When I was working on our Procedural Landscape Generation assignment, I
noticed that there aren't many free and realistic skyboxes on the web (or I didn't search good enough). Anyway, I ended up with rendering my own. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. If that license does not fit to your purposes, please contact me. And if you create something beautiful with them that you would like to share, I'll be glad to receive a message :)
First an image with the skyboxes in action in the landscape generator:
Clockwise: sun5deg, sun5deg2, sun25degtest and sun45deg.
The Sky Boxes
All sides of the cubemap are 1024x1024 pixels. You can download them as PNG (just a large (4096x3072 pixels) version of the preview here) or as RAR (5 BMP's of 1024x1024 each with each face of the cubemap).
Sun altitude of 5 degrees above the horizon. More information on the bottom of the page.
PNG or RAR.
Sun altitude of 5 degrees above the horizon. More information on the bottom of the page.
PNG or RAR.
Sun altitude of 25 degrees above the horizon. More information on the bottom of the page.
PNG or RAR.
Sun altitude of 45 degrees above the horizon. More information on the bottom of the page.
PNG or RAR.
Additional Information
To properly combine the scene and skybox, the lighting conditions (and fog, if any) applied on the scene should match the skybox. For the landscape generator, I created a small data file which you can download here. It is self descriptive (I hope), and it contains information about ambient lighting, light position and color (the sun), fog color and fog density. Things like the fog density are a bit OpenGL specific, obscure and obtained by tweaking. The information about the fog and light colors were obtained using Photoshop.
