How do I start with a world map and work down while maintaining scale?

[giraffev]

I am brand new to this, and would like to ask what will probably be a very stupid question. A lot of the maps I see posted here are of particular regions or continents. This is understandable and practical. However, being the anal retentive person I am, I am always left wondering... 'but what's just north of that?'

I would like to create a full world map, and then "zoom in" to do maps of each individual continent (or even regions of each continent). Is there any way to do this using photoshop, while maintaining an accurate scale, without having to redraw each individual continent or region?

[selden]

If you start with an over-all world map, you can crop out a region, then expand that image and fill in the details. Rince and repeat (FWIW, I usually use ImageMagick or MMPS when I want to be careful to extract specific regions and change their sizes and orientations in a reproducible way.)

Of course, world maps have to be projectable onto a sphere, as do the regions cut from them, which requires appropriate distortion of flat drawings. But that's an entirely different topic.

[Pixie]

It's not a stupid question. Quite the opposite, it's a very promising question.

I propose you have a look at the wikipedia page on map projections.
By starting with this, you'll understand that you need to start your world map in an image twice as wide as it is tall. And you'll also understand that that image is distorted and that there is no linear scale to fit that entire map... and that that isn't a problem.

Then you go and find about g.projector.
This is a handy little program, from NASA, which allows to switch projections and make local maps in any size, projection or shape you like.

Often, changing projection or scale messes up the definition on the images, or distorts them. Being the "kind of person" you say you are, you will end up redrawing it all many times.

[StillnessTolls]

It's not a stupid question. Quite the opposite, it's a very promising question.

I propose you have a look at the wikipedia page on map projections.
By starting with this, you'll understand that you need to start your world map in an image twice as wide as it is tall. And you'll also understand that that image is distorted and that there is no linear scale to fit that entire map... and that that isn't a problem.

Then you go and find about g.projector.
This is a handy little program, from NASA, which allows to switch projections and make local maps in any size, projection or shape you like.

Thank you Pixie! This is a good place for me to start, all the mapping i've done so far has been hand drawn in my sketchbook and then uploaded as scans into my drawing software where I just redraw my map digitally. I'd like to work on making a bit more technical maps than that. Hopefully reading through this will also give me some insight on where to start. I have an issue with starting maps by drawing in rivers first, which I've found out just by being in the forums for an hour or so is a bad idea. ^ - ^'

Thank you so much!
~Stillness

[Azélor]

If you stretch a raster image (photoshop) it will become blurry.
One solution would be to use vectors. You could try Inkscape (free) or use Illustrator if you already own it.

[giraffev]

Thanks all for your replies.

Selden and Azelor - am I correct in understanding that you're suggesting I use vector mapping for the coastlines, so that I can reproduce them at any size without noise/distortion? Do people make entire maps using this kind of software, or is it just a matter of keeping an outline of the coast so that I can use it in photoshop at any scale?

Pixie - Being the kind of person I am, I have been reading compulsively for the past 3 days and have read a fair bit about map projections. To think this all started with me wanting to play D&D with my friends... g.projector sounds awesome. I will definitely check it out!

[Azélor]

Thanks all for your replies.

Selden and Azelor - am I correct in understanding that you're suggesting I use vector mapping for the coastlines, so that I can reproduce them at any size without noise/distortion? Do people make entire maps using this kind of software, or is it just a matter of keeping an outline of the coast so that I can use it in photoshop at any scale?

Pixie - Being the kind of person I am, I have been reading compulsively for the past 3 days and have read a fair bit about map projections. To think this all started with me wanting to play D&D with my friends... g.projector sounds awesome. I will definitely check it out!

More or less. it could be useful but there are limitations.
1- On the world map, the outline will look fine but might appear low detailed on a regional map. So you need a lot of details right from the start even if they can't be seen (or hardly) on the world map. Otherwise you will need to edit the coastline later.
Very few people make maps using vector based software. While scaling is important, raster soft are generally easier to use. I do (and other too I think) use vector to make some elements of my map but I've never made a map only using vectors.
2- Line thickness could be a problem. Logically, the world map lines are thicker that local ones. The software does not change the scale of the lines automatically to make them good if you zoom in. Of course you can select the lines and change the thickness manually.

[selden]

What he said

Also, one of the problems when using high-precision raster graphics for mapping is that you soon discover that you need far more main memory in your computer than you ever thought possible.

[johnvanvliet]

also think of the image dataset size . This can end up HUGE

i have a few full ( real world) maps ( 3d textures ) that are OVER 12 GiB and two that are over 24 GiB
yes one image is 25 gig in size ( the Venus maps i have are HUGE )


however starting with a small 8192 x 4096 pixel map and zooming in on areas for city area maps will keep the dataset size down

[waldronate]

Drawing in rivers first isn't a bad idea, as long as you have a solid handle on how rivers work. Draw your rivers, then draw your mountains, then draw your coastline. Or coastline, mountains, rivers. Or mountains, rivers, coastlines. Or coastline, rivers, mountains. Any of those will work if you understand the interplay of those elements in physical geography (physical geography is an excellent search term for learning stuff, btw). Best of all, if you don't understand how those elements work together, then the order still doesn't matter, but it does a look a little odd if your rivers go up over the mountains and past the coastline into the ocean depths.

If you want a piece of software to calculate rivers for you, then you'll need mountains and coastlines. For example, my entry in this month's challenge ( https://www.cartographersguild.com/s...ad.php?t=40256 ) features many lines that look like rivers. I don't know how many: I didn't draw any of them. I taught my robotic slave to do it for me as described in https://www.cartographersguild.com/s...ad.php?t=29412 (see the CSU Johnsondale entry for how if you're of the lazy sort).

A critical part of mapmaking is abstraction: determining how much and what kind of details to put on a map. Starting with a rough whole-world map is actually a nice way to start because you can very roughly indicate placement of things and what types of biomes you'd encounter where. Then you add the story-relevant parts and you have a nice visually-oriented master index. Understand that the whole-world map is unlikely to have the precise level of detail that you'd need for any specific use, but it's excellent fodder for something like g.projector to get you a rough version of more relevant sections that you can then draw in details for.

As Pixie points out, you'll be drawing the various maps again and again. The higher-level maps are very useful in that they provide a way to ensure consistency across more detailed versions, but the precise level of detail that you need will vary from map to map. This is true even if you're starting with vector outlines: the detail that you can put into a whole-world vector set isn't appropriate for more-zoomed maps. If you try to put the same level of detail into a whole-world map that you put into a local map, you'll find that a lot of that detail just resolves to little blobs (mostly just slowing your display down).