Commons:Featured picture candidates/Image:Pyrenees topographic map-fr.svg

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Image:Pyrenees topographic map-fr.svg, featured[edit]

Topographic map in French of the Pyrenees mountains

  • « no scale in the map  » : well, looking at your nice work, I imagine that you know that a scale on a digital map doesn't represent lot of things : I may write that it is a 1:500.000 scale (for example), but in this "1 unit" (cm, inches, etc.), will you have a strait line or curves ? Two maps of the same size may give the same scale, but not with the same accuracy. Secondarily, do you know many paper maps giving the scale under the 1:xxx.xxx form plus the distance scale ?
  • « no indication of the map projection » : for sure, you didn't read the complete summary, where it is written : « UTM projection ; WGS84 geoid ». I do not know until now in Wikipedia (but of course, I don't know them all) a topographic map giving both the information of projection and the geoid used.
  • Please explain for the incomplete legend. Sting 04:30, 24 June 2007 (UTC)[reply]
  •  Info - I would call this a “general reference map” (like those on the atlases), rather than a “topographic map”, due to the relatively small detail and high level of cartographic generalization. I have enlarged it to a scale of about 1: 1 million, which appears to be a more than reasonable upper limit of use. Even at this scale the information density is quite small when compared to a common atlas’ map (for example, the cities shouldn’t be represented with dot symbols at this scale). Also, this is not a true digital map, comparable with Google Maps, since the level of generalization doesn’t change with scale. This might indeed be useful as a printed map. But for that purpose, a numerical scale is needed, besides the graphical one. Please note that a map is not just a beautiful drawing that we can reduce or enlarge at will. All printed maps always have a nominal scale associated with it, which is closely related to the spatial and thematic accuracy of the information depicted, and to its level of cartographic generalization. In paper maps, the length of 0,25mm (which is the typical thickness of a thin line) is normally taken as a reference for planimetric accuracy. In a map with a scale of 1:50 000, this means that the horizontal accuracy of the survey was, at least, 0.25 x 50 000 = 12 500mm = 12.5 m. In other words, it is guaranteed that the error in the position of all objects depicted in the map is less than 12,5m. When we enlarge that map by a factor of 10, keeping the line width of 0,25mm, we are implicitly assuming that the horizontal accuracy is 1,25m, which is wrong. And when the nominal scale of the map is not even stated, the map becomes useless for anything other than trivial applications. That is precisely the problem with the svg format.
OK, I understand now what you meant by « scale ». In fact it would be more about the accuracy of the drawing. For further discussion about this point, please refer to the post I leaved in your discussion page.
  • I really mean "scale", not accuracy. The map should contain a indication on the the maximum scale to be used in printed versions (together with the corresponding paper dimensions) - Alvesgaspar 11:03, 26 June 2007 (UTC)[reply]
Of course, zooming in the map with a ratio over 1:1 will not give more information, it will just make it more legible, as for a raster image. It's also true that it's not a « pure » topographic map in which everything is in scale. Here, the river lines doesn't represent their true width and, like you wrote, the cities should be represented with their real area, but for all that, the scale should be much bigger and it would be impossible to represent the whole area. Sting 21:06, 25 June 2007 (UTC)[reply]
  • In a "pure topographic map" exageration is also used in the thickness of lines in order to make certain objects visible or more conspicuous, that is not the point. To be truly "topographic" much more information should be depicted and the "working scale" should be much larger than this map permits. Anyway, even at 1:3,000,000 (which is a reasonable printing scale for this map), area symbols (instead of point symbols) should be used to represent cities (at least, the bigger ones). - Alvesgaspar 11:03, 26 June 2007 (UTC)[reply]
  • In your map, the legend is not complete because it does not contain all the types of symbols used in the representation. The indication of the map projection should be present in the map itself, not only in the Commons file. Remember that many pictures are used in non-wiki projects. Finally, the WGS84 is not a “geoid” but a geodetic reference system (containing, in particular, the definition of the “ellipsoid” used ). - Alvesgaspar 10:09, 24 June 2007 (UTC)[reply]
For the legend, I thought the signification of the three lines were almost trivial, but all right, I added them. About the projection information directly on the map, I think it's a point of view. I created this map (and the others) first for WP and the complementary information is in the description page. If a third party wants to use it in a correct way, they should take what they need also from the description page and not only the image, as they should with the license and the author name. I think also adding too much information not indispensable for a direct understanding of the map would unnecessarily complicate the key, so I left them in the description page (sometimes, there's not much space left on the map). About « geoid », sorry, my mistake : I made a shortcut between the reference frame and the geoid it tends to represent. Sting 21:06, 25 June 2007 (UTC)[reply]
Thanks. Sting 21:06, 25 June 2007 (UTC)[reply]
  •  Info New version uploaded with the borders and projection info in the key and major cities areas. The description page was completed with indication of the data accuracy. Sting 00:30, 2 July 2007 (UTC)[reply]
result: 8 support, 1 oppose, 0 neutral => featured. Simonizer 07:03, 3 July 2007 (UTC)[reply]
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