Aerial photographic and satellite image interpretation

Aerial photographic and satellite image interpretation, or just image interpretation when in context, is the act of examining s, particularly airborne and , to identify objects and judging their significance. This is commonly used in military aerial reconnaissance, using photographs taken from reconnaissance aircraft and reconnaissance satellites. The principles of image interpretation have been developed empirically for more than 150 years. The most basic are the elements of image interpretation: location, size, shape, shadow, tone/color, texture, pattern, height/depth and site/situation/association. They are routinely used when interpreting aerial photos and analyzing photo-like images. An experienced image interpreter uses many of these elements intuitively. However, a beginner may not only have to consciously evaluate an unknown object according to these elements, but also analyze each element's significance in relation to the image's other objects and phenomena. Vertical aerial photographs represent more than 95% of all captured aerial images. The principles of capturing vertical photographs are shown in Figure 2. Two major axes which originate from the camera lens are included. One is the vertical axis which is always at 90° to the study area. Another one is the camera axis which changes with the angle of the camera. To capture a vertical aerial photograph, both of these axes must be in the same position. The vertical pictures are captured by the camera which is above the object being photographed without any tilting or deviation of the camera axis. Areas in a vertical aerial photograph often have a consistent size. Oblique are captured when the cameras are set at specific angles to the land. It is a very helpful enhancement or addition to the traditional vertical image. It allows the vision to pass through a relatively high proportion of the plant cover and leaves of trees. Oblique aerial photographs can be classified into two types. Low oblique aerial photographs are generated when the camera axis has a 15–30° angle difference from the vertical axis, shown in figure 3.