Talk:Contour line

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[edit] contour crossings

Can contour lines ever cross each other? Explain your answer —The preceding unsigned comment was added by 68.125.81.140 (talk) 00:45, 25 January 2006 (UTC)

Yes, at a saddle point. Charles Matthews 08:26, 25 January 2006 (UTC)
Also at a shear cliff the lines will lie on top of each other. You can have the contours cross completely for multivalued functions. The geographic equivilent would be an large overhanging piece of rock. The contour corrisponding to the altitude that is the top surface of the rock (or a fraction below it in fact) would follow the edge of the overhang. The contour for the altitude just above the ground ok? beneath the overhang would go right up to the cliff wall, intersecting the higher one. This would create a zone (for example) that belonged to both "Above 100m" and "Below 50m" simultaneously, which is of course possible if the ground is at 45m and with an overhang at 105m. —The preceding unsigned comment was added by 195.157.136.194 (talk) 13:52, 17 March 2006 (UTC)

[edit] question

How did early map makers estimate contour lines? or put another way, how did they know their level according to sea level? i understand the use of altimeters, but not the practise. —The preceding unsigned comment was added by 86.5.55.199 (talk) 18:34, 13 February 2006 (UTC)

answer: see surveying article.--Natcase 04:36, 21 December 2006 (UTC)

[edit] merger

ok to merge isoline into contour line...no real diff Anlace 14:20, 1 June 2006 (UTC)

isoline/contour line, very much the same thing, merge is good idea User:LordHarris 22 June 2006

merger completed ...no content was lost Anlace 08:20, 2 July 2006 (UTC)

[edit] Contour map should redirect here, not to topo map

just look how many different applications are served here. that redirect seems appropriate to arrive at this article.Covalent 23:39, 17 September 2006 (UTC)

done. --Natcase 04:36, 21 December 2006 (UTC)

[edit] merge

I suggest merging all (or nearly all) of the "iso-" article stubs into this single article, organized by subject area. I've reorgnized the list of isopleth types as a starter. There are generally references to thematic articles (for example light pollution for isophote), which put the specific example into a good context. I'm putting merge markers on a bunch of them tonight.--Natcase 04:36, 21 December 2006 (UTC)

oppose myriad mergers. this will lead to a very large unwieldy article when the topics are fleshed out. Anlace 05:05, 21 December 2006 (UTC)
I revise my suggestion. Some current links go to irrelevant articles (isochrone for example has nothing to do with drive time) and should be delinked. Others are clearly important in their subject areas (isogloss for example), so a more judicious mix of moving stubs here, and referencing full articles, and more disambiguating terms with multiple uses... this could be a bit of a project. My goal, Anlace, is to get rid of the stubs that are essentially Wiktionary entries, and which if fleshed out would largely repeat what should be said generally under "contour lines." See isobar for examples of content that ought to be here.--Natcase 05:10, 21 December 2006 (UTC)
This revised intent sounds fine and i support revised merger. I suppose we can always do a split if someone can create a large article out of one of the merged stubs. regards. Anlace 05:45, 21 December 2006 (UTC)

As far as I tell from a quick Internet search, in English the word "isohypse" is mainly used with its specific meaning in meteorology. In geology, it is sometimes used as an alternative to "contour line" for describing the boundary between rock formations. I haven't found it being used to refer to land surface contours, except in text that seems to be based on Wikipedia, or in text in German (it seems that "isohypse" and "Höhenlinie" are both used to mean contour line). Therefore I suggest that isohypse is kept just for its meteorological meaning (or as a redirect to a meteorological article); the lurid example image could be moved to cartographic relief depiction. JonH 12:37, 21 December 2006 (UTC)

The list of "iso-"s feels a little like the "encyclopedic" lists of names phobias. I like how -phob- handles this, seeing also phobia and specific phobias (though inthis case I don't think we need three articles. I think non-list sections by area of study would help give some sense of context and perspective to the whole. Though I won't place bets on someone with a bent for lists coming in later and resurrecting the lists themselves (maybe that's why we need a separate article for the list). In an encyclopedic sense, I thinks the current list is missing things. Not sure what, but we could probably invent some cool iso's ourselves. Isowiki, for example (lines showing equal density of wikipedia article writers as a percentage of the general population) —The preceding unsigned comment was added by Natcase (talk • contribs) 05:47, 22 December 2006 (UTC).

merging has begun. cleanup and expansion are needed...--Natcase 04:40, 10 January 2007 (UTC) merge is now complete as proposed; removing merge proposal header.--Natcase 16:14, 13 January 2007 (UTC)

[edit] Lost contours

for a long time this article listed "air quality contour" and "noise contour" as recognized terms. these terms are in fact extremely common and important in the fields of urban planning, highway design and environmental health. where did these go? they must be restored. regards. Anlace 16:42, 10 January 2007 (UTC)

The links went away becaue the list was for specific names of contour types, not types of maps where contours are used. Those two listings were in the form of "noise: countour line" instead of "noise: isodecibel" or whatever the term (if any). You are right, they should be in here somewhere. The point was made above that "isohypse" (for example) is infrequently used, and I suspect a lot of the other "iso's" are spurious or at least infrequently used, and so perhaps the "list of isos" should be modified to be a more general list of subject areas, whether the used specialized terminology or the more generic "contour line."
The question raises another one, though. We should include at least some discussion of 3-dimensional visualizations using contours. I know nothing about them though; anyone?--Natcase 04:14, 12 January 2007 (UTC)
so where should the air quality and noise contours be discussed. under meteorology? or under an other environmental factors heading? i could add something to the 3-D issue but it is a vacuous discussion without a good graphic. Anlace 04:48, 12 January 2007 (UTC)
I've altered the format to make it more article-like and less list-like; there is now a place for enironmental science. Feel free to rewrite/replace the filler I added.--Natcase 13:58, 12 January 2007 (UTC)


[edit] Specifics on non-map applications?

So far, all the specificity applies to map applications. Some specific discussion on non-map applications would be welcome. Any suggestions on existing wiki sources to pull from?--Natcase 23:41, 23 January 2007 (UTC)

i agree. i will work on this as i have time. its on my "to do" list. there are some speciifcs that can be pulled in from noise barrier for example. Anlace 00:33, 24 January 2007 (UTC)
Isobars (for constant pressure), isotherms, and other iso-lines are used in graphs in thermodynamics and other science and engineering applications. They are useful in representing more than two dimensions on a two dimensional graph. I think some discussion on this would be useful somwhere in Wikipedia. H Padleckas 00:52, 11 August 2007 (UTC)

[edit] Meteorology

No mention of isohypses in section on meteorology. No mention of constant pressure charts. No met categories either. JMcC 13:20, 3 April 2007 (UTC)

For my comments on the use of the word isohypse, see the "merge" section further up this page. The existing surface weather analysis article is already quite long, but it does not really discuss air pressure. I think there needs to be a new article that describes how air pressure affects the wind (and it could explain the use of charts that show isobars and isohypses), but I do not know enough about meteorology to write such an article. JonH 13:08, 4 April 2007 (UTC)

[edit] Line colour

I have removed the claim that "the Ordnance Survey changes contour lines from brown to grey to indicate bare rock and scree." I use OS maps a lot and have never seen this distinction. At both 1:25000 and 1:50000 scales, contour lines are always brown. Rock and scree are shown using other symbols. However, certain Swiss topo maps do use grey contour lines on rocky ground. It is much clearer IMHO. 143.252.80.100 16:53, 9 May 2007 (UTC)

[edit] image demoing concept

Contour lines
Contour lines

I'd like to add this image to the article. Anyone agree/disagree?-Ravedave 04:10, 15 June 2007 (UTC)

  • It looks good to me. JonH 08:52, 15 June 2007 (UTC)
Looks like a nice image. Add it with the proper context somewhere in this article. H Padleckas 01:02, 11 August 2007 (UTC)

[edit] uh and

all comics and manga, all sketch art, flash art, Bizantine art...basically everything, or wait...is this not the appropriate term in american English? --AnY FOUR! 04:38, 27 July 2007 (UTC)

Yes, the proper term in American English for what you describe is "outline." There may be some further discussion in articles on art, not sure. --Natcase 20:39, 5 August 2007 (UTC)

[edit] WikiProject class rating

This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 09:46, 10 November 2007 (UTC)


[edit] Contour line question

How are caves and overhangs "handled"/shown with contour lines? Jackiespeel (talk) 23:00, 7 December 2007 (UTC)