Have managed to load a large height-map image and generate a “mini-map” of it and setup the map generation menu:
As the screenshot shows, the original file is 8192×8192 pixels, in 16-bit gray-scale.
Also populated drop-down boxes to select the “world” size in tiles across and the size of each tile, also there is a list to set the maximum height of the generated world. All in “world units”
Next is to link the drop down boxes to change the “pixels to unit” scale value and also to lock the sliders on the left to keep each one less than the one below it (they are there to set the height percentage for painting the one to four textures based on the terrains height during tile generation)