Mapping an Earthlike planet

[Akubra]

Hi there! A few days ago I discovered the Cartographer's Guild, and being a map enthusiast (just to avoid the term map freak ), I thought "Why not join?" So I did and started reading this extremely interesting forum.

Quite some years ago I created an imaginary Australia-sized continent somewhere in the Pacific Ocean (actually it resided somewhere in my head, but you get the point). This was before computers became mainstream devices. I remember buying large A1 sheets of thick paper to pencil in sections of this continent, named Taboran (the etymology of that name is lost in the mists of my youth). Things evolved and one continent became too restricting. Much later another idea arose: at some point in the future Earth became inhabitable and if our species wanted to live on we had to search for another Earth-like planet. Several huge, autonomous spaceships were built, capable of transporting thousands of people, together with myriads of animal and plant species. Generations came and went and at some point the fleet encountered an exoplanet that looked almost exactly like Earth. After the necessary scientific tests to see if the planet was habitable the first humans set foot on Rautah.

Rautah has almost the same dimensions as Earth and orbits a star comparable to the sun. There are continents and oceans, just like we know them here. My work on it is quite limited, in fact the only thing I have is a general equirectangular map showing the sizes and positions of the continents:

Rautah_overview_140523_bs_equirect.jpg

Here's an adaptation of the same map, done with NASA's G.Projector (Winkel Tripel overlaid with Earth's continents):

Rautah_overview_140523_bs_winktrip_earth.jpg

And this is a series of hemispheres (azimuthal equal-area projection, East - West - North - South):

Rautah_overview_140523_bs_azimeqar_090.jpg Rautah_overview_140523_bs_azimeqar_270.jpg Rautah_overview_140523_bs_azimeqar_000NP.jpg Rautah_overview_140523_bs_azimeqar_000SP.jpg

I am hoping to create a series of atlas/topographic-style maps (or one huge map) keeping up with the discoveries of the future space travellers exploring the planet. In time, they will build cities to live in and some sort of communication system (probably more advanced than roads, railways and airports). They might create administrative/political divisions, protected areas, etc.

Starting from what I have now I'd like to set up a topography of the landmasses, and see how the ocean currents flow. I think that is needed to determine a rough layout of the climate zones.

But first a few questions:

1. Any comments on the size, shape and position of the continents? What about the coastlines? I've managed to fit all the land in one supersized pan-Rautah continent (like Pangaea on Earth), so that the current shapes can be attributed to plate tectonics. Looking at the southern hemisphere however, I'm not sure about the southern part of Ghaon jutting out straight towards the South Pole. And the northern tip of Eneaga looks a bit too pointy too (see northern hemisphere map).

2. What would be a good way to add a (random?) plausible topography? The idea is to make a general map with land coloured according to height (like <100m - <200m - <500m - <1000m - <2000m - <5000m - >5000m).

3. Until now I used Inkscape because I like working with scalable vectors. My original map measures 10000 x 5000px (3.65 MB). Adding more information will make it too big to handle. I would like to have a general map where I could zoom in to areas with more detail. I read about Viewing Dale in this forum. Would that be a good choice to use for this project? Does it work with layers too? (So that I could use the same map to show natural features and political divisions by switching on/off the appropriate layers.)

4. Any ideas how I could calculate each continent's area?

This has already become a very long first post, so I'll leave it at that for the moment. Thanks for having read this far!

Cheers, Akubra

[Pixie]

Welcome. There are a few around working on the same kind of project that you want (have already) to embark on, at different stages of completion.

So far, your start is awesome. I really like the shapes - diverse in aspect and size. However, I agree with you, the ortographic views of the poles have show Eneage and Ghaon (specially Ghaon) awkwardly tipping towards the pole.
If you search in this, part of the forum you will find plenty of threads devoted to figuring out plausible tectonics, plausible climates, based on the planets being "created". The next step (shall we call it the standard procedure) is to give some thought to the tectonic movements that are forming those oceans and continents.

As for your main question about map size and file size: make several copies of the original land/sea file. One will be used for tectonics/topography, one for climate issues, one for political. These three topics, at least, will already yield many many layers.
One piece of advice though - it will take time to get something really nice and the majority does not get their stuff finished. The thrill is the ride, actually, so... enjoy.

[Akubra]

Hi Pixie and thank you for your reply.

Indeed, I should give more thought to plate tectonics. Being able to puzzle the landmasses into one huge supercontinent doesn't mean that it all fits like it should. I really should delve a bit deeper into the subject. Thanks for reminding me.

Oh, I started reading your post about ocean currents and climate. Fascinating stuff! I'll definitely need it when I get to that point.

Cheers, Akubra

[Akubra]

Today I worked a bit on the shapes of some of the continents:

- Flattening the northern part of Eneaga a bit made it jut out less towards the North. The resulting bump is still going straight to the North, but it is much less obvious and I like it a lot better.
- I widened Ghaon substantially to get rid of the "bony finger" pointing towards the South Pole. Then I moved it a bit closer to Ranineo, the continent to the northeast. I like the shape of the sea between the two continents and the strait opening in the gulf to the southeast of it.
- When looking at the Southern Hemisphere I didn't like the small continent of Lohoni being so long and thin, especially the central and southern parts. So I narrowed the north-south axis a little and widened the east-west axis. I think it looks somewhat better now.

This is the current situation:

Rautah_overview_140524_bs_equirect.jpg Rautah_overview_140524_bs_azimeqar_000NP.jpg Rautah_overview_140524_bs_azimeqar_000SP.jpg

Next step is trying to figure out how plate tectonics could work...

[jbgibson]

Welcome, Akubra. Map content in the very first post - that's worth rep right there. And then some interesting geography and apt questions...

If you put a map in an equal-area projection you can use a simple trick in several graphics packages to get areas. I think serif PhotoPlus, Adobe Photoshop, and the Gimp can all tell you distribution of #pixels of this color or that-- set it to two color and you have an easy calculation for percentage land. Simple geometry gets you the overall globe surface, unless yours is oblate like Earth is instead of spherical . Then color one continent, lake, nation, whatever at a time, and you can get its size in pixels, with a short leap to size in square kilometers or acres or what-have-you. Make sense?

[Akubra]

Hi jbgibson, thanks for your welcome and your answer to my question.

Yes, your explanation definitely makes sense. My base map is an equirectangular vector map made in Inkscape. Even though Inkscape lets me measure areas, the map projection is unfit for that purpose. Somehow I didn't make the leap to transform it to an equal-area projection. I have the Gimp on my computer, but I don't use it that much. I'll have a look at it to see how I can get some results.

Thanks again for the hint!

Cheers, Akubra

[groovey]

To calculate continents' areas I use this mini-tutorial: Using Photoshop to easily compute surface area - RC Groups, there it's used for other purposes, but the concept is the same. The idea is the same as jbgibson commented, but explained with more detail. Of course, it was created for Photoshop, but it can't be too hard to do the same in GIMP, as the steps are very basic I think. Of course, I didn't have in mind the projection of the map and how that distorts "reality"... because I hadn't thought of it.

[Akubra]

Thanks for the link, groovey. Seems like an interesting alternative to jbgibsons method. I'm not sure yet if it will be applicable to the map, but it's definitely good to know another way to calculate areas.

Cheers, Akubra

[Akubra]

OK, it's tectonic time. I prepared a map visualizing Rautah's 18 tectonic plates based on this Wikipedia map. The symbols and colours are more or less the same:

- Arrows with numbers: plate direction and velocity with respect to East Nohhon (mm./year)
- Red lines: continental rift boundaries / oceanic spreading ridges
- Green lines: continental/oceanic transform faults
- Blue lines: continental/oceanic convergent boundaries
- Purple triangles: subduction zones

Rautah_overview_140528_basic_simplified_tectonic.jpg

I'm currently only concentrating on the plates and their movements. In a later phase I'll fill in the resulting islands/mountains/...

All comments are welcome. Does this map represent a plausible situation? Are there any inconsistencies? Flagrant mistakes? Did I overlook something crucial?

Thanks for having a look! Cheers, Akubra

[Pixie]

Very good!

first the little negative: I can't quite get what's going on north of Daia plate and I'm not sure I buy Ghatia plate - I think it should have broken into an east moving east half and a western moving west half long ago...

now, all the positives:
- awesome job, really awesome.
- It seems to me you first drawn it all in equirectangular projection and then re-projected. Is that right? Secondly, and what blows my minds the most is how you did those lines, not hand-painted I guess.. so, how? Please share the technique.
- the choice of colors and labels are fine, don't touch them again
- I really like Samar plate
- I really like how you use relative velocity to show the movement, I might steal that (among other things)
- the map you referred is also my base reference.