First foray into Digital Mapping!

[Straf]

Have you tried out https://www.giss.nasa.gov/tools/gprojector/ to put your image onto a globe? The exaggeration on the polar regions is insane.

[Falconius]

Unfortunately when it comes to the poles they are almost impossible to map out in equirectangular, best option is to actually map it on to a globe and draw them there and then unwrap it to equirectangular. I hear that can be done in gimp, but don't know how. If you are familiar with Blender you could do it there too, but it'd be way too much to tackle if you didn't have a grasp of the basic Blender stuff. You could use Nasa G.Projector but it'd be a lot of work going back and forth.

[Gidde]

But, here's a thought: wouldn't the excess mass make the core even hotter or at least the same as earth? For example, a 4x smaller earth with earth properties I could see cooling faster given its constituent elements, but assuming a super dense core wouldn't the initial conditions heat the core to extremely high temperatures, and then it's density would make it harder to release heat? We might be over thinking it, but it's fun none the less as a thought experiment. I mean, either way I can work it out (like you guys said, volcanoes, old tectonics, meteors, etc).


In regards to the moon, I'll look in to the Roche limit, I think someone analyzed thanos' moon throw with that on YouTube. I think our moon has some effect on the tectonics (if only slightly?) but definitely on the ocean. To be honest I haven't considered the moon(s) yet, anyone have good resources as to what happens when there are more than one?

On the hotter core: I don't think so (but I am a hobbyist, not a physicist). Maybe if your core was uranium, instead of platinum, since part of what keeps Earth's core molten is radioactive decay.

On the multiple moon issue: Nope The 3-body problem is what you're looking for, and the physics/math is WAY over my head. I failed when I got to that part of geeking out on the issue.

On another note, have you ever checked out Celestia? You can model your system in virtual space!

[kacey]

You can jump between 2D and 3D right in photoshop. There's no need to go bouncing around a bunch of different programmes, you can paint on a sphere and revert back to equirectangular and back and forth to sphere as many times as you like quite easily. I think the biggest issue would be converting what's already there into equirectangular to begin with if that's the route you decide to take...


I'm curious just how realistic you are hoping to go with this? Because if you do decide to jump down the rabbit hole, so to speak, then be prepared to do a hell of a lot of work just getting the base map working accurately in another projection.


Like Gidde I am also a recovering tectonics addict so just remember this is fantasy. Don't let all the details and scientific accuracy freeze you're progress. There comes a point (unless you're a certain type of person) in projects like this where striving for a perfectly accurate world can drive you absolutely mad and cause you to give up all together.

[Azélor]

Im figuring the world is roughly spherical just for simplicity's sake. Attached is how I kinda visualize how the south pole works, I think it works?

Attachment 111236

No, it is impossible for a specific point to be land and water at the same time. Maybe with quantum physics I don't know...
It just need a minor fix. Basically you simply need to add a small band of land along the border.
Well, if it's too thin it will still look odd.

With Gprojector, the south pole looks like this. It produces a sharp angle.

south pol.png

Another example, it's easier to see that some land is missing around the south pole with the winkel triple projection.

winkel t.png

Another thing: if your map is using an equirectangular projection (which is what we usually suggest) you should use a 1:2 size ratio instead of 2:3.

Lastly, the water coverage is 62%. You need to use an equal-area projection like Mollweide or Hammer to measure area. Mercator and equilateral stretches high latitudes a lot and exaggerate their size.
Thus Greenland is not bigger than Africa, it's about the size of Algeria.

mollweide.png

[savarast]

Holy crap you guys are helpful!

@straf: I'll look into that, that looks like fun to play with regardless!

@azelor: thank you for projecting those, it definitely shows the weirdness. In regards to the ratio, I just found what the largest print my local shop could do and used those. I'm sure I could scale it to 1:2 though. Can I also ask how you found the %water? I'm sure I should be able to get that info in Photoshop but I'm pretty novice at it.

@kacey: is like it to be logically consistent/realistic, but some things can be explained away by magic. Like I know the viability of a platinum core planet 1/4th the size of earth is really not realistic, but if you tilt your head a bit and squint your eyes it almost seems plausible. But the issue with the South pole I can't work around without doing some adjustments it seems. I'd lie to catch those types of errors the most, rather than getting hung up in too many details. Lie you said it is fantasy after all.


Thanks everyone for your input!

[Jean-Abdel]

Several big moons can't be stable over time, and planets axis won't be stable if there's no big moon so there could be huge glaciations. High density core don't makes it hotter, it's only the pressure so it will probably be colder, expect no plate tectonics. However, with such a dense core and a earthlike gravity there definitely could be a breathable atmosphere and water oceans.

[Azélor]

Can I also ask how you found the %water? I'm sure I should be able to get that info in Photoshop but I'm pretty novice at it.

The first thing is to use an equal area projection. Usually you need to convert your map because most people work on the equirectangular projection for the main map. We use that projection because you can convert it to any other projection, which can't be done with most of the other projections.

Second, once you have converted the map to an equal area projection with Gprojector (I used Mollweide in the last picture above)
save the file as a PNG and try to keep a similar size. In term of accuracy, there is no point in increasing the size of the map when you extort it.
You need PNG not JPEG because you want to keep sharp contrast. JPEG will add antialising which make area measurement in photoshop less accurate.

Once you have the PNG, open it in Photoshop.

Now you need top find 2 things:
1- the number of pixels on the map, only including the white and black areas, not the grey area around.
2- the number of black or white pixels.

You select the area with the magic wand.
To find the number of pixels, you need to open a specific window.
There is probably an option in the top menu named ''windows''. My ps is in french so things might be named differently.
Then in the scrolling menu, click on histogram. It opens a window.
Here's what it looks like :

histogramme.png

In the new window, you have to click on the top right button with a triangle and 4 horizontal lines to select the '' large display'' or something like this. By default, the window does not show all the information.
Once you select this, it will tell you the number of pixels selected with the magic wand. Depending on the size of the selection, you might need to use the refresh button at the top right after selecting the pixels. Otherwise, for some reason, the number can be very inaccurate.

[Azélor]

About the platinum core, Earth's core contain more or less 0,0000004% of platinum, only slightly more common than gold.
assuming this page is accurate: https://en.wikipedia.org/wiki/Abunda...arth%27s_crust

[Charerg]

First off, welcome to the Guild savarast! The map looks like a good start and is definitely heading in the right direction.

Regarding the poles, I'd recommend converting your map into an equirectangular projection (2:1 width/length ratio). Then you can upload it to Map to Globe, for example, to get a 3d view of the planet.

Right now, here's how your South Pole looks like:

SPole.PNG

Here's some feedback to your questions:

1) is there too much "jaggedness"?

At a first glance, I'd say the "jaggedness" is fine. However, this really depends. A mountainous, polar coastline could be very fractal, having been carved into deep valleys by vast glaciers. Similarly, lowland deltas can be mosaics of islands and inlets (think the Mississippi or Amazon deltas). That said, some coastlines are basically featureless (think South African coastline, for one). I'd say you should aim to have "some" fractalized coastlines in locations where that is appropriate, but not everywhere. Basically, vary the "jaggedness" so some coastlines are smooth while others are fractalized.

2) are there too many islands/are their placements logical?

As long as most islands are located close to landmasses, you should be fine. The numbers look to be fine, though there isn't a right or wrong answer to the question of "how many islands should I have".

3) assuming around 70-75% water, is there too much land??

If you aim specifically to have that amount of water, you could calculate the area of your landmass, but at first glance I'd say your land/water ratio is fine.

4) How far inland from a tectonic plate can I logically place mountains (I was assuming at most 1inch)?

Answer is, depends. Real world tectonics are fairly complicated. As an example, compare the coastlines of North America and South America: tectonically speaking, both plates have relatively similar boundaries, but the Cordilleran mountains are very different between the two continents. South America has very high, narrow mountains sticking close to the coastline, whereas North America has much lower mountains that cover a vast area, forming wide plateaus. Also, some areas like Asia consist of numerous smaller plates that have accumulated into a single landmass, but even the older fold belts can be reactivated by more recent events. Consider the uplift of the Altai mountains or the Tien Shan: both areas are located far inland, but they are still affected by the collision of the Indian plate with the Eurasian plate.

Hope you found the answers helpful and looking forward to where you take this!

EDIT:
Though I see that Azelor already covered the questions of the land/water ratio and projection (I suppose I should start reading a bit more than just the first page before commenting ).