What are the advantages and disadvantages of visual interpretation of remote sensing images

Visual interpretation is based on human experience and knowledge, through the color and shape characteristics of the image and the interpretation of the signs to identify the target or object. Visual interpretation is an irreplaceable part of remote sensing applications, and it has coexisted and complemented geoscience analysis methods for a long time. However, visual interpretation has its limitations, such as the inability to organically combine remote sensing and GIS, and the difficulty of updating.

1. In high-resolution remote sensing images, the spectrum of plants is used to distinguish vegetation types, and the types of trees, shrubs, and grasslands can be directly determined.

Herbaceous plants show a large uniform hue on the high-resolution remote sensing image, but because the herbaceous plants are relatively low and cannot see the shadows, they will not show a large uniform hue.

2. According to the thermal infrared image interpretation signs, the woodland is dark gray to gray-black during the day, light gray at night, and the grassland is black or dark gray at night.

3. According to the TM plus color synthesis, the woodland is dark red, the mountain has a strong sense of the body, the ridge is red with black tones, and the grassland is purple patches and strips.

Principles of visual interpretation of remote sensing images.

In remote sensing images, different features have different features, and these image features are the basis for interpreting and identifying various features, which are called interpretation or interpretation signs. Interpretive signs include direct and indirect interpretive signs:

1 Direct Interpretation of Signs (1) Shape The shape of an image refers to the general form of an object or its reflection on its contours. Various objects have a certain shape and characteristic radiation properties. The same kind of object has the same gray scale characteristics on the image, and the distribution of these pixels with the same gray scale on the image constitutes a similar shape to the object.

As the scale of the image changes, the meaning of "shape" also varies, in general, the geometry of the object itself is represented on the large scale image, while the distribution shape of the same type of object is represented on the small scale image. The shape of some objects is very special, and its plane shape is an important sign of the structure, composition and function of the object, and sometimes even the key, so "shape" is an important tool for interpretation.

2) The size of the large and small objects on the image is also one of the interpretation signs. The meaning of "size" varies depending on the scale of the image: on a large-scale image, the size of a single object is measured, while on a small-scale image, only the size of the distribution of the same type of object can be measured.

3) Colors and tones.

Color generally refers to color images, and with the development of color photography and false color synthesis technology, the difference in color can further reflect the subtle differences between features and provide more information for interpreters. The human eye has a long ability to distinguish colors.