The main elements of visual interpretation are: tone, shape, size, pattern, texture, shadow, , association. Tone refers to the relative brightness or colour of objects in an image. It depends on the spectral properties of an object. Variation in tone allows to distinguish elements of different shape, texture and pattern. Shape refers to the general form, structure, or outline of individual objects. Straight and sharp edge shape represent typically the anthropogenic features i.e. urban or agriculture, the natural features like rivers, wetlands are more irregular in shape. Size of objects in an image is a function of scale and it depends on the spatial resolution of the image. The assessment of the size of the target’s object in relation to other objectives as well as an absolute size of the object are the important part of the interpretation. Pattern refers to the spatial arrangement of objects, i.e. network of street and houses in an urban area, orchards with the line of trees. Texture refers to the arrangement of frequency of tonal variation in particular areas of an image. Rough texture would have very large, coarse tonal variation (e.g. forest canopy), whereas smooth texture very little tonal version (e.g. uniform, homogenous surfaces). It depends on the size, shape and pattern of objects. Shadow depends on the scale and spatial resolution of an image. Shadow is useful to measure the height of an object, to distinguish the coniferous from broadleaf trees. In the radar imagery is useful for identifying topography and landforms. Association refers to the relationship between objects and features in proximity to the target interest.
Identify physical, semantic and spatial properties used to assigned objects to the target classes
Completed