Module 1 Lab: Visual Interpretation

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 Visual interpretation is a way of extracting features from an aerial photograph. One technique involves using visual characteristics of an image. These characteristics include size, shape, tone, texture, pattern, and shadow.

The first part of the lab involved the use of tone and texture to extract features. The tone element refers to the brightness or color of an object based on the amount of light reflected from an object. Objects that are darker have less light reflected. Objects that are lighter reflect more light. The texture element determines the visual smoothness or coarseness of the image. The variations of tone and texture elements help to bring out different features in the landscape. The map below shows the use of tone and texture to interpret features from an 8-bit aerial image.

The next part of the lab was to identify features from an 8-bit black and white image using four different criteria. The four criteria were shape and size, shadow, pattern, and association.  The size and shape of an object can help to identify features that are familiar. Objects can be identified by their association with surrounding objects. Shadows on the ground can help identify objects that are hard to distinguish from above. A group of objects in a pattern can help identify a feature that is hard to recognize by itself.




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