What is the detailed introduction of linear directional photogrammetry and remote sensing? 0? three

Introduction to linear directional photogrammetry and remote sensing? What is the work of linear directional photogrammetry and remote sensing? 1. Briefly describe the three stages of photogrammetry development and its role in geographic information system technology. A: The three stages of photogrammetry are: analog photogrammetry, analytical photogrammetry and digital photogrammetry. Function: The direct result of analog photogrammetry is various maps (topographic maps, special topics, etc. ), it must be digitized before it can be input into the computer. Analytical photogrammetry and digital photogrammetry can be directly used for various tasks. What are the internal and external orientation elements of aerial photographs and what are their uses? Answer: the internal orientation element of aerial photography: a parameter indicating the relative position of the photography center and the photo. External orientation elements in aerial photography: On the basis of recovering the internal orientation elements, the parameters of the spatial position and attitude of the photographic beam at the moment of photography are determined. The function of orientation elements in aerial photos is the basis of establishing three-dimensional models needed for surveying and mapping. The function of external orientation elements in aerial photos is to build a three-dimensional model. 2. Why do the corner elements in the external direction elements have three different choices? Answer: The reasons for the three different choices of angle elements in external orientation elements are: according to the design needs of different instruments. 3. What are the coordinate systems commonly used in photogrammetry? What's the use of each? A: There are two kinds of coordinate systems commonly used in photogrammetry. One is used to describe the position of the image point, which is called the image space coordinate system; The other is used to describe the location of the grounding point. It is called the object coordinate system. (1) image space coordinate system ① image plane coordinate system The image plane coordinate system is used to indicate the position of an image point on the image plane. Usually, the right-handed coordinate system is adopted, and the axis is selected as required. In analytical photogrammetry and digital photogrammetry, the image plane coordinate system is often determined according to the frame, which is called the frame coordinate system. (2) Image space coordinate system In order to facilitate the transformation of spatial coordinates, it is necessary to establish a coordinate system that describes the position of image points in image space, that is, image space coordinate system. Taking the photography center as the coordinate origin, the axis is parallel to the axis of the image plane coordinate system, and the axis coincides with the main optical axis to form the right-handed rectangular coordinate system of the image space. ③ The image space coordinates of an image point in the image space auxiliary coordinate system can be obtained directly from the image plane coordinates, but the waiting point of this coordinate is that the image space coordinate system of each photo is not uniform, which brings difficulties to calculation. Therefore, it is necessary to establish a relatively unified coordinate system, called image space auxiliary coordinate system, which is represented by. The origin of this coordinate system is still selected in the photography center. The choice of coordinate system depends on the need. (2) Object Coordinate System ① Photogrammetry Coordinate System Move the auxiliary coordinate system of the image side to the ground point P along the opposite direction of the Z axis, and the obtained coordinate system is called Photogrammetry Coordinate System ② Ground Survey Coordinate System. The coordinate system of ground survey usually refers to the map projection coordinate system, that is, the Gauss-Kruger belt or the plane rectangular coordinate system with projection and height system used in national surveying and mapping. The spatial rectangular coordinate system formed by them is the left-handed system, which is represented by. (3) Ground photogrammetry coordinate system Because the photogrammetry coordinate system is right-handed and the ground photogrammetry coordinate system is left-handed, it brings difficulties to the transformation from photogrammetry coordinate system to ground photogrammetry coordinate system. Therefore, a transitional coordinate system is established between photogrammetry coordinate system and ground survey coordinate system, which is called ground photogrammetry coordinate system, and its coordinate origin is one of the ground points in the survey area. 4. In photogrammetry, why do we often convert the image space coordinates into the image space auxiliary coordinate system? What is the commonly used coordinate transformation formula? Answer: When calculating the image space coordinates of an image point from the image plane coordinates, the image space coordinates of each photo are not uniform, which brings difficulties to the calculation. So as to establish a relatively unified image space auxiliary coordinate system. The transformation relationship between the image space coordinate system and the image space auxiliary coordinate system is 5. What is * * * line equation and its application in photogrammetry? A: The * * * line equation is the * * line equation, that is, the image equation of the central projection * * line equation includes twelve data: the coordinates of the image point with the main image point as the origin, the coordinates of the corresponding ground point, the main distance of the photo and the external orientation elements. The main applications of * * line condition equation in photogrammetry are: single-chip back intersection and three-dimensional model space front intersection; ② Find the coordinates of the bottom point of the image; ③ Basic equation in beam adjustment ④ Digital projector in analytical plotter; ⑤ Aerial simulation; ⑥ Drawing a single photo with DEM. 6. What is the post-rendezvous in space for? There are several unknowns in this solution. At least several ground control points need to be measured. Why? Answer: Using a certain number of ground control points, according to the * * * line equation, the external orientation elements of a photo are obtained in reverse. This method is called the spatial back intersection of a single photo. When solving the external orientation elements, there are six unknowns and at least six equations are needed. Because each pair of yoke points can list two equations, if there are three known ground coordinate control points, six equations can be listed to solve six external orientation element corrections. In order to improve the accuracy, there are often redundant observation equations. In the space back intersection, four or more ground control points are usually selected at the four corners of the photo, so the least square method is used for adjustment calculation. Homework 3 1. What is artificial stereoscopic vision? What are the three basic conditions for observing stereo? Answer: Artificial stereoscopic vision is to construct a spatial scene on photosensitive materials, and then observe the constructed photos with human eyes to produce physiological parallax, so as to reconstruct the stereoscopic vision of the spatial scene. The seen scene is called stereoscopic image, and the generated stereoscopic vision is called artificial stereoscopic vision. The three basic conditions for stereoscopic observation are: 1: Two photos must be stereo pairs of the same scene taken in two different positions. 2. Two eyes must only see one pair of photos. 3. The line of the same scene (the same name image point) in two photos should be roughly parallel to the eye baseline. ы 2. What are the three methods to measure the three-dimensional coordinates of ground points by double-image analytical photogrammetry? Answer: There are three commonly used methods to analyze stereo image pairs: 1, and the spatial coordinates of ground targets are calculated by using the spatial back intersection and front intersection of photos. 2. Using stereo images to orient the inherent geometric relationship relatively, establish a stereo model similar to the ground, and calculate the spatial coordinates of the model points. Through absolute orientation, the model is translated, rotated and scaled, and the model is brought into the specified ground coordinate system to obtain the absolute space coordinates of the ground target. 3. The spatial coordinates of the ground target are calculated by using the double-image analytical photogrammetry of the beam method. In this method, the error equations of the points to be solved and the control points of the known field are listed at the same time, and the adjustment solution is unified. This method is strict in theory. It combines the two steps of the first two methods into one. 3. What is the purpose of analyzing relative orientation? What are the two ways? How many direction elements are there in each method? Answer: Objective: To restore the external orientation elements of the two photos in the stereo image pair, that is, to restore their absolute position and posture, and to reconstruct the absolute stereo model of the ground being photographed. The two methods are: 1: relative orientation elements of continuous image pairs. The five directional elements are: 2. A single image pair is relative to a directional element. These five directional elements are: 4. What is the purpose of analyzing absolute orientation? What are the direction elements? How to find the absolute direction element? How many ground control points are needed in the solution? Answer: The purpose of absolute orientation is to convert the photogrammetric coordinates obtained after relative orientation into ground survey coordinates and seven parameters. Seven unknowns require at least seven equations. If the ground control points with known plane coordinates () and elevation are called leveling control points, only the control points with known elevation are called elevation control points. At least two leveling control points and one elevation control point are required, and the three control points cannot be in a straight line. In production, four control points are generally arranged at the four corners of the model, so there are redundant observation values, which are solved by least square adjustment. 5. What are the analysis methods of aerial triangulation? A: Analysis of air triangulation with air belt method Firstly, each image pair in the air belt is relatively oriented by continuous method, and a three-dimensional model is established. Then, the four known control points in the navigation belt or the common points of adjacent navigation belts are used to make the absolute orientation of the navigation belt model, and all the navigation belt models are connected into a regional network to obtain the coordinates of all the model points in the unified ground photogrammetry coordinate system. Finally, the nonlinear correction of gas zone or regional network is carried out. The correction method is that each band has its own set of polynomial coefficient values. Then, under the condition that the calculated coordinates of control points should be equal to the measured coordinates and the common point coordinates of adjacent bands should be equal, the polynomial coefficients of each band should be obtained under the condition that the sum of squares of errors is minimum. Coordinate correction, and finally get the ground coordinates of the encryption point. The second is to analyze aerial triangulation by independent model method, which is based on the independent method of relative orientation to establish a single three-dimensional model. Because the auxiliary coordinate system and scale of each model image space are inconsistent, the known control points in the model and the common points in the model should be used for spatial similarity transformation. Firstly, each single model is regarded as a rigid body, and a region is connected by the common points of each single model. In the process of connection, each model can only be translated, rotated and scaled, which is accomplished through the spatial similarity transformation of a single model. During the transformation, the coordinates of common points between models should be equal, the calculated coordinates of control points should be equal to the measured coordinates, and the sum of squares of errors should be minimum. Under these conditions, seven absolute azimuth parameters of each model are obtained by using the principle of corrected least squares. So as to find the ground coordinates of all encryption points. Thirdly, the beam method is used to analyze aerial triangulation. This method takes each photo as a unit, based on the * * * line equation, establishes the unified error equation and normal equation of the whole region, and solves the six external orientation elements of each photo in the region and the ground coordinates of all points of the required solution as a whole. Its principle is the double-image analytical photogrammetry with beam method. 6. What are the advantages of 6.GPS-assisted aerial triangulation? Try to describe its basic principle. Answer: The advantage is that GPS differential positioning technology can obtain three-dimensional camera coordinates with sub-meter accuracy, which is effectively used for regional network difference. The calculated coordinate accuracy of encryption point is better than that of GPs camera, which can meet the encryption specifications of various scale mapping. In an area, if there are no signal discontinuities such as out-of-lock and cycle slip in GPS observations, GPS station coordinates can completely replace ground control points for regional network adjustment without considering the benchmark. ③ In order to solve the benchmark problem and effectively correct the GPs system error caused by cycle slip and lock loss, it is necessary to increase the flight path or add a few ground control points. (4) A large number of experimental results show that GPS-assisted aerial triangulation can be used for the adjustment of joint stations with different photographic scales and different areas, and can be put into production and practical use.