Since I've been skiing this has been how I've experienced all the terrain. His maps just are skiing to me. But, interestingly, with the rise of smartphones/gps apps like Slopes and the late lamented Fatmap have started to move the ski world towards 3d terrain maps and away from these artistic maps.
I have a side project I've been meaning to dust off that translated GPS coordinates to locations on Niehues maps. I got it working reasonably well but the distortions were significant enough that it needs a lot of control points to do the mapping.