I visited Yankton, SD in late 2018 to camp out and get up early for the sunrise, which was spectacular. The mission,however, was to accurately lay out a view of the spillway, in perspective. You can see my scaled viewfinder on the easel below.
I have since found the math to calculate perspective but this scene was scaled by finding key points in the viewfinder and plotting them on the canvas. The canvas is 18″ x 24″ and I set my viewfinder at 3″ x 4″ (dividing by 6 or using a ratio of 1:6) so the picture would fit exactly with the view I was seeing through the viewfinder:
It was too cold to continue beyond collecting key points and gathering good reference photos. Back in the studio, I drew, and fixed and drew the scene until I had a enough information to begin the painting. One of the reference photos I used was a U.S. Army Corps of Engineers photo taken of the spillway at full release!
While this wasn’t exactly my viewpoint, I could place the hydraulic jump (the wave) where it would be in my drawing. With the drawing ready, I began my watercolor. The Aquabord takes pencil and watercolor washes very well. I have been able to correct the painting and even take small areas of the canvas back to original white.