Getting continent shape and size right on a flat map

[Becka S]

Hi,

I know that any flat map is going to be distorted by virtue of being flat. What baffles me is how do I make sure that the shape I draw on my flat map is correctly distorted for the map type (in this case a completely bog standard plate caree) when I don't have a non distorted map to go from? Are there any good guides for working this out? I have a rough idea in my head how large the continents in my world are and where they are (By roughly it's like... continent sits on the equator with northernmost point just shy of the Tropic of Cancer and the southernmost extent about 53 degrees south, largest east west extent is about 5000 miles so maybe not that rough).

I have absolutely no idea if that made sense but hopefully it did.

Becky

[selden]

One way to do it would be to draw the continents individually as separate pictures, drawing each one as if you were looking straight down at it (i.e as gnomonic projections). Then use map projection software to reproject the individual maps onto your full map.

Another option would be to use a program like "Deep Paint 3D" to draw directly on the surface of a sphere. (Except that it looks like Right Hemisphere's Web site no longer exists )

[Becka S]

One way to do it would be to draw the continents individually as separate pictures, drawing each one as if you were looking straight down at it (i.e as gnomonic projections). Then use map projection software to reproject the individual maps onto your full map.

Ooh! That's thought. I may have to try that!

Thanks! :-)

[johnvanvliet]

there are two good programs for remapping
the first one is just "eye balling it"
it is easy to use and quick , but not very accurate

1)
MMPS
http://www.users.globalnet.co.uk/~arcus/mmps/
works also on MS Windows

2)
GDAL/Proj4
http://www.gdal.org/index.html
( text based -typing in the terminal only)

there is a GUI in the form of a GIS program Qgis
http://www.qgis.org/en/site/

using GDAL ( "gdalwarp" ) is rather COMPLEX but very accurate

[Hai-Etlik]

You might try including Tissot's Indicatrix as a layer when drawing. It consists of identical circles that have been subjected to the projection so you have an idea of how much distortion there is. The attached image has Earth's coastline, a 5° graticule, and Tissot's Indicatrix as 10° spacing (30° near the poles) all in Plate Carree projection.



I've also made a start on explaining how to create custom projections for the QuantumGIS and GDAL/OGR software which johnvanvliet mentioned: http://www.cartographersguild.com/sh...32309&p=284104

[Becka S]

You might try including Tissot's Indicatrix as a layer when drawing. It consists of identical circles that have been subjected to the projection so you have an idea of how much distortion there is. The attached image has Earth's coastline, a 5° graticule, and Tissot's Indicatrix as 10° spacing (30° near the poles) all in Plate Carree projection.



I've also made a start on explaining how to create custom projections for the QuantumGIS and GDAL/OGR software which johnvanvliet mentioned: http://www.cartographersguild.com/sh...32309&p=284104

Thanks! :-D That might well be helpful. :-)