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Topic: Geometric primitives

	RenderMan - Developers Corner - Geometric Primatives
		On parametric primitives (quadrics and patches), varying primitive variables are bilinearly interpolated across the surface of the primitive.
		Primitive variables which are declared to be of type point (including the three predefined position variables) are specified in object space, and will be transformed by the current transformation matrix.
		The geometric normal of the polygon is computed by computing the normal of the plane containing the polygon (unless it is explicitly specified).
	renderman.pixar.com /products/rispec/rispec_3_1/section5.html (5274 words)

	2A) Ray tracing primitives
		A primitive is a shape for which a ray-shape intersection routine has been written.
		The sphere is the simplest finite object with which to intersect a ray.
		The disc is not a common ray tracing primitive, but is necessary in ray tracers which implement cones and cylinders without end caps.
	www.cl.cam.ac.uk /Teaching/2000/AGraphHCI/AG/p2a.html (1039 words)

	December 96 - New QuickDraw 3D Geometries (Site not responding. Last check: 2007-10-22)
		One category of geometric primitives is conics, quadrics, and quartics; this class includes such shapes as ellipses, disks, ellipsoids (the generalization of spheres), cones, cylinders, and tori (doughnuts).
		Geometric editing operations on the trimesh are similar to those on the polyhedron in immediate mode: you simply alter the point's position in the array in the data structure and rerender.
		This polyhedral primitive is the primitive of choice for the vast majority of programming situations and for the creation and distribution of model files if editing of models is desired.
	www.mactech.com /articles/develop/issue_28/schneider.html (8599 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		The boundary of a geometric object in a geometric complex is a subcomplex of that complex.
		Logically and structurally, topological objects and geometric objects could share the same subclass structure, but since there is a categorical homomorphism between the two that preserves boundary operations in each, this approach can cause confusion between the boundary of a topological object and the boundary of the corresponding geometric object.
		The primitives in this algebra are the TP_Primitives.
	www.omg.org /docs/transprt/98-09-01.txt (12660 words)

	Robust Geometric Primitives (Site not responding. Last check: 2007-10-22)
		Discussion: Implementing basic geometric primitives is a task fraught with peril, even for such simple tasks as returning the intersection point of two lines.
		If you are new to implementing geometric algorithms, I suggest that you study O'Rourke's Computational Geometry in C [O'R94] for practical advice and complete implementations of basic geometric algorithms and data structures.
		These primitives were implemented primarily for exposition rather than production use, but they should be quite reliable and might be more appropriate than LEDA for small applications.
	www2.toki.or.id /book/AlgDesignManual/BOOK/BOOK4/NODE184.HTM (1450 words)

	2D computer graphics -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-22)
		These components can be modified and manipulated by two-dimensional geometric transformations such as (A written communication in a second language having the same meaning as the written communication in a first language) translation, (The act of rotating as if on an axis) rotation, (Ascent by or as if by a ladder) scaling.
		Layers that consist of complex geometric objects (such as (The words of something written) text or polylines) may be broken down into simpler elements ((A written symbol that is used to represent speech) characters or line segments, respectively), which are then painted as separate layers, in some order.
		Therefore, any geometric primitives that are provided by the editor are immediately converted to pixels and painted onto the canvas.
	www.absoluteastronomy.com /encyclopedia/2/2d/2d_computer_graphics1.htm (1808 words)

	Tutorial # 5: Geometric Polygon Primitives
		The main disadvantage to using this primitive is memory usage: all data sent to the renderer with this primitive is copied and stored in internal data arrays; this can potentially double the amount of memory used by your application if you do not free up the original data passed to the renderer.
		This primitive is not recommended for large numbers of polygons since the command must be called for each and every polygon; also, the polygons are not stored very efficiently within the renderer as compared to the other two primitives.
		This primitive is quite different from the previous two primitives described because the data is requested from the host application only at the moment it is to be rendered.
	www.okino.com /new/toolkit/tut/main12.htm (2547 words)

	3DELIGHT User's Manual: 4.2 Attributes (Site not responding. Last check: 2007-10-22)
		Attributes are components of the graphic state that are associated with elements of the scene, such as geometric primitives and light sources.
		Primitives that are in the same subsurface group are considered as forming one closed object.
		Whenever a displacement shader is applied to a primitive, one must specify a displacement bound to inform the renderer about maximum displacement amplitude.
	www.3delight.com /Zdoc/3delight_20.html (1179 words)

	Geometric Analysis, Visualization, and Conceptualization of 3D Image Data
		By "geometric" model we mean a collection of geometric primitives (points, lines, polygons, etc.) that accurately represent the shape of the surface.
		These geometric descriptions are used to enhance the visualization of the object and to provide for quantitative analysis (the surface area, volume, mean curvature, topology, etc.).
		This mesh of small polygons is now a "geometric" definition of the surface of the structure of interest.
	froggy.lbl.gov /papers/Reports/LBL.35329.html (1216 words)

	Geometric Primitives
		Each primitive, along with the command used to generate it and the parameters associated with it, are described next.
		Primitives are created and given an ID equal to one plus the current highest body ID in the model.
		Primitive solids are created with their centroid at the origin or the world coordinate system.
	cubit.sandia.gov /help-version7/Chapter_4/Geometry_Creation/Geometric_Primitives.html (200 words)

	RenderMan - Developers Corner - Relationship To The Renderman Interface
		All geometric primitives use the current surface shader for computing the surface shading at their surfaces and the current exterior shader for computing the attenuation of light through the volume containing them.
		Solid primitives define an interior volume; the optical properties of this volume are described by the current interior shader.
		Finally, when a geometric primitive is being shaded, the shaders associated with it are executed.
	renderman.pixar.com /products/rispec/rispec_3_1/section10.html (742 words)

	WebWorlds: The Toolbar and Primitives - Primitives
		Primitives are the basic building blocks of 3D design.
		Geometric primitives are the Plane, Cube, Cylinder, Cone, Sphere and Torus.
		Each of the available six primitives has a property panel that is accessible by right-clicking on the icon of the primitive.
	www.msu.edu /~ionescua/pioneer/cpwk2_1c.htm (821 words)

	3DELIGHT User's Manual: 4.3 Geometric Primitives (Site not responding. Last check: 2007-10-22)
		The default mode is to render points using a lightweight primitive, suitable for clouds of tiny particles (such as clouds of dust, stars, etc...).
		When a procedural primitive contains a motion block, it is the user's responsability to take it into account when providing the renderer with a bounding box for the procedural primitive.
		It is therefore necessary to declare the required elements before the procedural primitives that require them and not to replace them until after the end of world block, when rendering is complete.
	www.3delight.com /Zdoc/3delight_21.html (819 words)

	Geometric versus Volumetric 3D Models (Site not responding. Last check: 2007-10-22)
		The quality and applicability of geometric 3D morphing techniques [12] is highly dependent on the models' geometric primitives and their topological properties.
		Volume morphing may be applied to objects represented either by geometric primitives or by volumes.
		Geometric descriptions can be easily converted to high-quality volume representations, as we will see in section 2.
	graphics.stanford.edu /papers/morph/paper/node3.html (168 words)

	ECS EPrints Service - Primitive Extraction via Gathering Evidence of Global Parameterised Models (Site not responding. Last check: 2007-10-22)
		The extraction of geometric primitives from images is a fundamental task in computer vision.
		The Hough transform is an established technique for extracting geometric shapes based on the duality definition of the points on a curve and their parameters.
		This technique has been developed for extracting simple geometric shapes such as lines, circles and ellipses as well as arbitrary shapes represented in a non-analytically tabular form.
	eprints.ecs.soton.ac.uk /archive/00000023 (400 words)

	Algorithms for the VisionArchitecture
		The easiest way to calculate the intersection of a geometric object with a Range object or the containment of an object within a Range object is for a primitive to simply obtain a Range object of itself and execute the intersection or containment method for two Range objects.
		Each geometric primitive is capable of generating a subdivision of itself, and returning it in a master subdivision object.
		All geometric objects in the scene are requested to return a Subdivision object of themselves (step 2 in Figure 6.13), constrained to be a polygonal approximation.
	graphics.cs.uni-sb.de /~slusallek/Doc/html/node11.html (17776 words)

	ipedia.com: 2D computer graphics Article (Site not responding. Last check: 2007-10-22)
		2D graphics models may combine geometric modelss (also called vector graphics), digital images (also called raster graphics), text to be typeset (defined by content, font style and size, color, position, and orientation), mathematical functionss and equations, and more.
		Layers that consist of complex geometric objects (such as text or polylines) may be broken down into simpler elements (characters or line segments, respectively), which are then painted as separate layers, in some order.
		These editors generally output graphics files where the layers and primitives are separately preserved in their original form.
	www.ipedia.com /2d_computer_graphics.html (1482 words)

	Common Geometric Primitives (Site not responding. Last check: 2007-10-22)
		Like most computer terms, “geometric primitive” is just a big name for something so simple that it can be identified by almost any child.
		We thought we were just playing and having fun, but my mother somehow knew we were really mastering the fine art of modeling with geometric primitives.
		Geometric primitives are the basic shapes we all know and recognize.
	www.gamescapers.com /Pages/C4P1.htm (234 words)

	Abstract: Locating geometric primitives (Site not responding. Last check: 2007-10-22)
		This paper examines the detection of geometric primitives using 2d edge pixels or 3d range points.
		An explicit error model allows the primitives to be extracted robustly, while a hierarchical search of the parameter space with conservative pruning allows the primitives to be located efficiently.
		The result is an efficient search strategy that is robust to distractors, missing data and noise, and that does not require an initial estimate of the positions of the geometric primitives.
	faculty.washington.edu /cfolson/abstracts/pr2001.html (124 words)

	DIMACS Workshop on Implementation of Geometric Algorithms
		One is the difficulty to implement the geometric primitives, which get more complicated as the algorithms get more complex.
		Geometric conditioning is a third approach: modify the input coordinates so that every necessary numerical calculation is well-conditioned.
		More generally, geometric conditioning can be thought of as an optimization problem: find the minimum (least-squares) perturbation of the coordinates that leads to a well-conditioned output.
	dimacs.rutgers.edu /Workshops/GeomAlgorithms/abstracts.html (4039 words)

	Seek 'Geometric' related info here. (Site not responding. Last check: 2007-10-22)
		The question of geometric construction with the compass alone is not concerned with such kinds of geometries.
		Geometric Modeling and Processing 2000 (Theory and Applications) The Council Chamber, Floor 8, Meng-Wah Complex Hong Kong April 10-12, 2000.
		The typeface is Geometric Slabserif 703, which is Bitstream's version of Memphis a typeface designed in 1930 by Rudolph Weiss.
	netinfoseek.com /?q=geometric (740 words)

	Locating Geometric Primitives by Pruning the Parameter Space - Olson (ResearchIndex)
		Abstract: This paper examines the detection of geometric primitives using 2d edge pixels or 3d range points.
		The geometric primitives are described by parametric equations in the image space.
		An explicit error model allows the primitives to be extracted robustly, while a hierarchical search of the parameter space with conservative pruning allows the primitives to be located eciently.
	citeseer.ist.psu.edu /olson01locating.html (573 words)

	DCG Description
		Natural scenes are quite complex and demand a huge amount of geometric primitives to be modeled in sufficient detail for realistic rendering.
		With object instancing all four tires are represented by one and the same assembly of primitives, which are transformed to their correct position during rendering.
		Ray tracing is done by traversing the DCG until the rays are send to a geometric primitive object.
	www.cg.tuwien.ac.at /research/rendering/csg-graphs/Description.html (1704 words)

	2A) Ray tracing primitives
		If one wishes to use the curved primitives (sphere, cylinder, cone, torus, disc) with PSC then they must be converted to polygons.
		She could simply use the finite-length open cylinder primitive and two disc primitives.
		Alternatively she could implement the finite-length closed cylinder as a primitive in its own right by adding extra code to the open cylinder algorithm.
	www.cl.cam.ac.uk /Teaching/2003/AdvGraph/html/p2a.html (1319 words)

	Geometric Algebra: A Computational Framework for Geometrical Applications - Dorst, Mann (ResearchIndex) (Site not responding. Last check: 2007-10-22)
		Abstract: Geometric algebra is a consistent computational framework in which to define geometric primitives and their relationships.
		Since it contains primitives of any dimensionality (rather than just vectors) it has no special cases: all intersections of primitives are computed with one general incidence operator.
		...x in the (a, b) plane that is to c as the vector b is to a Geometric algebra phrases this as x c 1 = ba 1, and solves it as (see eq.
	citeseer.ist.psu.edu /448265.html (590 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		If you used the mouse, Alias orients the primitive so that the "top" of the primitive (or the "face" of the circle) points toward you in the window where you clicked.
		The default behavior of the primitive tools is to create a 1 unit wide (10 units for AutoStudio) primitive where you click.
		When you place or move an object in the perspective window while a construction plane is active, the object is automatically constrained to the construction plane.
	www.c3.hu /docs/alias9.0/Modeling/CreatingObjects.fm.html (1175 words)

	GridEx Documentation (Site not responding. Last check: 2007-10-22)
		This will typically involve the creation of one or more geometric primitives to define the enclosing domain of interest followed by a series of volume operations to incorporate the desired geometry model.
		Basic primitives consisting of a Box, Sphere, Cone, and Cylinder may be created to represent the domain's far-field boundary by simply providing the appropriate defining data in the appropriate dialog window.
		As for the other primitives, specification of the axis points must be unique and the radius must be greater than zero to provide a non-zero volume.
	geolab.larc.nasa.gov /GridEx/CADGeom.htm (846 words)

	Chapter 2 - OpenGL Programming Guide (Addison-Wesley Publishing Company)
		Whenever a particular geometric object is drawn, it's drawn using the currently specified coloring scheme.
		To draw geometric primitives that can be seen, however, you need some basic knowledge of how to set the current color; this information is provided in the next paragraphs.
		All geometric primitives are eventually described in terms of their vertices - coordinates that define the points themselves, the endpoints of line segments, or the corners of polygons.
	fly.srk.fer.hr /~unreal/theredbook/chapter02.html (9715 words)

	Drawing in Space: Geometric Primitives and Buffers in OpenGL (Site not responding. Last check: 2007-10-22)
		All primitives in OpenGL are one- or two-dimensional objects, ranging from single points to lines and complex polygons.
		This approach might seem backward, but if you first know how to draw something and then worry about all the ways to manipulate your drawings, the material in Chapter 4, "Geometric Transformations: The Pipeline," is more interesting and easier to learn.
		When you have a solid understanding of graphics primitives and coordinate transformations, you will be able to quickly master any 3D graphics language or API.
	www.quepublishing.com /articles/article.asp?p=328646 (547 words)

	Scan-Conversion of Geometric Primitives - CMPT 361: D. Hepting
		graphics package clips and scan converts the primitives to the pixels on the screen: specifies what is to be generated, how it is to be generated, where the image is to be generated, and how the image (frame buffer) is to be modified.
		Starting at edge of a clip rectangle: we must use the midpoint test result rather than computing intersections analytically if we are to ensure the correct sequence of pixels.
		Output primitives composed of lines: scan-converting boundaries as lines can lead to problems.
	www.cs.sfu.ca /~torsten/Teaching/Cmpt361/LectureNotes/HTML/06_2Dlines-OLD (809 words)

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