6
$\begingroup$

My first time posting, but I've already learned a lot from lurking around here over the last week, so thanks all.

For my first project I wanted to model the earth 100 million years from now based on the youtube linked: https://www.youtube.com/watch?v=uGcDed4xVD4

I started by projecting an equirectangular displacement map (white continents, black oceans) onto a globe, and then extruding the continents with a displacement modifier. I then sectioned the continents from the globe using a boolean difference modifier with a second globe just-about the same size, leaving me with a loose continent "skin". I seperated the continents into individual objects, rigged them and moved the continents, and voila:

enter image description here

And that's where I'm stuck. I want to unwrap this new earth and create a new equirectangular world-map from it, but for the life of me I can't figure out how. Straight unwrapping it isn't working. I suspect the combined geometry of the raised continents and globe and everything is just too complex. I've tried simplifying things using decimate, I've tried dissolving and otherwise cleaning up, I've even tried shrink-wrapping another globe over the model and using THAT instead, but I can't seem to get rid of the shrinkwrap "stretch lines" around the raised areas.

I'd appreciate any advice. I'm new to blender and to 3d in general, so my understanding of modelling is limited to what I could glean from forum posts and youtube tutorials - I expect there are much better ways to solve this problem than how I went about it.

Here is a .blend containing the model as far as I've managed to take it:

Note: Each face on the sphere is 10 degrees by 10 degrees, but I've added a cylinder each at 0 latitude and 0 longitude for convenience. I left them out of the model I tried to unwrap.

Thanks lots.

$\endgroup$
1
$\begingroup$

Set camera to side view, press "u" and select "Sphere Projection".

enter image description here

If you want PRECISE equirectangular projection, you'll need to write a script that generates uv coords based on vertex position. Shouldn't be too difficult, seeing that your geometry is normal sphere.

$\endgroup$
  • $\begingroup$ For some reason I'm not having any joy on my side following your instructions. Is it possible that the UV/Image Editor window to be set to not show the unwrap even though it has done it? If I could get it to this point I'd be happy, 'cause then I can just fiddle with the sphere's top and bottom vertices to get a proper equirectangular unwrap. $\endgroup$ – geekgrrrl May 26 '15 at 17:57
  • $\begingroup$ When I open the UV/Image Window, instead of getting the standard square grid the unwrapped faces usually appear on, I get something that looks like it's terribly zoomed in, then when I zoom out what's displayed is a plane with a single lateral and vertical line bisecting it. Don't know if that helps. I tried unwrapping a plain cube and sphere in a different project file and those work just fine. #confused $\endgroup$ – geekgrrrl May 26 '15 at 18:06
  • $\begingroup$ Looks like it IS a blender setting of some sort that was tripping me up - I copied the entire model out into a new project file and now it's projecting. I'm still not sure what might have caused this so if anybody knows I'd appreciate a heads-up for next time. THANKS SigTerm. :-) $\endgroup$ – geekgrrrl May 26 '15 at 18:19
  • 1
    $\begingroup$ Basically, you normally might want to create blank texture image in image editor (it should work without that), and unwrap only shows up when you're in vertex/face edit mode and have things selected. I don't know what could've been causing trouble, because I used your file to make this screen. Please note that I have no idea which spherical projection is used in spherical unwrap (It might not be "equirectangular" one), so if you need something specific/precise, research writing python scripts to generate uv coordinates. $\endgroup$ – SigTerm May 27 '15 at 8:30
  • $\begingroup$ Yeah I think you're right that this is going to require scripting. The unwrapping/sphere projection works, but for the life of me I can't get a useable map from it. The distortion is just too much no matter what I do. I suspect it's mostly because the continents are really seperate objects (which I joined previously) floating on top of the sphere, and blender is trying to compensate. A single object with just rectangles on it would probably unwrap better, but after trying shrinkwrap, remesh, decimate etc I'm still stuck, so scripting it is I guess. Thanks again for the feedback SigTerm $\endgroup$ – geekgrrrl May 28 '15 at 10:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.