I'm not entirely clear what you want to do. Are you trying to export a terrain, or textures? If you're trying to get the terrain out, you would feed your Fractal Terrain into another Heightfield Generate Shader input (before the Compute Terrain), set the sizes in the node settings (size in meters and size in pixels, e.g. resolution), and then click Generate, then Right-click and Save As to save as TER or OpenEXR.
So basically the 2nd Heightfield Generate is acting as a converter to you Power Fractal Terrain. Since the Power Fractal comes after the initial Heightfield Generate, its influence will not be seen if you save that first Heightfield Generate output. The network goes from top to bottom, basically. So that's what the 2nd Heightfield Generate is for, capturing the influence of the later shaders in the chain.
- Oshyan