Wikipedia talk:WikiProject Geographical coordinates/Archive 2

message: Seems like a really brilliant idea if you ask me, just needs some thought and consideration when implementing. I'm sure there are ways around the http: thing, for those who have Worldwind installed locally. For those who have not, do you know if there are any public servers where this can be accessed? -- Egil 08:16, 1 Mar 2005 (UTC)
replies: text: Worldwind itself connects to public servers to get its data, i.e. Landstat7, USGS, MODIS, SVS, WMS, Blue Marble. Its unique feature is combining all of them in a pretty (3D) format. You can zoom from seeing an entire globe, to seeing individual houses (at least in the US, everywhere else the resolution's a bit worse). I don't think there are any public servers running the software itself. It would require a server with 3D graphics abilities doing the equivalent of generating screenshots with the program. The code is open source, so perhaps it's doable, but I think it would be a major undertaking. (And not one for the Wikimedia developers really.) Should we ask a dev/committee member about enabling worldwind:// links? --cfp 17:33, 1 Mar 2005 (UTC)
replies: text: No need. I have now enabled worldwind: on the demo Wiki, so that the above thing should work. I've placed it at the end of the page, so you can try it out, now. I will include the support for worldwind: in the patch that I will provide for the Wiki software. -- Egil 18:29, 1 Mar 2005 (UTC)
replies: text: Yup works fine. Thanks, my two internet addictions are now united! To give an indication of whether scale's working, the Heathrow link leads to Heathrow's main runway being about one screen across. The top Oslo link goes south east as far as Arjangs Commun and north west as far as Buskerud Fylke. The bottom Oslo link leads to Sandvika being about 25% in from the right, and Ekeberg being about  the same amount in from the left. --cfp 18:42, 1 Mar 2005 (UTC)

text: check out  on how to add new URL types, like . NevilleDNZ 03:12, 7 Jun 2005 (UTC)
thread_title:  Brilliant... 

message: I am working on incorporating a World Wind layer that provides clickable reverse links into Wikipedia. It seems to work real nice so far, but I need to spend more time on the automation process that extracts the coordinates from Wikipedia. -- Egil 10:37, 4 Mar 2005 (UTC)
replies: text: Good idea. Best of luck. --cfp 20:15, 4 Mar 2005 (UTC)
replies: text: There is a demo Wikipedia layer for NASA World Wind available via http://wiki.worldwindcentral.com/Wikipedia if anyone are interested. Any feedback would be appreciated! -- Egil 09:46, 5 Mar 2005 (UTC)
thread_title:  From World Wind to Wikipedia 

message: I'm referring on user Docu's first comment. Because all small scale maps of Switzerland are in CH1903 datum, we'd like to use them as input for the geo tag, see german proposal. For OSGB36 I saw conversion is implemented. Is this also the case for CH1903? We would be very glad not having to convert the coordinates to WGS84 manually anymore. Thanks in advance --Ikiwaner 12:00, 18 August 2005 (UTC)
replies: text: I did at one point implement input in a few coordinate systems other than WGS84, but I then decided against it. For a number of reasons: one being lack of time (which is really sufficient), one other being that it would complicate systems extracting georef meta-data from the Wikipedia articles (like measuring great cicle distances), and it complicated support of a georef database. It is bad enough to support the various formats for output. Converting input data to WGS84 should be quite easy, and it needs to be done only once for each point. I do believe there are various Swiss online maps that support online conversion to WGS84. -- Egil 16:23, 22 August 2005 (UTC)
replies: text: I see that it takes quite some time to implement such functions and makes db-queries more complicated. Converting coordinates is not easy at all especially for non mathematicians. At the moment there is an error of about 150m in northing and 80m in easting in your conversion, and we don't know whether this is systematic or just a trunctation error. There are NO exact maps with WGS84 in Switzerland. How sould the average user be able to do a correct and accurate conversion? Slightly disappointed --Ikiwaner 19:04, 23 August 2005 (UTC)
replies: text: It would seems that the Swiss map services are lacking the feature of providing WGS84 coordinates. But look at http://www.tandt.be/wis/ for help. Wrt. the error in CH1903, yes I am aware of it, but I simply haven't had time to investigate. Every country seems to have had their own coordinate system, and they are different in many subtle respects. The source code is available, see meta:Gis, so I would appreciate if you could investigate. -- Egil 06:19, 24 August 2005 (UTC)
thread_title:  Swiss grid as input 

message: PHP includes a image manipulation library called GD. I'm pretty sure that PHP includes this library by default and the code is very straightforward, I'm guessing wikipedia servers already have the capability and maybe already use it for math rendering(does anyone know how math is rendered to PNG?) I'm guessing that projecting points onto a image of a map could be done in a couple hundred lines of code.
The process works like this:
#The rendering script encounters a map tag, the tag includes:
## A references to a Wikipedia image (the image of course depicts a map.)
## A set of geo-point to pixel relations that define the map space.
## A set of projected geo-points to text relations (the text can include any wikimarkup).
#The script calculates the pixel equivalents of the projected geo-points and stores a list of pixel to text relations (clipped to the map, error text should be generated if a point is not on the map.)
#The script generates an image where numbers are overlayed at the correct points on the map.
#The script generates a text key, showing the text corresponding to each numbered point.
Ideally there will also need to be some kind of caching routines so that the image only needs to be rendered the first time it is accessed after the map tag has been altered otherwise we can default to the last rendered image and save cycles. (I don't know how to do this yet.) 
My assumption is that by defining three or more points on the map surface to define the map space, I can approximate the projection well enough for most maps, and this is an easy way for an editor to define a map image. Options for more detailed information about the projection will eventually be added to the map tag.
Later a special search page will essentially generate a map tag and perhaps find an appropriate map image. --Plowboylifestyle 03:36, 11 Mar 2005 (UTC)
thread_title: Map Markup/Projecting Geographic Points onto Images