As far as I can tell, the way surfers measure wave heights can be all over the map. After thoughtful consideration, it has been determined that they can be roughly subdivided into four categories.
1) The Hawaiian Method. The Hawaiians measure wave height from the back of the wave. This method results in an under-estimation of most surfers' idea of how wave height should be measured, probably because surfers ride the front of the wave, not the back. If one uses that method, the epic wave in the thumbnail might only be a 10-15 footer. This method is for the Manliest of the Manly.
2) Wave Height = Face Height. This method seems the most intuitive since, as mentioned above, surfers ride the face of the wave. Plus, this is the view seen from the beach and it's the method that most accurately jibes with descriptions from wave cams, surf reporters, beachgoers, surf photographers or dudes checking things out from the parking lot. Using this method, a 5 foot wave is about equal to the height of a dude standing on his surfboard.
3) the buoy method. The wave heights are equal to the number of feet reported by the buoy, no matter what the waves look like when they get to the beach. The Beard is a disciple of this method with the proclamation, "the buoys don't lie".
4) the lkilpatrick method. This method is used to calculate waves which are X times overhead (the dimension 'foot' is completely discarded). Using this method, the top of an OH wave is as tall as a dude lying on his surfboard paddling out. A 3X OH wave is 3X as tall as the dude lying on his board. Surfers (and some non-surfers) use this method when attempting to impress chicks at bars, non-surfing friends, relatives and co-workers gossiping at the water cooler.
Which method do you use?