface is extracted and visualized, after which the physician virtually navigates through the colon and examines the ....

....is justified. Visualization Surface rendering (SF) is often applied in VC under the assumption that the signal change between wall and lumen is instantaneous. To avoid decimation, only those polygons may be submitted to the rendering pipeline that are visible from the viewing frustrum [6]. Information about the detailed structure of the mucosa, however, is omitted [22] In [22] it is demonstrated how the mucosal interface can be better visualized by direct volume rendering (DVR) Moreover, exploration of the tissue beneath the surface is supported Chapter 10: Imaging 941 by a ....

Hong L, Muraki S, Kaufman A, He T. Virtual voyage: interactive navigation in the human colon. Proc ACM SIGGRAPH Conf. ACM Press, 1997; pp. 27-34.

....polyps has proven to lead to a decrease in incidence [2] However, the traditional technique for detection and removal of polyps, optical colonoscopy, causes serious discomfort. In the past few years, virtual colonoscopy (VC) has been developed as a more patient friendly screening alternative [4][5] 6] In general, the VC procedure consists of the following stages. First, the patient s colon is cleansed and inflated with air. Next, a 3D image volume of the abdomen is acquired using CT imaging. The bowel surface is then extracted from the volume and visualized in a way similar to camera ....

L. Hong, S.Muraki, A. Kaufman, D. Bartz, T. He, 'Virtual voyage: interactive navigation in the human colon', Proceedings A.C.M. Siggraph Conf, pp. 27-34, ACM Press, 1997.

....polyps sized from 5 to 10 mm in diameter. Camera colonoscopy requires intravenous sedation to ease the discomfort. Consequently, many of those eligible for screening avoid the examination [7] In the past few years, virtual colonoscopy ( colonography ) has been developed as a modern alternative [8]. Generally, the procedure comprises of the following steps. First, the patient s colon is cleansed and distended by transanal inflation with air. Subsequently, a 3D image volume is acquired of the abdomen by CT or MRI. Finally, the interior bowel surface is extracted and visualized, after which ....

L. Hong, S.Muraki, A. Kaufman, T. He, `Virtual voyage: interactive navigation in the human colon', Proc. ACM SIGGRAPH Conf., pp. 27-34, ACM Press, 1997.

....degree of risk for the patient. In some diagnostic procedures, virtual endoscopy has the potential to be used in clinical routine to avoid the inconvenience of a real endoscopy. Most of the developed techniques concentrate on simulating the results that would be obtained with a real endoscope [6, 11]. Although this can be useful in some cases, like in an intraoperative scenario, virtual endoscopy should not constrain itself to simulate email:fanna,koenig,meisterg cg.tuwien.ac.at, http: www.cg.tuwien.ac.at email:frainer.wegenkittlg tiani.com, http: www.tiani.com the results of a ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings, Annual Conference series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....10 10 8 set of voxels, as shown in Figure 2(b) Viewpoints below the terrain surface are treated as having a completely occluded view of the world. Our second test scene consists of a set of winding tunnels, as shown in Figure 3. This dataset was motivated by applications such as colonoscopy [11]. The voxelization is constructed procedurally from the boundary representation of the tunnels. The viewpoint cell which contains a given viewpoint can be quickly located by computing a unique voxel ID based on the quantized xyz coordinates of the viewpoint, and then using a hash table indexed by ....

Lichan Hong, Shigeru Muraki, Arie Kaufman, Dirk Bartz, and Taosong He. Virtual voyage: Interactive navigation in the human colon. In Turner Whitted, editor, SIGGRAPH 97 Conference Proceedings, Annual Conference Series, pages 2734. ACM SIGGRAPH, Addison Wesley, August 1997.

....to compute information similar to that in [28] One can think of cPLP s obscured front as a single occluder, which has a few holes. If we think of the holes as portals , this is in certain respects analogous to the work of Luebke and Georges. In the context of their colonoscopy work, Hong et al. [15] propose a technique which merges Luebke and Georges s portals with a depth buffer based technique similar to ours. However, in their work, they exploit the special properties of the colon being a tube like structure. HyperZ [21] is an interesting hardware feature that has been implemented by ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. Proceedings of SIGGRAPH 97, pages 27--34, 1997.

....occluder are rendered into an auxiliary buffer called the cull map. Each pixel in the cull map (image space) corresponds to a grid cell of the scene grid (object space) If the cull map pixel is not covered then objects in the corresponding scene grid cell are potentially visible. Hong et al. [38] use an image based portal technique (similar in some respects to the cells and portals work of Luebke and Georges [48] to be able to fly through a virtual human colon in real time. The colon is partitioned into cells at preprocessing and these are used to accelerate the occlusion with the help ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In Turner Whitted, editor, SIGGRAPH 97 Conference Proceedings, Annual Conference Series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....techniques. Virtual endoscopy has the potential of becoming a substitute of real endoscopy for diagnostic procedures. A real endoscopy is invasive and, furthermore, involves a certain degree of risk for the patient. Most of the virtual endoscopy techniques presented in the last years [1 3] concentrate on simulating the view of a real endoscope. This is the view that the endoscopists are used to. It can be useful for certain applications, like in an intraoperative scenario, but it is not necessarily the best way to inspect the inner surface of an organ. Actually, a real endoscope ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings, Annual Conference series, pages 27-34. ACM SIGGRAPH, Addison Wesley, August 1997.

....used. CR Categories: I.3.3 [Computer Graphics] Picture Image Generation Display Algorithms; J. 3 [Life and Medical Sciences] Medical Information Systems ; Keywords: medical visualization, virtual endoscopy, visualization system 1 Introduction In recent years the usage of virtual endoscopy [7] [11] 12] has been extensively discussed. Virtual endoscopy allows an inner view of hollow structures by placing a virtual camera inside a three dimensional data volume most commonly produced by computer tomography (CT) or magnetic resonance tomography (MR) The advantages of this method are ....

....or occlusion culling [1] has to be used. Unfortunately occlusion culling is not appropriate when transparent surfaces are needed to show extra luminal vessels. In contrast, volume rendering techniques at interactive speed always lack visual quality, general acceptability or flexibility [5] [7]. Standard acceleration techniques for volume rendering are shear warp factorization [8] three dimensional texture mapping [2] 4] and distance leaping techniques [13] In many non medical fields of visualization image based rendering techniques have been successfully used to accelerate ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings, Annual Conference series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....of those surfaces which correspond to very thin specimens, such as blood vessels or other internal small cavities. This may improve either the measures taken on the extracted mesh (e.g. to evaluate the occurrence of stenosis or aneurysms in the vessel [29] or the quality of virtual navigation [14]. The presented solution might lead to a rapid growth of the surface size (number of faces) For most applications this is correct because the user needs to obtain a precise and smooth isosurface. When the number of triangles becomes a critical issue, a possible solution is to speedup rendering ....

Lichan Hong, Shigeru Muraki, Arie Kaufman, Dirk Bartz, and Taosong He. Virtual voyage: Interactive navigation in the human colon. In Turner Whitted, editor, SIGGRAPH 97 Conference Proceedings, Annual Conference Series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....Random 2.18 7.75 8.20 8.62 9.15 9.84 Cell Wise All 19.95 30.31 31.58 32.52 33.62 35.05 Skin 6. 70 10.13 10.75 11.32 12.10 13.02 Figure 6: Experimental Results on Voxel Reconstruction Time tem, based on direct volume rendering, will complement the polygon based navigation systems, for example, [7]. Acknowledgements The authors wish to thank Mr. Gee Bum Koo for his efforts to prepare our experiments. This work was supported in part by grants from Minstry of Science and Technology of Korea, and Korea Science and Engineering Foundation (KOSEF: 981 0926 138 1) ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and Taosong He. Virtual voyage: interactive navigation in the human colon. In Proceedings of ACM SIGGRAPH '97, pages 27--34, Los Angeles, August 1997.

....computer visualization techniques. Its fields of application, amongst others, are diagnosis avoiding the risks associated with a real endoscopy, training, and exploration of organs that cannot be reached with a real endoscope. Several virtual endoscopy systems have been proposed in recent years [5, 15, 18]. These systems are concerned with navigation inside the volume data and therefore with fast volume rendering. A virtual endoscopy system has mainly the following components: segmentation of the organ, user interaction, and rendering. email:fanna,meister,koenigg cg.tuwien.ac.at, ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings, Annual Conference series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....planning, training and exploration of structures not reachable with a real endoscope. All these fields have similar requirements concerning the visualization system : accuracy, intuitive interaction, fast visualization, and short preprocessing. Several virtual endoscopy systems have been proposed [5, 11, 12]. These systems are basically concerned with two visualization techniques: surface rendering and direct volume rendering. Surface rendering leads to a reduction of the data information from 3D (volume) to 2D (surfaces) This incurs a loss of information and accuracy while requiring surface ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings, Annual Conference series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997.

....94, I 09010 Uta (CA) Italy, http: www.crs4.it vvr conditions while avoiding worst case assumptions. Recently, a number of efficient adaptive algorithms have been introduced that incrementally adapt the rendering complexity of large scale surfaces (e. g terrains [2, 13] or large organic surfaces [10]) Many types of graphics scenes, however, often contain a large number of distinct and possibly animated small scale objects (e.g. rigid body simulations, virtual engineering prototypes [22] The traditional approach to render these scenes in a time critical setting is to pre compute a small ....

HONG, L., MURAKI, S., KAUFMAN, A., BARTZ, D., AND HE, T. Virtual voyage: Interactive navigation in the human colon. In SIGGRAPH 97 Conference Proceedings (Aug. 1997), T. Whitted, Ed., Annual Conference Series, ACM SIGGRAPH, Addison Wesley, pp. 27--34. ISBN 0-89791-896-7.

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, T. He, "Virtual voyage: Interactive navigation in the human colon," Computer Graphics Proceedings, Ann. Conf. Series, pp. 27-34, 1997

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. "Virtual Voyage: Interactive Navigation in the Human Colon". Proc. SIGGRAPH '97, 1997, 27-34.

....very efficiently and they can be used to approximate perspective rendering with parallel projection, so that our system can benefit from fast parallel projection hardware and algorithms. We use image warping to reduce the artifacts due to the approximation. 1 Introduction Virtual colonoscopy [14, 9] is a non invasive alternative to optical colonoscopy. The system takes a spiral CT scan of the patient s abdomen after the entire colon is cleansed. Several hundred high resolution CT images are rapidly acquired during a single breathhold of about 30 40 seconds, forming a volumetric abdomen data ....

....One trend of acceleration techniques is the so called indirect volume rendering, that transform the volume into an intermediate format, such as iso surface meshes. Surfacebased virtual colonoscopy system providing near real time exploration has been developed based on high end graphics hardware [9]. However, it is shown that direct volume rendering technique provides more realistic colonic images, flexible visualization of interior structures for polyps and other abnormalities, and shorter preprocessing time [26, 24] During the last decade, many acceleration methods for direct volume ....

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Lichan Hong, Shigeru Muraki, Arie Kaufman, Dirk Bartz, and Taosong He. Virtual voyage: Interactive navigation in the human colon. Proceedings of SIGGRAPH 97, pages 27--34, August 1997.

....testing stage, in which it is used for pre surgical planning of the actual intervention. Furthermore, it can be used for size measurements of anatomic features and for the volumetric assessment of cavities. In this context, it already has been successfully applied to patient datasets of the colon [7], ventricular system of the brain [3, 6] the vascular systems of the heart [1] and central nervous system [4] Techniques and systems of intra operative navigation are already used in the departments of neurosurgery [5, 6] and oral and maxillofacial surgery [8] Based on a preoperative acquired ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Computer Graphics (Proc. of ACM SIGGRAPH), pages 27-- 34, 1997.

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He, "Virtual Voyage: Interactive Navigation in the Human Colon," in Proc. SIGGRAPH, pp. 27--34, 1997.

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He, "Virtual Voyage: Interactive Navigation in the Human Colon," in Proc. SIGGRAPH, pp. 27--34, 1997.

....people do not follow this procedure because of the associated risk, discomfort, and high cost. In order to dramatically increase the number of people willing to participate in screening programs, we have been making efforts towards a computer based screening modality, called 3D virtual colonoscopy [1,2], as an alternative to optical colonoscopy, by employing advanced computer graphics and visualization techniques. In order to further improve the diagnostic accuracy of our virtual colonoscopy system, we propose electronic biopsy, an on line interactive diagnosis tool, which helps the physician to ....

.... a preprocessing stage [4,5] The virtual colon can then be viewed either by automatic planned navigation following the center line of the lumen of the colon, providing a general overview of the inner colonic surface [1] or by interactive navigation for a more detailed study of suspicious regions [2]. In our previous work, we developed this virtual colonoscopy system on a high end 16 processor SGI Power Challenger [6] and successfully ported it onto low cost PCs (Personal Computers) 7] with the world s first commercial real time volume rendering accelerator, called VolumePro, which was ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He, "Virtual Voyage: Interactive Navigation in the Human Colon",

....and flood fill techniques with two new techniques, namely, segmentation rays and volumetric contrast enhancement. flsarang, mwan, mie, arig cs.sunysb.edu We explain our segmentation algorithm using an example application of an upcoming virtual screening technique, Virtual Colonoscopy [3][4][9] which is being developed at the State University of New York (SUNY) at Stony Brook. We now briefly outline the segmentation requirements of the virtual colonoscopy system and previous solutions before explaning our solution using our new method. 2 The Experiment The aim of virtual ....

....and high density materials (which include the bone) A CT scan assigns different intensities to these materials and we classify them based on these intensities. For a physically cleansed colon, thresholding would be enough to accurately segment the colon for rendering in virtual colonoscopy [3][4]. However, with the new bowel preparation scheme, bones are not the only high density material present in the abdomen. Residual fluid and stool, which are enhanced with barium, also have CT image intensities similar to those of bone, thus complicating the segmentation. Although thresholding gives ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, T. He, Virtual Voyage: Interactive Navigation in the Human Colon, Proc. SIGGRAPH '97, pp. 27--34, 1997.

....Computer Graphics Group, Email: gordon.mueller tu bs.de 1.1 Related Work Several previous papers on visibility and occlusion culling touch the topic of scene organization. Generally, we observed that decomposition schemes for arbitrary polygonal models are difficult to derive. Hong et al. [13] used a technique which decomposes a CT based colon volume dataset al..ong its skeleton. The size of the different decomposition entities depends on how many voxels belong to this entity. While this scheme produced good results for a tube like colon model, it is not efficient for general models. ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He, "Virtual Voyage: Interactive Navigation in the Human Colon," Proc. ACM SIGGRAPH '97, pp. 2734, Aug. 1997.

....used techniques in Section 3. In Section 4, we discuss the learned lessons and finally, we summarize our paper in Section 5. 2 Related Work Research on virtual endoscopy is one of the most active areas in virtual medicine. The developed methods have been applied to virtual colonoscopy [10, 16], bronchoscopy [7] ventriculoscopy [1, 3] and angioscopy [6, 5, 8, 4] Different rendering techniques are used to provide sufficient visual quality and or interactivity. Standard graphics hardware is used to render surface models [17, 12, 10, 2] extracted with the Marching Cubes algorithm ....

....methods have been applied to virtual colonoscopy [10, 16] bronchoscopy [7] ventriculoscopy [1, 3] and angioscopy [6, 5, 8, 4] Different rendering techniques are used to provide sufficient visual quality and or interactivity. Standard graphics hardware is used to render surface models [17, 12, 10, 2], extracted with the Marching Cubes algorithm [11] In contrast, volume rendering techniques are used, partially for better visual quality, partially for interactive speed [15, 20, 8, 1] Unfortunately, interactive speed was always compromising visual quality, general applicability, or ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

....2 and present some results in Section 3. Finally, we conclude in Section 4. 2 Haptic Navigation Two major components are determining the navigation framework; a simulated current from a specified starting voxel to a specified target voxel, and the distance to the surface boundary of the cavity [5]. The methods were tested on a variety of convex and nonconvex voxel based objects and are generally applicable to a wide range of voxel based objects. In our example, we use a segment of an arterial blood vessel, derived from rotational angiography [2] The blood vessels are differentiated from ....

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Computer Graphics (Proc. of ACM SIGGRAPH), pages 27--34, 1997.

.... of automatic generation of the camera path were investigated by Vining et al. 18] Lorensen et al. 11] and Hong [6] In contrast, Rubin et al. manually specify a key frame interpolated camera path [14] Hong et al. proposed a new navigation method, implementing the guided navigation paradigms [7]. By combining distance fields and kinematic rules, an intuitive scheme for navigating inside the human colon was developed. Furthermore, a customized visibility algorithm was proposed in order to reduce the number of surface polygons of the inner surface of the colon to a feasible size. While ....

....endoscopy system to improve the planning of and orientation during this procedure. 4 VIVENDI Virtual Ventricle Endoscopy In this Section, we discuss the elements of the VIVENDI system for virtual ventricle endoscopy. In some parts, VIVENDI follows the VICON system for interactive colonoscopy [7]. However, due to the different anatomical topology, we use a different subdivision and visibility scheme. Therefore, the only common method is the guidednavigation system, which is already discussed in detail in [7] 4.1 System Architecture The endoscopy system itself consist of two stages: ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

....be hidden behind less important information. Two techniques are applied to solve this situation. The application of virtual clips limits the segmentation of the vessel tree to the part of the vessels the neuroradiologist is interested in. The second technique applies methods from virtual endoscopy [2, 8] to generate an interactive environment for the vascular examination from a point of view which is inside the vessels. We present the virtual angioscopy system in Section 3. Specifically, we briefly outline virtual clips in Section 3.1 and the virtual endoscopy system used for virtual angioscopy ....

....we conclude the paper in Section 5. # Email:fbartz,strasserg gris.uni tuebingen.de y Email: fmartin.skalej,dawelteg med.uni tuebingen.de 2 Related Work Research on virtual endoscopy is one of the most active areas in virtual medicine. The developed methods were applied to virtual colonoscopy [8, 15], bronchoscopy [6] ventriculoscopy [1, 3] and angioscopy [5, 4, 7] Different rendering techniques are used to provide sufficient visual quality and or interactivity. Standard graphics hardware is used to render surface models [16, 11, 8, 2] extracted with the Marching Cubes algorithm [10] In ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

....are known to solve these visibility problems, including the z buffer approach [7] the painter algorithm [13] and many more. Recently, visibility and occlusion culling have been of special interest for walkthroughs of architectural scenes [1, 36, 27] and rendering of large polygonal models [23, 15]. Unfortunately, these approaches are limited to cave like scenes [23, 38] or require special hardware support [21] In this paper, we present an algorithm for general visibility queries. This algorithm exploits several OpenGL features in order to obtain faster results for large polygonal ....

....approach [7] the painter algorithm [13] and many more. Recently, visibility and occlusion culling have been of special interest for walkthroughs of architectural scenes [1, 36, 27] and rendering of large polygonal models [23, 15] Unfortunately, these approaches are limited to cave like scenes [23, 38], or require special hardware support [21] In this paper, we present an algorithm for general visibility queries. This algorithm exploits several OpenGL features in order to obtain faster results for large polygonal models. To show the applicability of our algorithm in terms of graphics ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

....behind the less important information. Two techniques are applied to solve this situation. The application of virtual clips limits the segmentation of the vessel tree to the part of the vessels the neuroradiologist is interested in. The second technique applies methods from virtual endoscopy [2,7] to generate an interactive environment for the vascular examination from a point of view which is inside the vessels. In this paper, we briefly outline virtual clips in Section 2 and present the virtual endoscopy system used for virtual angiography in Section 3. In Section 4, we will present our ....

....Figure 2. If the area on the surface of the balloon inside the vessel is partitioned into two segments, the vessel is blocked. 3. Virtual Endoscopy Research on virtual endoscopy is one of the most active areas in virtual medicine. The developed methods were applied to virtual colonoscopy [7,9], bronchoscopy [5] ventriculoscopy [1,2] and angiography [4,3,6] However many systems either lack flexibility or interactivity which is necessary to apply the methods in daily routine. Based on the pre segmented image stack from rotation angiography, a polygonal representation of the ....

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

....A large variety of algorithms are known to solve these visibility problems, including the z buffer approach [3] the painter algorithm [7] and many more. Recently, visibility has been of special interest for walkthroughs of architectural scenes [1, 22, 18] and rendering of large polygonal models [16, 9]. Unfortunately, these approaches are limited to cavelike scenes [16, 23] or require special hardware support [14] In this paper, we present an algorithm for general visibility queries. This algorithm exploits several OpenGL features in order to obtain faster results for large polygonal models. ....

....including the z buffer approach [3] the painter algorithm [7] and many more. Recently, visibility has been of special interest for walkthroughs of architectural scenes [1, 22, 18] and rendering of large polygonal models [16, 9] Unfortunately, these approaches are limited to cavelike scenes [16, 23], or require special hardware support [14] In this paper, we present an algorithm for general visibility queries. This algorithm exploits several OpenGL features in order to obtain faster results for large polygonal models. To show the applicability of our algorithm even on low end graphics ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In Proc. of ACM SIGGRAPH, pages 27--34, 1997.

.... could also improve the diagnostic sensitivity and be used to explore body regions not accessible to conventional endoscopy [17] 13] To realize these significant promises of virtual endoscopy, many prototype systems have been developed for a variety of clinical applications, including colonoscopy[8], bronchoscopy[16] angioscopy[5] and others. As a crucial component of these systems, the navigation technique decides how the physician controls the position and orientation of a virtual camera to examine the inner surface of the organ. Earlier work [11] 6] 14] has focused on planned navigation ....

....is possible. By taking advantage of the rapid improvement and proliferation of graphics hardware, continuous navigation requires a physician to interactively control the camera positions and orientations at each frame and generate the resulting scene in real time [5] More recent work [7][8] has adopted the guided navigation scheme [3] to achieve more flexible visualization by combining the interactive camera manipulation and a guiding fly through path automatically generated by a navigation planner. With a guided navigation, the camera automatically moves from a source point to a ....

[Article contains additional citation context not shown here]

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In ACM SIGGRAPH, pages 27--34, 1997.

No context found.

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T.He.Virtual voyage: Interactive navigation in the human colon. In Proc. of 24th Annual Conf. on Computer Graphics and Interactive Techniques, Los Angeles CA, Aug 3-8 1997.

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. In Proc. of SIGGRAPH'97, 1997.

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L. Hong, S. Muraki, A. E. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactive navigation in the human colon. In Proceedings of SIGGRAPH 97, Computer Graphics Proceedings, Annual Conference Series, pages 27--34, Aug. 1997.

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L. Hong, S. Muraki., A. Kaufman, D. Bartz, and T. He. Virtual Voyage: Interactive Navigation in the Human Colon. SIGGRAPH 1997.

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L. Hong, S. Muraki, A. Kaufmann, D. Bartz, and T. He, \Virtual voyage: Interactive navigation in the human colon," in Proc. of ACM Siggraph, pp. 27-34, 1997.

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L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: interactive navigation in the human colon. In SIGGRAPH'97. International Conference on Computer Graphics and Interactive Techniques. Proceedings of the 24th annual conference on Computer graphics \& interactive techniques, pages 27--34, Los Angeles, CA USA, August 3--8, 1997. ACM.

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L. Hong, S. Muraki, A. Kaufmann, D. Bartz, and T. He, "Virtual voyage: Interactive navigation in the human colon", in Proc. of ACM Siggraph, pp. 27--34, (1997).

No context found.

Lichan Hong, Shigeru Muraki, Arie Kaufman, Dirk Bartz, and Taosong He. Virtual voyage: Interactive navigation in the human colon. Proceedings of SIGGRAPH 97, pages 27--34, August 1997. ISBN 0-89791-896-7. Held in Los Angeles, California.

No context found.

Lichan Hong, Shigeru Muraki, Arie Kaufman, Dirk Bartz, and Taosong He. Virtual voyage: Interactive navigation in the human colon. In Turner Whitted, editor, SIGGRAPH 97 Conference Proceedings, Annual Conference Series, pages 27--34. ACM SIGGRAPH, Addison Wesley, August 1997. ISBN 0-89791-896-7.

No context found.

L. Hong, S. Muraki, A. Kaufman, D. Bartz, and T. He. Virtual voyage: Interactivenavigation in the human colon. In SIGGRAPH 97 ConferenceProceedings, pages 27#34.

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