B. Naylor, "SCULPT: an interactive solid modeling tool", proc. Graphics Interface'90, pp. 138-148, 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....use. Fortune [12] introduces the use of floating point filters which combines the efficiency of floating point arithmetic and the robustness of exact arithmetic. We are unaware of any literature that describes the use of Fortune s floating point filter in interactive free form sculpting. Naylor [31][32] proposes yet another solid representation that uses BSP trees. The volumes enclosed in solids are bounded by sets of space partitioning planes. Boolean operations on these solids are applied by merging their BSP trees [30] The exterior surfaces of solids may be stored as polygonal faces with ....

Naylor, B., "SCULPT: An Interactive Solid Modeling Tool", Proceedings of Graphics Interface '90, pp. 138-148 (1990).

.... by Schumacker et al. 26] and further refined by Fuchs et al. 16] is a hierarchical partitioning of space widely used in several areas, including computer graphics (global illumination [7] shadow generation [10, 11] visibility determination [4, 28] and ray tracing [21] solid modeling [22, 20, 29], geometric data repair [19] robotics [5] network design [18] and surface simplification [3] Key to Support was provided by National Science Foundation research grant CCR 93 01259, by Army Research Office MURI grant DAAH04 96 1 0013, by a Sloan fellowship, by a National Science ....

B. F. Naylor, SCULPT: an interactive solid modeling tool, Proc. Graphics Interface '90, 1990, pp. 138--148.

....like edges and corners using C 0 or C 1 curved surfaces. These operations use a Ganith process as a back end. Refer to the Shastra section for more information. 2. 7 MENU BUTTON: BOOLEAN SET OPERATIONS This shell lets the user perform some boolean set operations on only polyhedral objects [14]. Here SHILP manipulates the topology of the polyehdron while individual Boolean set are done remotely using SCULPT processes (see the subsection on SHASTRA later in this manual) Potentially a separate SCULPT server (a polyhedral boolean operation back end) process can be invoked for each ....

B. Naylor. SCULPT : An interactive solid modeling tool. In Proc. of Graphics Interface, Halifax, Nova Scotia, May 1990. Graphics Interface '90.

....using a variation of the traditional Binary Space Partition (BSP) Trees. The BSP tree is a versatile structure commonly used for hidden surface removal and solid modeling [4,5,8] Other uses of the BSP Trees are in shadow generation, collision detection, implementing set operations on objects etc [3,4,5,6]. A BSP tree is a binary tree used to partition n dimensional space and essentially to sort polytopes. The tree taken as a whole represents the entire space, and each subtree represents a convex subspace. Each node stores a hyperplane which divides the space it represents into two parts, and has ....

Naylor, B., SCULPT An Interactive Solid Modeling Tool, Proceedings of Graphics Interface '90, 138--148, may 1990.

....technique to edit a model. Many sculpting systems use a volume representation [1, 15, 26] These systems suffer from artifacts caused by the discrete and regular subdivision, and permit interactive editing of fine details only at the expense of high memory requirements (512 Mb or more 2 ) BSP [23] and CSG [22] sculpting systems allow exact geometry modification and representation as opposed to the sampled approximation of volume sculpting. However, this advantage is also a drawback for repetitive modifications since 2 From promotional material of the FreeForm system by SensAble. the ....

....normals need to be recomputed. These must be consistent with both the original normals and the adaptive refinement incurred by the simulation. Information about the normals is extracted in a preprocess and appropriate normals are assigned before rendering. As in many other techniques (e.g. [15, 22, 23, 25]) we ignore the aging effects on the tool for simplicity. 5 This restriction is not severe, since in most cases we see the aging effects on the affected object (e.g. we see a scratch on the floor, but not the shoe that caused it) rather than the objects which cause the impacts (e.g. the mugs, ....

B. Naylor. SCULPT an interactive solid modeling tool. In Proceedings of Graphics Interface '90, pages 138--148, May 1990.

.... by Schumacker et al. 31] and further re ned by Fuchs et al. 18] is a hierarchical partitioning of space widely used in several areas, including computer graphics (global illumination [9] shadow generation [12, 13] visibility determination [4, 33] and ray tracing [24] solid modeling [27, 25, 34], geometric data repair [23] robotics [5] network design [21] and surface simpli cation [3] Key to the BSP s success is that it serves both as a model for an object (or a set of objects) and as a data structure for querying the object. Informally, a BSP B for a set of objects is a binary ....

B. F. Naylor, SCULPT: an interactive solid modeling tool, Proc. Graphics Interface '90, 1990, pp. 138-148.

....to a model simultaneously, in an intuitive fashion. Virtual tools have been used in a number of modeling systems, most typically as a method of defining boolean operations to be applied to solid and volumetric models. They are used in this way by Parent (whose polygonal models described solids) Naylor (1990), and Mingxian et al. (1993) and in a related way by Galyean [Par77, Nay90, GH91, MFD93] Mingxian uses CSG based virtual modeling tools in a non free form CAD system. Pushing and pulling points as we propose to do has been done to some extent by Brewer (1977) Hsu (1992) and Szeliski (1992) ....

....in a number of modeling systems, most typically as a method of defining boolean operations to be applied to solid and volumetric models. They are used in this way by Parent (whose polygonal models described solids) Naylor (1990) and Mingxian et al. (1993) and in a related way by Galyean [Par77, Nay90, GH91, MFD93] Mingxian uses CSG based virtual modeling tools in a non free form CAD system. Pushing and pulling points as we propose to do has been done to some extent by Brewer (1977) Hsu (1992) and Szeliski (1992) BA77, HHK92, ST92] Brewer pushed parametric surfaces control points with a ....

[Article contains additional citation context not shown here]

B. Naylor. Sculpt: an interactive solid modeling tool. Proceedings of Graphics Interface 1990, pages 138--148, May, 1990.

....the BSP ensures that a back to front order from any viewpoint can be determined for the fragments. BSPs have subsequently proven to be versatile, with applications in many problems apart from hiddensurface removal [8, 101] global illumination [23] shadow generation [29, 30] solid modelling [75, 78, 102], ray tracing [74] robotics [12] and approximation algorithms for network design [66] and surface simplification [7] The efficiency of our model repair and hidden surface removal algorithms algorithms as well as the applications mentioned above inherently depends on the size and height of the ....

....like spurious shadows in the result. Bad meshes can also produce errors in finite element analysis. Further, basic CAD CAM operations like computing the mass or volume of an object, solid modelling techniques such as Constructive Solid Geometry that perform set operations on solid objects [75, 78, 102], and rapid prototyping [94] which is used to manufacture objects from CAD designs, need models with continuous and closed boundaries, with no cracks or improper intersections. Finally, systems that design and optimise wireless communication systems for a closed environment like a building ....

[Article contains additional citation context not shown here]

B. F. Naylor, SCULPT: an interactive solid modeling tool, Proc. Graphics Interface '90, 1990, pp. 138--148.

....like edges and corners using C 0 or C 1 curved surfaces. These operations use a Ganith process as a back end. Refer to the Shastra section for more information. 2. 7 MENU BUTTON: BOOLEAN SET OPERATIONS This shell lets the user perform some boolean set operations on only polyhedral objects [14]. Here SHILP manipulates the topology of the polyehdron while individual Boolean set are done remotely using SCULPT processes (see the subsection on SHASTRA later in this manual) Potentially a separate SCULPT server (a polyhedral boolean operation back end) process can be invoked for each ....

B. Naylor. SCULPT : An interactive solid modeling tool. In Proc. of Graphics Interface, Halifax, Nova Scotia, May 1990. Graphics Interface '90.

....to a model simultaneously, in an intuitive fashion. Virtual tools have been used in a number of modeling systems, most typically as a method of defining boolean operations to be applied to solid and volumetric models. They are used in this way by Parent (whose polygonal models described solids) Naylor (1990), and Mingxian et al. (1993) and in a related way by Galyean [Par77, Nay90, GH91, MFD93] Mingxian uses CSG based virtual modeling tools in a non free form CAD system. Pushing and pulling points as we propose to do has been done to some extent by Brewer (1977) Hsu (1992) and Szeliski (1992) ....

....in a number of modeling systems, most typically as a method of defining boolean operations to be applied to solid and volumetric models. They are used in this way by Parent (whose polygonal models described solids) Naylor (1990) and Mingxian et al. (1993) and in a related way by Galyean [Par77, Nay90, GH91, MFD93] Mingxian uses CSG based virtual modeling tools in a non free form CAD system. Pushing and pulling points as we propose to do has been done to some extent by Brewer (1977) Hsu (1992) and Szeliski (1992) BA77, HHK92, ST92] Brewer pushed parametric surfaces control points with a ....

B. Naylor. Sculpt: an interactive solid modeling tool. Proceedings of Graphics Interface 1990, pages 138--148, May, 1990.

....like edges and corners using C 0 or C 1 curved surfaces. These operations use a Ganith process as a back end. Refer to the Shastra section for more information. 2. 7 MENU BUTTON: BOOLEAN SET OPERATIONS This shell lets the user perform some boolean set operations on only polyhedral objects [14]. Here SHILP manipulates the topology of the polyehdron while individual Boolean set are done remotely using SCULPT processes (see the subsection on SHASTRA later in this manual) Potentially a separate SCULPT server (a polyhedral boolean operation back end) process can be invoked for each ....

B. Naylor. SCULPT : An interactive solid modeling tool. In Proc. of Graphics Interface, Halifax, Nova Scotia, May 1990. Graphics Interface '90.

....objects, the BSP ensures that a back to front order from any viewpoint can be determined for the fragments. BSPs have subsequently proven to be versatile, with applications in many other problems global illumination [6] shadow generation [10, 11] visibility problems [4, 30] solid modeling [23, 25, 31], geometric data repair [20] ray tracing [22] robotics [5] and approximation algorithms for network design [19] and surface simplification [3] Algorithms have also been developed to construct BSPs for moving objects [1, 12, 24, 32] Informally, a BSP B for a set of objects is a binary tree. ....

B. F. Naylor, SCULPT: an interactive solid modeling tool, Proc. Graphics Interface '90, 1990, pp. 138--148.

....like spurious shadows in the result. Bad meshes can also produce errors in finite element analysis. Further, basic CAD CAM operations like computing the mass or volume of an object, solid modeling techniques such as Constructive Solid Geometry that perform set operations on solid objects [18, 21, 28], and rapid prototyping [24] which is used to manufacture objects from CAD designs, need models with continuous and closed boundaries, with no cracks or improper intersections. Finally, systems that design and optimize wireless communication systems for a closed environment like a building ....

Bruce F. Naylor. SCULPT: an interactive solid modeling tool. In Proc. Graphics Interface '90, pages 138--148, 1990.

....or out [Thibault and Naylor 1987] The BSP tree has unique advantages as an intermediate representation for the different views. Its tree structure allows very efficient algorithms to be developed, it is compact, and it is numerically robust. Naylor has built a 3 D modeling system called SCULPT [Naylor 1990] which has as its underlying primitive descriptions of polyhedral objects as BSP trees. In graphics Chin and Feiner [Chin and Feiner1989 ] have analyzed shadow generation using BSP trees, and in image processing Radha et al. Radha et al. 1991] have used a BSP tree representation of a 2 D image ....

....form the nodes in the second tree. Polygons that end up at in leaves are contained by both polyhedra. Applying this to both trees and unioning the result will give us the space that is contained by both modeled objects. An analysis of the robustness and complexity of set operations is given in [Naylor et al. 1990] . To briefly restate here, merging two n node BSP trees provides a complexity which is worst case optimal Q(n 2 ) However, the expected case for two good (i.e. balanced) BSP trees is 0(n log n) Figure 2: A machined part. 4 Experimental Results and Conclusions We have implemented our ....

B. Naylor. SCULPT: An interactive solid modeling tool. In Graphics Interface, pages 138--148, May 1990.

....that fragments the objects and ensures that a back to front order from any viewpoint can be determined for the fragments. BSPs have proven to be versatile, with applications in many other problems global illumination [5] shadow generation [7, 8, 9] visibility problems [3, 25] solid geometry [19, 20, 26], geometric data repair [16] ray tracing [18] robotics [4] and approximation algorithms for network design [15] and surface simpli cation [2] Informally, a BSP B for a set of polygons in R 3 is a binary tree. Each node v of B is associated with a convex region R v . The regions associated ....

B. F. Naylor, SCULPT: an interactive solid modeling tool, Proc. Graphics Interface '90, May 1990, pp. 138148.

....algorithm, depends upon the size of the BSP. The BSP has subsequently proven to be a versatile data structure with applications in many other problems that arise in practice global illumination [5] shadow generation [7, 8, 9] ray tracing [19] visibility problems [3, 23] solid geometry [17, 18, 24], robotics [4] and approximation algorithms for network flows and surface simplification [2, 16] Although several simple heuristics have been developed for constructing BSPs of reasonable sizes [3, 13, 14, 23, 24] provable bounds were first obtained by Paterson and Yao. They show that a BSP of ....

B. Naylor. SCULPT an interactive solid modeling tool. In Proceedingsof Graphics Interface '90, pages 138--148, May 1990.

....of CSG models. This approach shows that BSP trees can also be used interactively in circumstances where the scene itself is changing for example, Thibault and Naylor describe an application where a tool is interactively added or subtracted from a work piece. This is described in detail in [21]. The issue of computing changes to BSP trees dynamically, caused by changing object geometry, is taken up in section 8. 3. Base Line Algorithm for Computing Shadows The crucial point of the BSP tree method is that the tree is constructed once and for all, and then for any viewpoint a unique ....

....a scene (for example, translating or rotating an object) a frequently used approach is to recompute and redisplay the entire scene. However, incremental changes can be expressed as sequences of polygon deletions 1 This was pointed out by a referee. 20 and additions. Some progress has been made [21][30] 31] in dynamically changing BSP trees for this purpose, but such work does not include a consideration of shadows. Recent work 1 shows that the ST approach can be efficiently used for dynamic modifications of objects in scenes represented as BSP trees, including correct changes to shadows. We ....

Naylor, B. (1990) SCULPT: An Interactive Solid Modeling Tool, Graphics Interface 90, Morgan-Kaufmann Publishers, 138-155

....of the tree. This ordering can be either far to near (back to front) or near tofar (front to back) Generating this ordering can be combined with view volume clipping, which performs a nondestructive intersection operation between the model and the view volume, generally in sub linear time [Naylor 90b] Regardless of the ordering, a partitioning tree representing the image can be generated by forming the union of the faces in priority order. More specifically, consider a near to far ordering with the initial value of the image being the empty set. 1) project each face onto the 2D projection ....

Bruce F. Naylor, "SCULPT: an Interactive Solid Modeling Tool," Proceeding of Graphics Interface (May 1990).

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Bruce Naylor. SCULPT an interactive solid modeling tool. In Proceedings of Graphics Interface '90, pages 138--148, May 1990.

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B. Naylor, "SCULPT: an interactive solid modeling tool", proc. Graphics Interface'90, pp. 138-148, 1990.

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B. Naylor. Sculpt: An interactive solid modeling tool. Proceedings of Graphics Interface'90, pages 138--148, 1990.

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B. Naylor, "SCULPT: an interactive solid modeling tool", proc. Graphics Interface'90, pp. 138-148, 1990.

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Naylor, B., SCULPT An Interactive Solid Modeling Tool, Proceedings of Graphics Interface '90, 138-148, may 1990.

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Naylor, B., SCULPT An Interactive Solid Modeling Tool, Proceedings of Graphics Interface '90, 138-148, may 1990.

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Naylor, B., SCULPT An Interactive Solid Modeling Tool, Proceedings of Graphics Interface '90, 138--148, may 1990.

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