Talk:Orthographic projection

Third angle projection

User:W3bu53r Why third angle projection is considered more intuitive compared to first angle? Personally, I think 3rd angle projection is fine, and it makes more sense than first angle. I don't mean to start flame war between US vs. the rest of the world here. Someone enlighten me, please.

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Ben Axelrod: I think the picture is very helpful in illustrating this concept. Did Wapcaplet delete the link accidentaly?

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I bumped into an extremely good resource on the subject of orthographic projection, specifically axonometric projection. Someone ambitious might use this resource as a starting point for a great series of articles on 3D projection. This someone might be me! Of course, help would be more than welcome. -- Wapcaplet

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See Graphical projection Pat 16:29, 22 Feb 2004 (UTC)

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Coloration is great, Wapcaplet. I hope the other figures might also be similarly colored. But note there is now a size difference between the two pages and the figures no longer align vertically. If in coloring the the top page the size might be maintained (the larger the better for clarity) and also the size of the lower returned to its orginal, then we have the best of both worlds - color plus figures aligned vertally. Pat 15:18, 24 Feb 2004 (UTC)

Any way to punch up, Perspective Distortion, Source? Pat 18:35, 24 Feb 2004 (UTC)

Yeah, I noticed the size problem after uploading. It has been fixed. The images were not really resized, though I did remove some whitespace from between the different illustrations to make the whole image smaller; reduced screen real estate and file size without compromising on detail. Converting to PNG format helped a bit too - if you have other images like this to upload in the future (diagram-like with few colors), PNG is probably the best image format to use; JPEG is likely to introduce visual artifacts and muddy-up the diagram, since it's designed more for photographic continuous-color images. Just a suggestion :-) I'll see if I can't do something with the perspective distortion illustrations too... -- Wapcaplet 21:16, 24 Feb 2004 (UTC)

P.S. - in fact, if you could possibly use PNG versions of the images on Perspective Distortion, Source, that would be better (and easier to add color to) - as you can see, some of them suffer from blurriness and other problems caused by the JPEG compression. Assuming you have higher-quality originals of these images, I bet you will be much happier with the results that converting to PNG gives you. -- Wapcaplet 21:20, 24 Feb 2004 (UTC)

Suspect blurriness is from H-P scan. Think I must have done it as a 'document'. Will try again as a "text and graphics as image" h-p scan. Pat Kelso 17:17, Feb 25, 2004 (UTC)

If I recall HP's scanning software correctly, I think "line drawing" or "black and white drawing" will probably give the best results. But definitely save them as PNG instead of JPEG, since I'm certain that is where some of the blurriness comes from :-) -- Wapcaplet 19:12, 25 Feb 2004 (UTC)

The sequence in which the two main topics are presented would seem reversed. Without objection will reverse the order in which they appear. Will leave this post up a few days for objections...... Pat Kelso 00:17, Mar 27, 2004 (UTC)

DAB

I added a disambiguation message to the top of the page and linked to Orthographic projection (geometry). This article is wonderfully written, but I think it needs to be better disambiguated. The material covered seems to be about drafting and engineering use of the term orthographic projection, but that is just one of the many meanings. From searching online, I found at least three different, but related, meanings:

1. Map projections
2. Drawings (which is posted here)
3. Transformation Matrices (which I put at Orthographic projection (geometry))

Let me know what you all think. -- jaredwf 12:14, 12 May 2004 (UTC)

Mmm ... User:Pat Kelso has put a lot into pages all around descriptive geometry. This is good stuff; but needs perhaps top have some broader intro bits at the start. Charles Matthews 16:05, 12 May 2004 (UTC)

I added a stub for and disambiguated Orthographic projection (cartography). -- jaredwf 12:25, 13 May 2004 (UTC)

Page format problems?

When I view this page the format seems all wrong (blank space) and when I try to view one of the graphics (which show up as links - .png files) I am directed to an upload page? I have tried both Firefox and Explorer browsers with same results. Is this my ignorance with default setup (I'm new) or is there a page problem. The info is very helpful, I found the graphics elsewhere.

Standard Symbols

"NOTE: The images displayed are reversed. Third angle symbol has view into cone on left and side view of cone length on right; First angle symbol is side view of cone length on left and view into cone on right. You are encouraged to cross reference with other sources until this image is fixed."

A very confusing note. What it means is that the images are mirror-images of the correct standard symbols, not that the FR and US labels are swapped. They do indeed show first and third angle projections correctly. (The mirror image of a first or third angle projection is itself a first or third angle projection, respectively.)

See this BBC page for a correct example: [1]

In particular, I find "view into cone" confusing because it seems to imply that you're looking into a hollow object, something like a waste bin on its side. But the object is actually a solid, and you're looking onto its truncated end.

In any case, the images should be fixed and the note removed.

--84.9.78.13 15:56, 4 March 2007 (UTC)

Really a perspective projection

Some mention should be made that orthographic projection is really a hypothetical form perspective projection—one where the camera lies an infinite distance away, and uses an infinite amount of zoom. Here are some links: [2][3] (sorry I couldn't come up with anything better). SharkD (talk) 19:33, 17 December 2007 (UTC)

An animation is described here that shows a transition between normal and orthographic perspective. They may be talking about this. SharkD (talk) 03:26, 18 December 2007 (UTC)

I created my own animation depicting this. It might be better suited for a Parallel Projection article, but I don't find the current one (a redirect) satisfactory. It's too math-related. The image really wouldn't be suitable for that article. SharkD (talk) 19:55, 2 January 2008 (UTC)

I don't understand the quadrant stuff

The article could really use an image showing quadrants I, II, III and IV, as well as H and V. I don't understand the text by itself. SharkD (talk) 19:53, 2 January 2008 (UTC)

I figured it out and went ahead and created my own image. SharkD (talk) 21:28, 2 January 2008 (UTC)

Suggest split

I suggest splitting the multi-view stuff into its own article, and reducing its presence in this article to a stub and link, like it is for Pictorials. SharkD (talk) 06:23, 15 November 2008 (UTC)

I think that would indeed be more consistent to how the various projection articles are laid out right now. --Allefant (talk) 13:40, 15 November 2008 (UTC)

OK, I split them into two articles. SharkD (talk) 02:05, 19 November 2008 (UTC)

Affine transformation

In mathematics, in particular linear algebra, orthographic projection of a single plane is called an affine transformation. I didn't see any mention of affine transformations in the article so I linked this article to that one by adding a suitable clause to the lead. --Vaughan Pratt (talk) 14:08, 12 December 2008 (UTC) visit beanie kids .com —Preceding unsigned comment added by 92.7.29.24 (talk) 18:28, 30 March 2009 (UTC)

More diagrams?

I found this article to be hard to understand. Perhaps another informative diagram or illustration on Orthographic projection would help? What about a rendering of a 3D model in orthographic projection, or an architectural drawing of an automobile. thinsmek 19:36, 20 January 2011 (UTC) — Preceding unsigned comment added by Thin Smek (talk • contribs)

Discovery of orthographic projection

I have a reference to a claim that the principles of "orthographical projection" were discovered by Peter Nicholson in 1813 but before I add it to the article and to Nicholson's biographical article I'd like to try to research it further and to give others a chance to comment. —MegaPedant 13:34, 1 February 2011 (UTC)

Orthographic projection was developed in Classical Greek times and had been used by many maps before 1813. Strebe (talk) 18:43, 1 February 2011 (UTC)

See Snyder 1993, “Flattening the Earth” pp. 16–18. To wit, “Hipparchus used the equatorial aspect [of the orthographic] in the second century B.C. to determine the places of starrise and starset, while the Roman architect and engineer Marcus Vitruvius Pollio, ca. 14 B.C., used it to construct sundials and to compute sun positions. ¶The name analemma, then applied to a sundial showing latitude and longitude, was generally used until François d’Aiguillon of Antwerp promoted its present name in 1613. Vitruvius, however, apparently originated use of the term orthographic (from the Greek orthos, or ‘straight’, and graphē, or ‘drawing’) for the projection. ¶It appears in woodcut drawings of terrestrial globes of 1509 (anonymous), 1533 and 1551 (Johannes Schöner), and 1524 and 1551 (Apian)…” And so on. Strebe (talk) 01:56, 2 February 2011 (UTC)

You ought to add this to the article. —MegaPedant 06:35, 2 February 2011 (UTC)

I think that the type of orthographic projection to which Nicholson lays claim is that listed under the category "Multiview orthographic projections", now the subject of a separate article. In that article much of the work is attributed to Gaspard Monge though the claims are uncited, as is Monge's biographical article. Both articles are good but their value is diminished by their lack of references to substantiate them. When I edit I only add a fact if I can back it up with a reference. Monge (1746–1818) and Nicholson (1765–1844) were contemporaries so it is quite possible that, working independently, they could have developed a similar technique, a parallel of Leibniz's and Newton's work on calculus. In fact, in my source Nicholson compares his method with that of Monge and declares them to be "as differently conceived as can be, each having its peculiar advantages and peculiar claim to originality in the problems and examples, which are by no means common to both." So I think my original suggestion is worth pursuing, for a while. —MegaPedant 07:22, 2 February 2011 (UTC)

Good question, and one that should be asked at Talk:Multiview orthographic projection.

I'm not sure who wrote the above because it isn't signed. I agree with what you say but the term orthographic projection has come to mean a number of different things to different people. In addition to Multiview orthographic projection there are articles entitled Orthographic projection (geometry) and Orthographic projection (cartography) and then there's this one, which I would expect to be the one that bound the other, related subjects together and disambiguated them. Instead it seems unsure about its purpose and makes for a confusing read. None of the articles is well provided with citations. —MegaPedant 18:25, 17 February 2011 (UTC)

Yes, it’s a mess. At the least there should be a disambiguation page. Feel free to help. Strebe (talk) 20:15, 17 February 2011 (UTC)

References

Classification

I was taught in an OSU class that pictorial projections are not a subcategory of orthogonal projections, but a distinct category. Why is the stuff about pictorials here? --Robert the Devil — Preceding unsigned comment added by 164.107.190.45 (talk) 00:17, 20 July 2012 (UTC)

I just noticed this. I will fix the article. SharkD  Talk  06:33, 20 November 2015 (UTC)

Merger with Orthographic projection (geometry) and Orthographic projection (cartography)

The Orthographic projection (geometry) and Orthographic projection (cartography) articles both cover subcategories of the subject of this main Orthographic projection article; the geometry article is about the geometry behind orthographic projection, while the cartography article is about the application of orthographic projection to cartography. All of these articles are quite short and, even if the subarticles were expanded, summaries of the subarticles should be included as sections in the main article. At present, however, the subarticles are so short that merging them here in their entirety would result in a reasonably sized article, therefore that seems to be the most preferable option. Neelix (talk) 16:22, 4 June 2014 (UTC)

The cartography article isn’t “quite short” and will only expand. It’s also very different in emphasis. Other projections have cartographic-specific articles, and ought to: even the nomenclature of the mathematics differs entirely. It’s a different domain. Strebe (talk) 07:36, 5 June 2014 (UTC)

Does that mean that you agree with the geometry article being merged here? Neelix (talk) 16:45, 5 June 2014 (UTC)

No. The description in the Orthographic projection (geometry) article is in terms of linear algebra, which has nothing to do with the cartographic literature. Strebe (talk) 01:05, 6 June 2014 (UTC)

I am not asking whether you think that Orthographic projection (geometry) should be merged into Orthographic projection (cartography), but rather whether you agree that Orthographic projection (geometry) should be merged into Orthographic projection. That issue is irrelevant to cartography. Neelix (talk) 15:36, 6 June 2014 (UTC)

Sorry; I lost track of where “here” was when I responded. I’m less averse to merging Orthographic projection (geometry) into Orthographic projection. I’m not sure why they were ever separate, although it may be that, like cartography, geometry has its own specific emphasis, nomenclature, and significance for the projection. Strebe (talk) 04:54, 7 June 2014 (UTC)

History section

I think the History section should be removed from the article because it deals only with cartography, and is duplicated in Orthographic projection in cartography. Why write about it twice when it isn't even the main focus of this article? SharkD  Talk  03:57, 26 April 2017 (UTC)

Apologies for letting this slip this long, SharkD. I agree it's troublesome to duplicate the information from the cartography-specific article. People may well want to know the origins and etymology, though, so perhaps we should direct them to the cartography page in the History section? Other ideas? Strebe (talk) 17:45, 8 May 2017 (UTC)

I will just move 'History' to a sub-section of 'Cartography' I guess. SharkD  Talk  02:58, 9 May 2017 (UTC)

Parenthetical

Regarding this edit: The term axonometry, and hence axonometric projection, was coined in Germany and still retains its original meaning in European text books. It is worth noting in the article. See the discussion here. The fact that this is English language Wikipedia doesn't mean we can't talk about non-English language topics. ➧datumizer  ☎  21:09, 6 June 2019 (UTC)

@Datumizer: The text you inserted is, “(in English language regions)”. It’s nothing about German or European locales and nothing about why you’re inserting this parenthetical. The literal meaning of your parenthetical is, The term for this in English is “axonometric projection”, which, in an English encyclopædia is redundant and looks utterly out of place. It would be the same as saying, A baked confection based primarily on flour and eggs and sugar is called a “cake” (in English language regions). If you are trying to say something else, then please find a way to say it that is intelligible to readers who really have no idea what you’re getting at. Strebe (talk) 21:51, 6 June 2019 (UTC)

Inverse matrix of an orthographic projection

The article mentions that:

"The inversion of the projection matrix P−1, which can be used as the unprojection matrix is defined: ...".

According to https://math.stackexchange.com/a/311353 , a projection matrix should have no inverse (as you effectively lose one dimension's information in the process). Therefore, either I did not understand this line correctly or this line is wrong. Either way, I think that it should be clarified or removed.

Donaldrunk (talk) 09:16, 29 March 2020 (UTC)

"The inverses of two projection matrices can be used to regenerate the object location matrix." ? --Turbojet (talk) 11:56, 20 March 2021 (UTC)

Say more to introduce the matrix at the beginning of the geometry section.

Please provide more background as you introduce the matrix at the start of the geometry section. What are the row and column coordinates of that first matrix? Thanks! --Lbeaumont (talk) 11:40, 23 August 2021 (UTC)