What Is 3D Reconstruction?

The English term name for 3D reconstruction is 3D Reconstruction.

The English term name for 3D reconstruction is 3D Reconstruction.

Three-dimensional reconstruction refers to the establishment of mathematical models suitable for computer representation and processing of three-dimensional objects. It is the basis for processing, manipulating, and analyzing its properties in a computer environment, and it is also the key technology for establishing virtual reality that expresses the objective world in computers.

Chinese name

Three-dimensional reconstruction

Foreign name

3D Reconstruction

Types of

mathematical model

Field

computer

Introduction to 3D reconstruction

The English term name for 3D reconstruction is 3D Reconstruction.

Three-dimensional reconstruction refers to the establishment of mathematical models suitable for computer representation and processing of three-dimensional objects. It is the basis for processing, manipulating, and analyzing its properties in a computer environment, and it is also the key technology for establishing virtual reality that expresses the objective world in computers.

In computer vision, three-dimensional reconstruction refers to the process of reconstructing three-dimensional information from single-view or multi-view images. Because the information of a single video is incomplete, three-dimensional reconstruction requires the use of empirical knowledge. Multi-view three-dimensional reconstruction (similar to the human double (Eye positioning) is relatively easy. The method is to first calibrate the camera, that is, calculate the relationship between the camera's image coordinate system and the world coordinate system. Then use the information in multiple two-dimensional images to reconstruct three-dimensional information.

Object 3D reconstruction is a common scientific problem and core technology in the fields of computer-aided geometric design (CAGD), computer graphics (CG), computer animation, computer vision, medical image processing, scientific computing and virtual reality, and digital media creation. There are two main methods for generating three-dimensional representations of objects in a computer. One is the use of geometric modeling software to generate three-dimensional geometric models of objects under human control through human-computer interaction, and the other is to obtain the geometry of real objects through certain means. The former technology has been very mature. Several existing software support, such as: 3DMAX, Maya, AutoCAD, UG, etc., they generally use curves and surfaces with mathematical expressions to represent geometric shapes. The latter is generally called the three-dimensional reconstruction process. The three-dimensional reconstruction refers to the mathematical process and computer technology of recovering three-dimensional information (shape, etc.) of an object using two-dimensional projection, including data acquisition, pre-processing, point cloud stitching, and feature analysis.

3D reconstruction steps

Steps for 3D reconstruction

(1) Image acquisition: Before performing image processing, first acquire a two-dimensional image of a three-dimensional object with a camera. Illumination conditions and the geometric characteristics of the camera have a great impact on subsequent image processing.

(2) Camera calibration: The camera calibration is used to establish an effective imaging model, and the internal and external parameters of the camera are solved, so that the 3D point coordinates in space can be obtained by combining the image matching results, thereby achieving the purpose of 3D reconstruction.

(3) Feature extraction: Features mainly include feature points, feature lines and regions. In most cases, feature points are used as matching primitives, and the form in which feature points are extracted is closely related to the matching strategy used. Therefore, it is necessary to determine which matching method to use when extracting feature points.

Feature point extraction algorithms can be summarized as three methods based on directional derivatives, methods based on contrast relationships of image brightness, and methods based on mathematical morphology.

(4) Stereo matching: Stereo matching refers to establishing a correspondence relationship between image pairs according to the extracted features, that is, one-to-one correspondence between imaging points of the same physical space point in two different images. When performing matching, pay attention to the interference of some factors in the scene, such as lighting conditions, noise interference, scene geometry distortion, surface physical characteristics, and camera characteristics.

(5) Three-dimensional reconstruction: With more accurate matching results, combined with the internal and external parameters of the camera calibration, three-dimensional scene information can be restored. Because the accuracy of 3D reconstruction is affected by factors such as matching accuracy, camera internal and external parameter errors, etc., the first few steps need to be done first, so that the accuracy of each link is high and the error is small, so that a more accurate stereo vision can be designed. system.