Sometimes I use a sketch as a visual note to myself. Instead of trying to do a finished drawing on location I will do a quick sketch to capture an idea or impression of what I notice. I may later use the note to do a finished work instead of using a reference photo. Here are three approaches. Each one took me less than 10 minutes to draw. The first one uses line to establish shapes, structure, and proportions. The second is a tone sketch to remember the values, and the third is a color sketch to capture the local colors in the scene.