Hello

[MollyJ]

Hello. I'm Molly. I'm one of the moderators for Xplanet. I'm always looking for bits of open source software to work with creating planet surface textures and cartographic map projection transforms.

[Redrobes]

Welcome Molly,

We do have a few people here who do earth rendering but were mostly fantasy planet creators. For earth we generally download DEM data such as the Nasa SRTM and render those height maps and for fantasy we have several applications for generating random DEM data to use as a basis for a planet creation. A lot of the discussions are about how best to use these apps to do erosion passes to make the DEM data look more realistic. Wilbur comes to mind for a free app to do that. I think there are numerous apps and libraries for doing the projection and I was under the impression that GDAL was pretty comprehensive although I have not used it much myself.

XPlanet looks interesting and whilst some of us, myself and several of the mods and admins esp, use linux or a BSD based OS, I have not used XPlanet or FXPlanet to make images. If XPlanet would take in a fantasy Mercator style image and project it then I think it would be very interesting to see a post on how you do that and what images you can get from from it. I like the idea of creating the one image and being able to specify the angle on the planet to look at it. It sounds like you can do that with command line for dynamic web pages.

[Tiana]

Yeah, I use World Creator (not free) for generating random terrain data to work with as a height map and make planet surface textures. However, Gaea has a free version as I understand, it might be something you'd enjoy.

[MollyJ]

Welcome Molly,


If XPlanet would take in a fantasy Mercator style image and project it then I think it would be very interesting to see a post on how you do that and what images you can get from from it. I like the idea of creating the one image and being able to specify the angle on the planet to look at it. It sounds like you can do that with command line for dynamic web pages.

Thank you Redrobes.
Xplanet specializes in astronomically precise renders of solar system bodies and spacecraft orbital positions using JPL ephemeris. Its use in The Cartographers Guild would be as a novelty. It can however, remap Plate-Carreé to almost any other projection with insanely precise maths. With the use of MMPS (Matthew's Map Projection Software) it can render a Mercator fantasy map into a realistic planet or moon for illustrations and box art.
Post a fantasy mercator without devices and specify the upper and lower polar latitudes, and I will post a pretty picture along with the procedure.

*clouds, upper atmosphere scattering, ocean reflections, shadows from bump maps, orbiting moons, city lights on night side, accurate background stars and other bodies, etc.

-- Molly J.

[MollyJ]

Yeah, I use World Creator (not free) for generating random terrain data to work with as a height map and make planet surface textures. However, Gaea has a free version as I understand, it might be something you'd enjoy.

Thank you Tiana, can you post a link to gaea please? Google keeps sending me to dialysis machines.
-- Molly J.

[Redrobes]

Cool - I might just take you up on the offer. I'll see what I can dig up.

In the meantime - my google foo turned up this link for gaea:
https://quadspinner.com/


Edit: Actually for that world why not have a go at our community world. Every now and again we have a blast where we all pile into one big map and we each map a little bit of it so that the world is a quilt of different styles and therefore not very realistic but its kinda fun and you can chat with your neighbours about what is happening in your allocated zone.

If you head to:
https://www.cartographersguild.com/s...ad.php?t=33728

It lists all of the people who have participated and I attempt to keep a 4K mercator style map up to date of the ongoing and finished maps within which at time of writing is:

https://www.cartographersguild.com/a...6&d=1610625037

So I know its not realistic but I would like to see the process and we can see if anyone else has some more complete Mercator style maps done of a whole world. I have done a realistic Middle Earth but its not the whole world just a bit of it so not really any good.

Theres a slippy / leaflet map of the guild world with a lot more detail on it but that is made up of lots of tiles so you cant download it all as one big image. I could get a higher res version tho I think its the process more than the result that is interesting.

https://www.cartographersguild.com/l...ype=guildworld

Oh and I should add that you can just take your best shot and pick some suitable latitude values since the top and bottom of this world is all sea.

[MollyJ]

To convert any Fantasy Mercator to Plate-Carree ready for further projections using MMPS and Gimp;
This is assuming the map limits are Latitude 85-S to 85-N

Gimp is well known.
MMPS is "Matthews Map Projection Suite". It is free and available at:
http://www.users.globalnet.co.uk/~arcus/mmps/

STEP 1
Gimp: "crop out the margins and save as world_merc.ppm (portable pixmap format)"

STEP 2
MMPS/project: "This is the first stage. Decide Width (-w) of the image here. Height (-h) is half the width."
project -i mercator -adjust -w 8192 -h 4096 -f world_merc.ppm > world_latlon.ppm
world_latlon.ppm has black bands where the polar regions ought to be so it's back to gimp.

STEP 3
Gimp: Paste ocean colours over the black bands, then use a nice gritty white brush across the top and bottom edges to make your polar caps.
Polar caps hide flaws nicely.


xplanet uses 6 Plate-Carree images to render planets
1 Day surface
2 Night surface with city illumination
3 Bump relief
4 Ocean/waterfeature reflectivity
5 Atmosphere light scattering
6 clouds

The xplanet command looks like this:
xplanet -window -config cartographersguild -geometry 1600x800 -lat 20 -localtime 19.00 -range 200 -radius 40 -output WORLD.jpg

I created this image (WORLD.jpg) rather without too much attention as it is just a demo.
I don't have bump maps for this world so it looks very flat. It would otherwise cast nice shadows at the terminator. I also lacked a proper night/city-light image. I dimmed it out and sprinkled some "cities" in. Since this is a political map, the colours make it look a bit wierd too.

I hope the uploaded image shows up in the proper place.

[Redrobes]

Wow yes thats brilliant. Don't worry about the lack of textures in this case, I am sure there are people here on the guild with a much better atlas and maybe they could be tempted to draw a night / clouds maps etc to make up the full set and then they would be able to unleash the power of the app.

Can I ask what was in the -config cartographersguild file ? I am guessing its a list of the textures to use.

If these results are something we can generate via cgi or command line then we could have cron generate an hourly picture for a website and then it would be dynamic at the time you look at the web page. I like that idea very much.

[MollyJ]

Hello Redrobes,

Yes, the -config file is just a list pointing to the various image files along with which set of features to toggle on/off. All of which would be accessible via command line.
Xplanet is commonly used as a backend map generator creating images dynamically as incoming data changes.

Your idea is perfectly achievable as mmps, Xplanet, and Imagemagick, can all work together in some simple shell scripts to make instantaneous updated renderings.
Night, clouds, and specular maps can all be automated so long as the ocean colour is unique and locked in. The relief map and citylights would be the only separate images.
I might play with the image myself a little next Sunday. Just to see how small a script can automate the whole process. A skilled coder would far surpass anything I bang out though.



-- Molly J.
P.s.
Would you message me. I have a question about posting bug reports on the forum.

P.p.s.
It just occurs to me now that the oceans would never change, so the spec map only needs creation once.

[MollyJ]

I'm having trouble with the message client, it shows zero sent messages.Maybe I don't have sending privs yet?
So here is my solution to Naeddyr's excellent gmic script:


Naeddiyr's G'mic plugin is a joy to work with. No more going back and forth with other applications.

The file downloads just fine. It doesnt run unless the following edits are made.

PROBLEM-1:
~/.gmic file is ignored by gimp

FIX:
In ~/.gmic, Find and Replace all (127 of them)
#@gui >> #@gimp

PROBLEM-2:
Opening an equirectangular image and applying "Rotate Equirectangular Map" in any or no axis leads to this error window message-
*******************************************
*** Error in ./rotate_equirectangular_map/*
*** Unknown filename 'keep[-1]'. *
*******************************************

FIX:
In ~/.gmic,
LINE 122 -- changed "keep[-1]" to "-keep[-1]"
LINE 197 -- changed "keep[-1]" to "-keep[-1]"

The lines look like this:

--- Keep the last (. = [-1] image index) image generated
+++ -Keep the last (. = [-1] image index) image generated

That pesky minus sign is missing from the "keep" filename