I've seen some pretty tall sunflowers. We had neighbors growing up who had some that were probably around 10 feet, and I thought that was tall, but this one is so much taller! http://abc13.com/weather/gardener-grows-worlds-tallest-sunflower/777369/
I like the way the used the scoffold to relay the true height of the plant. To say the plant is ten feet tall is one thing but then show it this way really shows you how tall the plant is.
The picture of the "sequoia" sunflower reminded me of the sequoia fold out in NG Magazine. It used people to show the scale.