You can use our render_skybox Python script from http://michalis.ii.uni.wroc.pl/cge-ww... to render six matching images from Blender ( http://blender.org/ ) to capture the environment.
These images can be immediately used as a skybox, or a cubemap environment map (for reflections on any curvy object). They are useful in Castle Game Engine ( http://castle-engine.sourceforge.net/ ), or actually in any VRML / X3D viewer.
The script and sample X3D files are available in our "cge-blender" GitHub repository on https://github.com/castle-engine/cge-... .
To learn how to model such landscape in Blender, see e.g. • Creating a mountain landscape in blender