What is an aerial photograph?

Aerial photos are aerial photos, also called aerial photos. Generally refers to all kinds of remote sensing photos taken by aerial photography equipment. There are many kinds. According to the camera structure and imaging mode, it can be divided into frame type, panoramic type and continuous shooting type. Frame aerial photos can be divided into small frames according to the frame size, such as 70×70 mm2；; There are 23 kinds of standard picture frames, such as 18× 18cm2, 23× 23cm2, and large picture frames are 23× 46cm. According to the attitude of the camera at the moment of exposure, it can be divided into vertical photography, oblique photography and vertical photography. According to the image scale, it is divided into ultra-small scale, small scale, medium scale, large scale and super-large scale. According to the photosensitive characteristics of photosensitive film, it can be divided into panchromatic, color, panchromatic infrared, color infrared and multi-band aerial photographs. Among them, panchromatic, panchromatic infrared, single-band and multi-band are all black and white aerial photos; There are two kinds of color aerial photographs: natural color and approximate natural color synthesized by multi-band film; Color infrared and false color photos synthesized by multi-band film are false color photos. As far as use is concerned, the panchromatic black-and-white aerial photographs taken by the framing camera are mainly used for topographic mapping, while other aerial photographs are mostly used for various thematic interpretation and mapping. Satellite image is the general name of satellite remote sensing image. Satellite photos are remote sensing images obtained by observing the earth's land surface with earth observation remote sensing instruments loaded on artificial satellites. Compared with aerial photos, satellite photos have lower ground resolution and can only be used for small-scale land resources investigation. Compared with aerial photos, satellite photos have the following outstanding advantages: strong macro and wide coverage; Multi-temporal repetition, fast data update and strong current situation; Multi-band observation can reflect the spectral characteristics of ground objects; Digital recording can not only provide video products, but also provide digital products, which is convenient for computer processing for various professional purposes; The observation platform is high and the geometric distortion is small. Satellite photos made after geometric correction of computer images can be directly mapped without correction. Used for detailed land investigation, it can greatly speed up the investigation progress and save money. In addition, most satellite movies can be sold publicly, without confidentiality, convenient to purchase and use, and relatively low in price. Generally, the cost of satellite films with the same area is less than one tenth of that of aerial photographs. Of course, satellite remote sensing also has its limitations, mainly low ground resolution and small mapping scale. Taking Landsat TM image as an example, resource investigation and thematic mapping can generally meet the mapping accuracy of1∶ 200 thousand. A single area and the corresponding time phase and band combination can be performed &; 127; 1 ∶ 50,000? : 65438+100000 scale survey. It can't meet the accuracy requirements of detailed land survey in agricultural areas, but it can meet the mapping accuracy requirements of semi-agricultural and semi-pastoral areas in northern and western China and areas with agriculture, forestry and animal husbandry. Secondly, satellite photos generally do not have the characteristics of stereoscopic observation, which is not convenient for stereoscopic observation and topographic mapping. However, new resource satellites such as SPOT satellite images can overcome the above two shortcomings, and their mapping accuracy can reach 1∶25000- 1∶50000. 127; Stereo observation has also been done, but the cost of SPOT satellite image data is high and it is not convenient to popularize and use. Generally speaking, aerial photographs have high resolution, clear and detailed images, rich features and easy interpretation. However, the acquisition cost of aerial photos is also high, and they belong to central projection, so the correction processing is more complicated. Generally, it is used in a local scope and produced on a large scale.