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Reply Wed 2 Sep, 2009 05:35 pm
Identify and describe each of the four major flat-map projections???
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Type: Question • Score: 8 • Views: 1,982 • Replies: 18

 
NickFun
 
  2  
Reply Wed 2 Sep, 2009 06:01 pm
@Sabrinaa456,
Truly a difficult homework assignment Sabrina. I didn't know there were four major flat-map projections.
roger
 
  1  
Reply Wed 2 Sep, 2009 06:20 pm
@NickFun,
Three of them look down right strange.
0 Replies
 
Ceili
 
  2  
Reply Wed 2 Sep, 2009 07:19 pm
There are general or thematic,
Planimetric, topographical or charts.
Examples of maps - world, political, physical, vegetation, religious, economic, road, weather, relief, star, orthophoto, aeronautical, nautical and satellite maps and atlases and/or GPS cooridinates.
0 Replies
 
Setanta
 
  1  
Reply Wed 2 Sep, 2009 07:45 pm
You left out Mercator . . .
0 Replies
 
georgeob1
 
  1  
Reply Wed 2 Sep, 2009 07:59 pm
I believe the only geometric possibilities are projections (1) on a plane or (2) on a cylinder.

Projection on a tangent plane is called a gnomic projections. The most common are tangent at a pole.

Projection on a cylinder tangent at the equator is caled a Mercator projection - the one Setanta noted.

One occasionally encounters projections on the equatorial plane, but I don't know what they are called.
talk72000
 
  1  
Reply Wed 2 Sep, 2009 09:58 pm
@Sabrinaa456,
wikipedia:

http://en.wikipedia.org/wiki/Map_projection

National Geographic:

http://www.nationalgeographic.com/features/2000/projections/ax/content_frame.html

Others:

http://www.progonos.com/furuti/MapProj/Dither/TOC/cartTOC.html

http://egsc.usgs.gov/isb/pubs/MapProjections/projections.html

http://www.members.shaw.ca/quadibloc/maps/mapint.htm

Microsoft:
http://msdn.microsoft.com/en-us/library/cc749633.aspx
0 Replies
 
8302021
 
  1  
Reply Tue 31 Aug, 2021 10:34 pm
@georgeob1,
Mercator, though a map-projection by that term's general meaning, isn't made by actual projection.

There is a map made by projection onto a cylinder: Gall Stereographic. A cylinder is tangent to a globe around the globe's equator. For a particular point on a particular meridian, a line is projected from the equator directly opposite that meridian, through that point on that meridian, and that line is extended to the cylinder. Where it intersects the cylinder, that's where that point on the globe is mapped on the cylinder. So the projection is from the point on the equator opposite the meridian on which lies the globe-point to be projected onto the cylinder.

Then the cylinder is expanded north-south so that shapes will be perfect along the 45th parallel.

Gall-Stereographic was one of 3 cylindrical projections proposed by James Gall, a Scottish minister, in 1855.

He also proposed an equal-area projection, called Gall-Orthographic, at the same comference. It was later reinvented by Arno Peters, and known as the Peters Projection, or the Gall-Peters Projection.

It too was constructed by an actual projection of a globe onto a cylinder. In this case each point on the globe is projected onto the equator-tangent cylinder by a horizontal line (the globe's axis is vertical), originating at the globe's axis, extending out horizontally, through a point on the globe, and out to the cylinder. Where it intersects the cylinder is where that globe-point is mapped on the cylinder.

That's Lambert's Cylindrical Equal-Area. Gall expended it north-south to give perfect shapes at latitude 45 (just as he did with his Stereographic projection).

Gall Stereographic is very popular as a world wall-map. It was Gall's favorite. Gall Orthographic, better known as the Peters Projection, is also quite popular with some school-districts, and many humanitarian organizations.
jespah
 
  3  
Reply Wed 1 Sep, 2021 05:04 am
@8302021,
This topic is over a decade old
izzythepush
 
  1  
Reply Wed 1 Sep, 2021 05:16 am
@jespah,
That recent arrival is posting on the threads about maps.
8302021
 
  1  
Reply Wed 1 Sep, 2021 12:08 pm
@jespah,
Right. Do you know of more recent cartography discusion here?
0 Replies
 
8302021
 
  1  
Reply Wed 1 Sep, 2021 12:10 pm
@izzythepush,
Yes. A question: How could one contact an administrator of this forum? I have a question for administration. How do I ask it?
izzythepush
 
  1  
Reply Wed 1 Sep, 2021 12:24 pm
@8302021,
There’s a contact us link at the bottom of the page, click on that and follow the instructions.
8302021
 
  1  
Reply Wed 1 Sep, 2021 01:03 pm
@izzythepush,
Thanks
izzythepush
 
  1  
Reply Wed 1 Sep, 2021 01:12 pm
@8302021,
This is a very small website, politics and religion are the things most people talk about.

I can’t think of any specific threads on cartography.

Another thing newcomers have problems with is the way the forums are organised. The tags are put on by the poster, and only the poster, it used to be that anyone could tag a topic but that was abused by some.

It means a thread you’re interested in, on a topic you are interested in may not appear where you expect it.

Let’s take your subject as an example. Say I post a story about the ordnance survey issuing new maps of the Jurassic coast. I could tag it, ordnance survey, Jurassic coast, UK geography. If you then search for cartography or map making in forums you won’t find it. You’ll only find it if you search for one of the three tags I have put on.

It’s not exactly user friendly.
0 Replies
 
8302021
 
  1  
Reply Wed 1 Sep, 2021 01:19 pm
@izzythepush,
I tried that. When I clicked on "Contact Us", there was a screen asking for my full name & my e-mail address. I entered them in the spaces provided.

I entered my question in to box provided. I clicked "Submit".

The result was that what I'd written in all the writing-spaces disappeared, and there was a notice that there was a problem with my submission, and that I should fix the "error below". Below that notice were just the empty writing-spaces, with no indication of what the error was.

I tried using my full name. Then I tried using my login-name. Either way, I got that error message that didn't specify the error.
izzythepush
 
  1  
Reply Wed 1 Sep, 2021 02:02 pm
@8302021,
Sorry I don’t work here, I’m not a mod.
0 Replies
 
Mame
 
  2  
Reply Wed 1 Sep, 2021 02:12 pm
Also, check out the related topics below the last comment.

BTW, I just submitted on the Contact Us page and it worked just fine. Maybe try again. I used my full real name, email and a bit of text.
8302021
 
  1  
Reply Wed 1 Sep, 2021 08:19 pm
@Mame,
My question was written too long. I shortened & it posted.

Thanks
0 Replies
 
 

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