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Topic: Gouraud shading

Related Topics

Flat shading

Phong shading

Ray tracing

Computer graphics

Hidden face removal

3D computer graphics

Global illumination

Radiosity

Bui tuong phong

Henri Gouraud

Bump mapping

Graphical output device

Raster graphics

Volume rendering

Texture mapping

	Gouraud shading - Wikipedia, the free encyclopedia
		Gouraud shaded sphere - note the inaccuracies towards the edges of the polygons.
		Gouraud shading is a method used in computer graphics to simulate the differing effects of light and colour across the surface of an object.
		Gouraud shading is much less processor intensive than Phong shading, but does not calculate all desirable lighting effects as accurately.
	en.wikipedia.org /wiki/Gouraud_shading (387 words)

	Phong shading - Wikipedia, the free encyclopedia
		The main problem with Gouraud shading is that when a specular highlight occurs near the center of a large triangle, it will usually be missed entirely.
		As in Gouraud shading, we linearly interpolate a normal N across the surface of the triangle, from the three given normals.
		This is done, as in Gouraud shading, for each pixel in the triangle, and at each pixel we normalize N and use it in the Phong illumination model to obtain the final pixel color.
	en.wikipedia.org /wiki/Phong_shading (555 words)

	Gouraud shading -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-07)
		Gouraud shading is a method used in (The pictorial representation and manipulation of data by a computer) computer graphics to simulate the differing effects of light and colour across the surface of an object.
		To complete the shading, the (An iconic mental representation) image is filled by lines drawn across the image that interpolate between the previously calculated edge intensities.
		Gouraud shading is much less processor intensive than (Click link for more info and facts about Phong shading) Phong shading, but does not calculate all desirable lighting effects as accurately.
	www.absoluteastronomy.com /encyclopedia/G/Go/Gouraud_shading.htm (465 words)

	[No title] (Site not responding. Last check: 2007-10-07)
		Flat shading is the roughest approximation of this, planes are rendered in a single color which is determined by the cosine of the angle between the plane's normal vector and the light vector.
		Gouraud shading is a linear interpolation of color between known intensities of light.
		With gouraud shading, specular highlights are gradated in a linear manner.
	www.flipcode.com /documents/otmphong.txt (2932 words)

	Computer Graphics : Illumination and Shading : 30 / 32 : Gouraud Shading
		The Gouraud Shading method applies the illumination model on a subset of surface points and interpolates the intensity of the remaining points on the surface.
		Gouraud shading actually first interpolates between vertices and assigns values along triangle edges, then it interpolates across the scan line based on the interpolated edge crossing values.
		The disadvantage to Gouraud is that its overall effect suffers on lower triangle-count models, because with fewer vertices, shading detail (specifically peaks and valleys in the intensity) is lost.
	escience.anu.edu.au /lecture/cg/Illumination/gouraudShading.en.html (467 words)

	Gouraud shading - Glossary - CNET.com (Site not responding. Last check: 2007-10-07)
		In 3D graphics, the polygons that make up the images need to be shaded; otherwise, you'd see a chicken-wire framework instead of a realistic landscape and structures.
		Gouraud shading is a complex process using algorithms to create a color gradient.
		This shading is acceptable for gaming worlds and is a solid criterion in benchmark quotes.
	www.cnet.com /Resources/Info/Glossary/Terms/gouraudshading.html (55 words)

	Gouraud Shading, Flat Shading, etc...
		Gouraud shading extends the concept of interpolated shading applied to individual polygons by interpolating polygon vertex illumination values that take into account the surface being approximated.
		The Gouraud shading process requires that the normal {perpendicular vector} be known for each vertex of the polygonal mesh.
		The term 'Gouraud shading' is often generalized to refer to intensity interpolation shading of even a single polygon in isolation, or to the interpolation of arbitrary colors associated with polygon vertices {as is the case in computer games}.
	www.futuretech.blinkenlights.nl /gouraud.html (2421 words)

	GameDev.net - Gouraud
		Gouraud shading Warning: some knowledge about vectors required Types of shading Shading is the change in saturation on a surface because of reflection.
		Shading depends on the properties of the surface and the angle between surface, light source and your eyes There are three types of shading which are commonly used in computer graphic programs.
		The object you are to shade is divided in a lot of flat surfaces.
	www.gamedev.net /reference/articles/article322.asp (651 words)

	Gouraud Shading - Wikipedia
		Das Gouraud Shading (auch als Intensitätsinterpolations-Shading oder Farbinterpolations-Shading bekannt) ist ein Verfahren in der 3D-Computergrafik, um Polygon-Flächen zu schattieren (engl.
		Beim Gouraud Shading werden zunächst die Farben des darzustellenden Polygons an seinen Eckpunkten (Vertizes) berechnet und die Vertizes auf die Bildebene projiziert.
		Das Gouraud Shading ist eines der schnellsten Verfahren in der 3D-Computergrafik zur Darstellung räumlicher Objekte.
	de.wikipedia.org /wiki/Gouraud_Shading (211 words)

	Basic Light Reflection Model
		Phong shading is more expensive than Gouraud shading and obeys the first law of computer graphics, which appears to be that the required processing time grows exponentially with perceived image quality.
		An obvious highlight example that Gouraud shading misses altogether is the case of a highlight in the middle of a polygon.
		The advantage of Gouraud shading is that it is computationally the less expensive of the two models, only requiring the evaluation of the intensity equation at the polygon vertices, and then bilinear interpolation of these values for each pixel.
	www-viz.tamu.edu /faculty/parke/ends489f01/notes/sec7_3.html (3934 words)

	nV News - Interpalotive Shading
		Interpolative Shading means that during the rendering process of a polygon, given specific information about a vertex (whether it be color intensity, or a normal) of that polygon, calculations are made between these vertices using a linear equation(s) to find the information about the pixel inside a polygon (or in-between a polygon edge).
		Gouraud calculates intensities at the polygon vertices only, using a local reflection model, and interpolates these pixels within the polygon.
		Notice if there were a specular highlight in the middle of a quad (or any polygon), Gouraud shading would miss it completely since it only has information about the intensities of the pixel at the vertices of the polygon.
	www.nvnews.net /articles/interpshading.shtml (874 words)

	Comp 136 --- Fall '96 --- Lecture 24 (Site not responding. Last check: 2007-10-07)
		Shading can be a costly process involving the computation of and normalizing of vectors to light sources and the viewer.
		Another shading method applies the illumination model on a subset of surface points and interpolates the intensity of the remaining points on the surface.
		A special case of this method, called Phong Shading (not to be confused with Phong's illumination model), occurs when the surface normal is linearly interpolated accross polygonal facets.
	graphics.lcs.mit.edu /classes/6.837/F98/Lecture18/Shading.html (348 words)

	SHADING MODELS (Site not responding. Last check: 2007-10-07)
		The main drawback of the flat shading model are the discontinuities of color along the boundaries of the triangles.
		Gouraud shading deals with this problem by using linear interpolation of color to shade triangles.
		However, it's better than the flat shaded cow with the same number of triangles (the first image) and much cheaper to render than the cow modelled with small triangles (second image).
	www.cc.gatech.edu /classes/AY2003/cs4451_spring/linint.html (485 words)

	Citations: Continuous shading of curved surfaces - Gouraud (ResearchIndex) (Site not responding. Last check: 2007-10-07)
		Gouraud shading takes the normals for each vertex and calculates the color value for each of them, then it interpolates the color values of other points in the polygon linearly.
		The Gouraud shading algorithm requires that the normal is known at each vertex of the polygonal mesh.
		Shading consumes a substantial part of the rendering computation and involves many perceptual issues and is thus an appropriate area to look for signi cant power savings.
	citeseer.ist.psu.edu /context/108040/0 (2358 words)

	Phong Shading and Gouraud Shading
		During the implementation of Z-buffer hidden surface removal in Phong Shading and Gouraud Shading, the rasterizing of polygon is to be implemented to fill the polygons with the pixel value.
		Demo A to E is the Phong Shading and Gouraud Shading for n = 1, 10, 25,100 and 800.
		The advantage of Gouraud shading is that it is computationally the less expensive of the two model, only requring the evaluation of the intensity equation at the polygon vertices, and then bilinear interpolation of these values for each pixels.
	www.nbb.cornell.edu /neurobio/land/OldStudentProjects/cs490-95to96/guo/report.html (2528 words)

	Illumination and Shading Models
		Gouraud smoothes the faceted appearance of meshes, because the interpolated intensities along an edge are used to shade both polygons which share that edge.
		The biggest problem with Gouraud shading is the fact it reproduces specular shading poorly and if specular reflection is displayed, it is determined by the polygon mesh rather than the modelled surface.
		Phong shading requires intensity calculations at each point on the face, so is therefore far more expensive that Gouraud which only performs intensity calculations at the vertices.
	glasnost.itcarlow.ie /~powerk/Graphics/Notes/node10.html (1648 words)

	Gouraud Shading
		Gouraud shading is a method for linearly interpolating a colour or shade across a polygon.
		On the left is a curved surface rendered using flat shaded polygons, the other is Gouraud shaded.
		In this implementation, the highest 8 bits of a regester are used as the integer part of the shade being interpolated, and the lower 8 bits are used as the fractional part.
	freespace.virgin.net /hugo.elias/graphics/x_polygo.htm (868 words)

	Gouraud Shading (Site not responding. Last check: 2007-10-07)
		Gouraud shading interpolates colours across a polygon from the vertices.
		Triangular Gouraud shading is invariant under affine transformations.
		Gouraud shading gives bilinear interpolation within each trapezoid.
	medialab.di.unipi.it /web/IUM/Waterloo/node84.html (97 words)

	CS184 Lecture 30 summary
		Gouraud shading is a method to remove facetization effects on polygonal meshes (IndexedFaceSets in VRML) and to make them appear closer to smooth surfaces.
		Without Gouraud shading, the brightness of a polygonal facet is nearly constant, since it is the dot product of the facet normal with the light shource direction.
		In Phong shading, the normals are linearly interpolated from the vertex normals.
	www.eecs.berkeley.edu /~jfc/cs184f98/lec30/lec30.html (608 words)

	3D Pipeline --Part II: 3D Pipeline Tutorial (Site not responding. Last check: 2007-10-07)
		Flat Shading: The simplest of the three models, here the renderer takes the color values from a triangle's three vertices (assuming triangles as primitive), and averages those values (or in the case of Direct3D, picks an arbitrary one of the three).
		But unlike a surface normal that is perpendicular to a triangle's surface, a shading normal (also called a vertex normal) actually is an average of the surface normals of its surrounding triangles.
		And similar to the Gouraud shading method of interpolating, Phong shading first interpolates normals along triangle edges, and then interpolates normals across all pixels in a scan line based on the interpolated edge values.
	www.extremetech.com /article2/0,3973,1164566,00.asp (918 words)

	FS 3D Guide: Filtering and Lighting
		Phong shading is so computationally intensive that it is not feasible to use in real-time without having some serious hardware action going on.
		What differentiates Phong shading from Gouraud shading is that instead of doing the work to find out the intensity for light and shading on the vertices of the polygon, you do it for each pixel.
		In the case of Gouraud shading, the intensities for the pixels on the surface of the polygon are determined by the normals of the vertices only, so there is a smooth shading across the polygon's face.
	www.firingsquad.com /guides/videolightfilter/page7.asp (366 words)

	Computer Graphics : Illumination and Shading : 31 / 32 : Phong Shading
		In Phong shading (1975 - Phong Biu-Tuong)(not to be confused with Phong's illumination model), the surface normal is linearly interpolated across polygonal facets, and the Illumination model is applied at every point.
		The illumination model is applied at every point on the surface being rendered, where the normal at each point is the result of linearly interpolating the vertex normals defined at each vertex of the triangle.
		Phong shading will usually result in a very smooth appearance, however, evidence of the polygonal model can usually be seen along silhouettes.
	escience.anu.edu.au /lecture/cg/Illumination/phongShading.en.html (201 words)

	AnandTech: All About Lighting
		Gouraud Shading is used in virtually all single pass rendering engines.
		Gouraud Shading calculates an intensity at each vertex of a polygon, and then LINEARLY interpolates the intensities along polygon edges and across polygon rows.
		Not only does Gouraud not shade correctly for most cases (actually all cases, but polygons viewed from the side are relatively accurate, or, at least look good), Gouraud shading produces an intensity warp, since the intensities are LINEARLY interpolated, they do NOT take into account the 3D properties of the polygon.
	www.anandtech.com /showdoc.aspx?i=383 (574 words)

	Gouraud Shading (Site not responding. Last check: 2007-10-07)
		Gouraud shading, also called intensity interpolation, provides a way to display smooth-shaded polygons by defining the RGB color components of each polygon vertex.
		To illustrate Gouraud shading, consider a polygon with four vertices.
		Strictly speaking, Gouraud shading involves not only drawing the shaded polygon, but first determining suitable RGB values for each polygon vertex.
	www.fastgraph.com /help/gouraud_shading.html (268 words)

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