What Is Image Reconstruction?

A technique for obtaining shape information of a three-dimensional object through digital processing of data measured outside the object. Image reconstruction technology began to be applied in radiological medical equipment, displaying images of various parts of the human body, namely computer tomography technology, or CT technology for short, and it has gradually been applied in many fields. There are mainly projection reconstruction, light and shade restoration shapes, stereo vision reconstruction and laser ranging reconstruction.

A technique for obtaining shape information of a three-dimensional object through digital processing of data measured outside the object. Image reconstruction technology began to be applied in radiological medical equipment, displaying images of various parts of the human body, namely computer tomography technology, or CT technology for short, and it has gradually been applied in many fields. There are mainly projection reconstruction, light and shade restoration shapes, stereo vision reconstruction and laser ranging reconstruction.

Chinese name

Image reconstruction

Foreign name

image reconstruction

Applied discipline

Communication

Image reconstruction image information

1.1 Projection reconstruction

The X-ray and ultrasonic waves are used to transmit the perspective projection view of the obstructed object (such as the internal organs of the human body and the underground ore body) to calculate the tomogram of the restored object. Reconstruct the shape of an object using a tomogram or directly from a two-dimensional perspective projection of the object. This reconstruction technique uses a certain type of radiation to irradiate different rays when they pass through the tissue, causing different projection intensities on the imaging surface. The inversion obtains an image of the internal distribution of the tissue. X-ray CT technology applies this kind of reconstruction and provides a means for medical diagnosis. Projection reconstruction is also used for geological exploration. In the detection well, ultrasound is used to transmit ultrasound, and related instruments are used to receive ultrasound reflected from different formations and ore bodies. According to the transmission and reflection laws of ultrasonic waves in the medium, the transmission projection map obtained by the related technology is used for analysis and calculation, and the shape of the ore body buried in the ground can be restored and reconstructed.

1.2 light and dark restore shape

A single photo does not contain the depth information in the image. The reflection model of the light on the surface of the object can be used to analyze and calculate the image gray data to restore the shape of the object.

The imaging of an object is determined by factors such as the distribution of light sources, the shape of the surface of the object, the reflection characteristics, and the geometric position of the observer (camera, video camera) relative to the object. Computer graphics can be used to generate images at different viewing angles. Applied in computer-aided design, it can demonstrate the shape of the design object viewed from different angles, such as house construction, mechanical parts, clothing modeling, etc. The reverse processing can calculate the three-dimensional shape of the object based on the brightness of each pixel in the image, and empirically assume the distribution of the light source, the reflective properties of the surface of the object, and the geometric position at the time of imaging. This reconstruction method has complicated calculations and a large amount of calculations. At present, it is mainly used for terrain reconstruction in remote sensing images.

1.3 Stereo vision reconstruction

Use two cameras (or video cameras) to take two photos (or video images) of the same scene on the left and right sides, use the stereo vision model of binocular imaging to restore the shape of the object, and extract the three-dimensional information of the object, also known as three-dimensional image reconstruction. This method is an imitation of human vision. First, the edges, corners and other features of the object are extracted from the two images. Because the positions of the same edges and corners of the object are slightly different in the two images due to the stereo disparity, the corresponding lines and corresponding points in the two images are found after matching processing, and the shape of the object is obtained by geometric coordinate conversion. Mainly used in the field of industrial automation and robotics, and also used in map mapping.

1.4 Laser ranging reconstruction

The scanning laser is used to measure the object to obtain the three-dimensional data of the object. After the coordinate conversion, the three-dimensional shape data of the object is restored. Laser ranging is characterized by accuracy. One method is to fix the laser source, rotate the object, and lift it up and down to record the three-dimensional data of the object in various sections and reconstruct the image of the object in various directions. Another method is to use a laser source to scan forward in a cone area. Obtain 3D data of the object in front. This method is applied in walking robots, which can find obstacles in front, calculate the area of obstacles, and walk around. Image reconstruction has also gained important applications in the communication field. For example, image reconstruction technology is used to obtain very intuitive three-dimensional spatial distribution images of radio field strength. Image reconstruction technology for face image transmission through extremely high compression ratios can restore the original image at the receiving end. Face image.