As in all painting, the first concern is light. And as with all paintings from life in a natural setting, light is time. Time is of the utmost importance since I have chosen to paint a large, fairly complex painting in overhead daylight.
To save time I photograph Heidi on location and then cover the canvas with a monochromatic wash back in my studio. This is mainly to allow me to focus on the values and colors of the finished painting when painting on location, since most of the drawing is completed.