Wiktionary
picture plane
n. In art, the imaginary plane correspondent with the physical surface of a drawing, painting or print.
WordNet
picture plane
n. the plane that is in the foreground of a drawing or painting; coextensive with but different from the objective surface of the work
Wikipedia
Picture plane
In painting, photography, graphical perspective and descriptive geometry, a picture plane is an imaginary plane which is located between the "eye point" or oculus and the object being viewed and is usually coextensive to the material surface of the work. It is ordinarily a vertical plane perpendicular to the sightline to the object of interest.
Usage examples of "picture plane".
And, of course, there was a lot of blank picture plane left to cover.