Basic articles-surveying and mapping, aerial photography, photogrammetry and remote sensing

According to the current qualification standards for surveying and mapping, the second and third items are surveying and mapping aerial photography (professional sub-items are: general aerial photography, unmanned aerial photography and inclined aerial photography), photogrammetry and remote sensing (professional sub-items are: photogrammetry and remote sensing field, photogrammetry and remote sensing interior, photogrammetry and remote sensing supervision).

Surveying and mapping aerial photography refers to aerial photography installed on aircraft (aircraft, helicopters, airships, balloons, etc.). ), take a progressive view of the earth's surface from the air. Its purpose is to obtain aerial images with a certain overlap ratio within a specified range.

Photogrammetry is a science and technology to study and determine the shape, size, position, nature and relationship of the photographed object by using the images taken by optical or digital cameras. The basic principle of photogrammetry is to establish the geometric relationship between image points and corresponding object points at the moment of image acquisition.

(1) According to the research object, it is divided into topographic photogrammetry and non-topographic photogrammetry (close-range photogrammetry);

(2) According to the position of the camera station, it can be divided into: space photogrammetry, aerial photogrammetry and ground photogrammetry.

Remote sensing generally refers to the technology of telemetering the geometric and physical characteristics of objects through non-contact sensors. Simple understanding, that is, long-distance perception, mainly answers questions such as what the observation target is (qualitative), where it is distributed (positioning), and how many it is (quantitative).

Surveying and mapping aerial photography, as a means of surveying and mapping, mainly focuses on the geometric position relationship of ground objects. The main methods are photogrammetry (including airborne laser scanning and airborne side-looking radar), and photogrammetry is a data acquisition method of surveying and mapping aerial photography.

Remote sensing technology provides a variety of data sources for photogrammetry, thus expanding the application field of photogrammetry; The mature theories and methods of photogrammetry promote the development of remote sensing technology.

Aerial photography is mainly divided into film aerial photography and digital aerial camera, which has been widely used in digital aerial camera at present. Several common digital aerial cameras are shown in the following table:

Resolution of digital image: Image resolution is an important index to determine the ability of image recognition and drawing accuracy. For digital aerial images or space remote sensing images, image resolution usually refers to ground resolution.

Generally, it is expressed by the size of the ground represented by a pixel, that is, the ground sampling interval (GSD), and the unit is m/pixel. It is worth noting that the image resolution does not represent the smallest size that can identify ground objects from images.

The difference between satellite photos and aerial photos: satellite photos: large format, small distortion, low cost, fast update and low resolution.

Satellite image interpretation: three aspects of information of remote sensing images are obtained: the size, shape and spatial distribution characteristics of target objects, and the dynamic characteristics of target objects.

There are two methods, one is visual interpretation, and the other is computer digital image processing.

The next commercial remote sensing satellite data