Module 1 - Visual Interpretation

In this laboratory exercise, the focus was on the interpretation of features observed in aerial photographs, examining both black and white and color imagery. 

In Exercise 1 of the lab I had to identify and interpret features present in black and white aerial photography, with a focus on the concepts of tone and texture. In this context, tone refers to the range of brightness and darkness within an image, contrasting with color photography, where tone is described using hue, saturation, and brightness. Texture indicates the variations in tone across a surface, resulting from the arrangement and repetition of these tones or colors. It can be classified into various categories, including very fine, fine, mottled, coarse, and very coarse. To achieve the exercise's objectives, I initially analyzed tone by mapping areas with distinct brightness levels, using polygons to outline each defined zone. Similarly, for texture assessment, I identified various textures and outlined areas with similar characteristics using polygons. This systematic approach facilitated a clear interpretation of the aerial imagery, highlighting the key characteristics of tone and texture.

In Exercise 2 of the lab we are required to identify features in black and white aerial imagery by employing four criteria: shape and size, shadow, pattern, and association. Each feature is marked with distinct points, utilizing different colors or symbols per criterion. The author successfully identified three objects based on shape and size characteristics: a commercial building, a road, and a swimming pool. Furthermore, three features were recognized through shadow analysis: a tree, a utility pole, and a water tower, identifiable by their shadows. Additionally, the association criterion was applied to identify three objects in relation to their surroundings, including a pier, a single-family house, and a hotel building. Finally, utilizing the pattern criterion, defined as the spatial distribution of objects across the terrain, the author identified two features: water and sand.

In exercise 3 of the lab we interpret color information by using a true color TIFF file and subsequently comparing the identified colors with those in an infrared image of the same geographical area. The process involves selecting five specific features from the true color image, denoting each feature with a point, and documenting their corresponding colors in a predefined table. The features identified for this exercise include a river, a forest located to the southwest of the river, marshes situated in the northeast portion of the image, grass found in a golf course, and a water basin. Following this, a color comparison of the same features in the infrared images is conducted, with results also recorded in the same tabulated format. This exercise aims to enhance the understanding of how different imaging techniques can represent environmental features across various spectral ranges.

Color-infrared (CIR) aerial photography, or "false color" photography, is utilized for natural resource interpretation, unaffected by atmospheric haze. Live vegetation typically displays red tones, with intense reds indicating healthy growth and lighter shades signaling reduced vigor. Bare soils are depicted in shades of white, blue, or green, generally darker indicating moisture levels. Man-made features reflect their materials, with asphalt appearing dark, gravel and dirt roads lighter, and concrete light-toned. Water is represented in varying blues, from nearly black for clean water to pale blue for sediment-rich areas, with shallow stream colors influenced by bottom materials like sand.