What Are the Different Types of Skeletal System Models?

A 3D model is a polygonal representation of an object, usually displayed using a computer or other video equipment. The displayed objects can be real-world entities or fictional objects. Anything that exists in physical nature can be represented by a three-dimensional model.

3D model

3D models are often generated using specialized software such as 3D modeling tools, but can also be generated using other methods. As data of points and other information sets, the 3D model can be generated manually or according to a certain algorithm. Although it usually exists on the computer in a virtual way or

At present, there are generally three methods for modeling objects: the first method uses three-dimensional software to model; the second method uses instrumentation to measure and model; and the third method uses images or videos to model.

3D software modeling

Artificial modeling

At present, many excellent modeling software can be seen in the market, the more well-known ones are 3DMAX,

SoftImage, Maya, UG and AutoCAD, etc. Their common feature is the use of some basic geometric elements, such as cubes, spheres, etc., to construct complex geometric scenes through a series of geometric operations, such as translation, rotation, stretching, and Boolean operations. The use of modeling to build three-dimensional models mainly includes geometric modeling (Kinematic Modeling), behavior modeling (Kinematic Modeling), physical modeling (Physical Modeling), object behavior modeling (Object Behavior), and model segmentation (Model Segmentation). Among them, the creation and description of geometric modeling is the focus of virtual scene modeling.

Modeling with instruments

The 3 Dimensional Scanner is also called a 3 Dimensional Digitizer. It is one of the important tools currently used for 3D modeling of real objects. It can quickly and conveniently convert real-world stereo color information into digital signals that can be processed directly by a computer, providing an effective means for digitizing physical objects. It is very different from traditional flat scanners, cameras, and graphic capture cards: First, its scanning object is not a flat pattern, but a three-dimensional object. Secondly, by scanning, three-dimensional spatial coordinates of each sampling point on the surface of the object can be obtained, and color scanning can also obtain the color of each sampling point. Some scanning devices can even get structural data inside the object. The camera can only capture one side of the object, and it will lose a lot of depth information. Finally, it does not output a two-dimensional image, but a digital model file containing the three-dimensional spatial coordinates and color of each sampling point on the surface of the object. This can be used directly for CAD or 3D animation. Color scanners can also output color texture maps of object surfaces. An early coordinate measuring machine (CMM) was used for 3D measurement. It mounts a probe on a three-degree-of-freedom (or more-degree-of-freedom) servo device and drives the probe to move in three directions. When the probe contacts the surface of the object, the three-dimensional coordinates of the surface of the object can be known by measuring its movement in three directions. Controlling the probe to move and touch on the surface of the object can complete the three-dimensional measurement of the entire surface. Its advantages are high measurement accuracy; its disadvantages are high price, complicated control when the shape of the object is complex, slow speed, and no color information. Relying on the principle of radar, people have developed laser or ultrasonic media instead of probes for depth measurement. The rangefinder sends a signal to the surface of the measured object. Based on the signal's reflection time or phase change, it can estimate the spatial position of the surface of the object, which is called "flying spot method" or "image radar".

Model from image or video

Image-Based Modeling and Rendering (IBMR) is the current computer graphics

Image-based modeling

An extremely active research area in the world. Compared with traditional geometry-based modeling and rendering, IBMR technology has many unique advantages. Image-based modeling and rendering technology provides us with the most natural way to obtain photorealism. Using IBMR technology, modeling becomes faster and more convenient, and you can obtain high rendering speed and high realism. . The latest research progress of IBMR has achieved many fruitful results, and it is possible to fundamentally change our understanding and concept of computer graphics. Since the image itself contains rich scene information, it is naturally easy to obtain a photo-realistic scene model from the image. The main purpose of image-based modeling is to restore the three-dimensional geometry of a scene from a two-dimensional image. The restoration of the three-dimensional shape of the scene from the two-dimensional image originally belonged to computer graphics and computer vision. Because of its broad application prospects, researchers in computer graphics and computer vision are now interested in this field. Compared with the traditional method of obtaining a stereoscopic model by using modeling software or a three-dimensional scanner, the image-based modeling method has low cost, strong sense of reality, and high degree of automation, and thus has a wide application prospect.