What does the term 'positive' refer to in aerial photographs?

The term 'positive' in the context of aerial photographs typically refers to an image that accurately represents the scene as it appears in reality, where light areas in the photograph correlate to light areas in the actual scene, and dark areas correspond to dark areas. This is fundamentally different from a negative image, where colors and brightness values are inverted.

A positive image provides an accurate portrayal, making it easier for interpretation and analysis, which is crucial for surveying and mapping purposes.

While other options present different concepts related to photography, they do not directly relate to the definition of a 'positive' image in aerial photography. For instance, mentioning a photograph printed on a glass plate does not align with the conventional understanding of positive imagery, which is more about the resulting image quality rather than the medium or method of printing.