Talk:Phong shading

This 'we' language needs to be removed. —Preceding unsigned comment added by 76.28.197.243 (talk) 03:12, 20 July 2010 (UTC)

This article really needs some Wikipedia:TeX markup added. -- Karada 22:23, 13 Oct 2003 (UTC)

And a little bit about it's inventor, Wu Tong Phong.
Also, it describes Phong shading without reference to simpler shading algorithms. IIRC, Phong shading was a very simple (although computationally expensive) extension of Gouraud shading, which in turn is only an enhancement of flat shading. It's been ages since I took that CG class though so I'll leave it to someone else. -- Kimiko 14:15, 2 Mar 2004 (UTC)

It would be nice if someone had a picture comparison of Phong shading versus Gouraud shading, as there is a noticible difference --Jim Tzenes 00:03, 11 November 2005 (UTC)

• The picture provided does not show accurately the difference between gouraud and phong shading; the difference has nothing to do with the amount of vertices and/or whether there is any interpolation between the vertices. The only difference is that gouraud shading appears 'flat' (like very short fur) and phong appears 'plastic'. A new picture would be nice. —Preceding unsigned comment added by 145.99.147.66 (talk) 21:17, 28 October 2007 (UTC)

Completely agree. I think it was leaked over from the Shading article, were there's the same image with a bad paragraph mixing up shading and surface smoothing. At the very least, as under the image from at Gouraud shading, it's specified to be applied to a higher polygon model. --Danukasan (talk) 19:13, 13 April 2009 (UTC)

I don't think there is the need to merge the two articles. Phong shading is based on Phong reflection model, but they aren't strictly related. I mean, Phong reflection model is an equation to calculate the intensity of light in a known point of a known surface and in a know point of view, shading is mostly related to the selection of that point of the surface. For example, flat shading calculates Phong's model just once, and applies the value to the whole triangle. So, there are shading algorithms that are based on Phong's reflection model but aren't related to Phong shading. Another example is Gouraud shading. I have an image of the same object shaded in Gouraud and Phong, I'll scan it when I can. -Guga, Italy- 82.58.198.241 18:09, 12 January 2006 (UTC)

I don't agree with the Merge suggestion, because although they both have the name Phong in their name, they are completely different things. One is a shading model, the other is an illumination model. Matt 22:31, 16 January 2006 (UTC)

Why would wikipedia want to contribute to the confusion of two different things with the same name by merging them under the same article. I disagree with the Merge suggestion. -Ieth, Finland- ieth 13:02, 3 May 2006 (UTC)

Separate pages then

Since we decided to keep them separate, and the attempt at merging was reverted, let's do a good job of it. I've made a start at integrating the two articles better, with sensible cross-referencing statements. And I've corrected the writeup on how Phong compares to Gouraud, which was totally wrong. I copied some, but not all, of the content from this article to the other. I did some work on Phong's bio, too. Please comment, or just chip in and do what you think will help. I think we should fix the Blinn-Phong article to fit this scheme, too. Dicklyon 04:44, 30 May 2006 (UTC)

Merge

New discussion for merge at Talk:Phong reflection model#Merge —Preceding unsigned comment added by Rainwarrior (talk • contribs) 03:41, 1 September 2007 (UTC)

The discussion there found no dissent this time, so the merge was done. Dicklyon (talk) 22:08, 16 December 2007 (UTC)

Ah, thanks. I forgot to mention it here too. - Rainwarrior (talk) 00:00, 17 December 2007 (UTC)

I can't really say I'm pleased with this merge. Both are different applications. One is a refraction model, while the other generates a smoother surface, regardless if the reflectance model is applied upon the resulting surface. I suggest we clean up Shading, and clearly define the ambiguity in naming, branching out from there along the two definitions. While it may seem a tad more laborious, it would render the important subject of shading a lot more accessible. Perhaps explicitly naming one Surface Smoothness Shading, and the other Refracted Surface Luminosity Shading --Danukasan (talk) 19:28, 13 April 2009 (UTC)

Doing a better job at shading is a great idea. The present article is not bad, though. Having the two main sections on Phong reflection model and Phong interpolation is helpful in clarifying the two main parts of what is usually called Phong shading. Having separate short articles made it less clear what was what. Dicklyon (talk) 19:52, 13 April 2009 (UTC)

Image removed

Thanks Dick, I forgot that I had removed most (or all) of the phong component from that surface. The existing images on the page are much better. Dhatfield (talk) 11:08, 22 July 2008 (UTC)

Terminology

What the hell is the "diffuse component of the light source"? Diffuse and specular refer to materials. Lights just emit light. —Preceding unsigned comment added by 91.84.151.241 (talk) 15:49, 29 January 2009 (UTC)

Wrong pictures

Pictures in this article are in linear color space, but they are usually viewed on sRGB monitor, so they look completely different from an actual Phong Reflection Model rendering. 83.7.234.61 (talk) 19:11, 19 December 2009 (UTC)

phong and gouraud

maybe a gouraud shading picture should be added to the "flat shaded" . "phong shaded" blue ball ? Aint the gouraud is the ancestor to phong? But maybe it is just me being drunk... —Preceding unsigned comment added by 69.172.126.233 (talk) 01:03, 31 December 2009 (UTC)

HLSL Code Sample

Given that phong shading is a basic effect used often in HLSL I shall add a small piece of HLSL code which performs the function. --ChristosIET (talk) 13:13, 26 February 2010 (UTC)

I've done that. Please correct any errors

--Sorcerer86pt (talk) 16:12, 16 August 2011 (UTC)

Splitting into "Phong shading" and "Phong reflection model"

The merge of "Phong shading" and "Phong reflection model" was a bad idea. The page now mixes Phong shading and the Phong reflection model in a way which is certain to confuse readers who are not aware of the issue. I agree that there is an incorrect ambiguous use but there are conventions how to handle such a case in Wikipedia. I'm strongly in favor of splitting the page again into "Phong shading" and "Phong reflection model" and I assume that any professional in computer graphics will agree; thus, I don't think that this split is controversial. --Martin Kraus (talk) 10:45, 1 June 2011 (UTC)

I would rather see it fixed in one article. The things usually called Phong shading do include both the reflection model and the normal interpolation, but that can be made most clear in the one article; there's no reason that should confuse reader's if we do a good job of it. Dicklyon (talk) 11:21, 1 June 2011 (UTC)

Well, if you claim that "Phong shading" usually includes the "Phong reflection model" then please provide any scientific reference or any textbook that refers to the Phong reflection model as Phong shading. I just looked at "Computer Graphics - Principles and Practice," 2nd edition in C, by Foley, van Dam, Feiner and Hughes, and "Essential Mathematics for Games and Interactive Systems," 2nd edition, by van Verth and Lars M. Bishop, and they both refer to Phong shading exclusively as an interpolation method for normals. The terms are not ambiguous in the scientific literature on computer graphics and neither in textbooks on computer graphics. For a way to handle ambiguous terms such as "Euler('s) number(s)", have a look at List of topics named after Leonhard Euler#Euler—numbers. --Martin Kraus (talk) 13:31, 1 June 2011 (UTC)

OK, I just saw some papers that actually use the term in a way that I would consider incorrect. But nowadays most authors appear to make an effort to clearly distinguish between the terms and I think this is a good reason for splitting the article. --Martin Kraus (talk) 14:59, 1 June 2011 (UTC)

One good reason for splitting would be the possibility to refer specifically to "Phong shading" as the interpolation method of normals or to the "Phong reflection model". Currently a lot of specific references are redirected to this article which covers both topics, thus, the reader has to figure out what was actually meant by the reference. --Martin Kraus (talk) 15:05, 1 June 2011 (UTC)

Yes, I agree; the Phong reflection model doesn't necessarily have anything to do with Phong shading (nor does the inverse reflection model), which is just a way to implement it in graphics software. I'm also in favour of splitting the page into "Phong shading" and "Phong reflection model" as you suggested, although I think that we need to keep at least the definition of the Phong reflection model in this article to make it clear what it is and how it works. --Kri (talk) 23:43, 2 June 2011 (UTC)

Well, we went back and forth a few times on this in 2006/2007, so review the state of the articles at that time, and try to make it better this time if you split it. Dicklyon (talk) 03:30, 3 June 2011 (UTC)

OK, I'll try. (Another argument for splitting is the fact that articles in Wikipedias in other languages apparently are split; I checked Italian, Spanish and German.) --Martin Kraus (talk) 10:55, 7 June 2011 (UTC)

I've splitted part of this page to Phong reflection model. Please leave comments on the corresponding talk page. I suggest we use the About template here to say: This page is about Phong's normal-vector interpolation technique for shading. For Phong's illumination model, see Phong reflection model. and in the main text a short section about the reflection model (with a link to the main article about the reflection model). Would this be acceptable? --Martin Kraus (talk) 13:02, 7 June 2011 (UTC)

Nice. After the split-up of the article I took the freedom to delete a couple of sections I felt didn't belong to the respective article, plus moved the sections "Other applications" to the Phong reflection model article and renamed it "Applications". I also assume that Phong shading doesn't have to use the Phong reflection model (as stated in the section "History" in the Phong reflection model article)? I therefore edited the article headers slightly. --Kri (talk) 20:15, 7 June 2011 (UTC)

Post-split clean-up

Thanks, Kri. I did some changes to put even more emphasis on the use of "Phong shading" in the sense of "Phong interpolation" (which is the dominant way it is used today according to my textbooks about computer graphics) but I also mentioned that "Phong shading" may be used to describe "Phong interpolation" combined with the "Phong interpolation method". I think the mathematical description of the Phong reflection model and its approximation should not be part of this article in order to reduce the overlap with Phong reflection model. --Martin Kraus (talk) 22:41, 7 June 2011 (UTC)

Phong vs. Gouraud

While the benefits of Phong shading versus Gouraud shading are explained in the article, it might be nice to also have an example image which shows how Gouraud shading can be a poor choice for certain situations and how Phong shading solves the problem. — Preceding unsigned comment added by Antic-Hay (talk • contribs) 13:40, 24 July 2012 (UTC)