About 3d graphics
The basics of 3d modelling
3D Modeling
In three-dimensional computer graphics, 3D modeling is the process of mathematically representing any three-dimensional object. The final result is called a 3D model, which can be used as a two-dimensional image through a process called rendering or to simulate physical phenomena. Additionally, the model can be physically created using the appropriate 3D printing technology.
3D models can be automatically generated or manually crafted. The process of manually creating geometric data, known as modeling, is in practice very similar to sculpting or creating spatial plastic artworks.
Models
Representing 3D models as objects involves a collection of points connected by various geometric elements, such as triangles, line segments, and curved surfaces. As a set of points and other data, an object can be created manually, algorithmically, or through scanning.
3D models were widely used in 3D graphics long before personal computers became capable of rendering them in real-time. Many older computer games used pre-rendered images of 3D models before hardware could process them in real-time.
Today, 3D models are utilized in numerous fields:
- Medicine uses them for detailed representations of organs.
- The film industry relies on them for animated movies, generating both characters and objects through 3D modeling.
- The video game industry implements them in console and PC games.
- Scientific research uses them to visualize complex molecular structures.
- The construction industry employs them for architectural designs and visualizations, replacing traditional drawings and physical models.
- Engineers use them to design new tools and machinery.
The widespread application of 3D models continues to grow, revolutionizing various industries by providing precise, adaptable, and efficient digital representations.
Modelling the Yamaha XTZ 750
Modelling the Yamaha XTZ 750 2.
The 3D Modeling Process
There are four popular methods for representing 3D models:
- Polygon Modeling
In polygon modeling, points in 3D space, known as vertices, are connected by edges to form polygonal meshes. Software like 3ds Max utilizes this method. Today, most 3D models are textured polygon models because they are highly flexible and efficient to render. Although polygons are inherently flat, they can approximate curved surfaces by using a high number of small faces.
- NURBS Modeling
NURBS (Non-Uniform Rational B-Splines) use weighted control points that influence spline-based curves and surfaces. These curves follow, but do not necessarily touch, the control points. Unlike polygons, NURBS surfaces are inherently smooth, making them ideal for organic modeling. Maya is one of the most well-known commercial software applications that natively supports NURBS modeling.
- Spline & Patch Modeling
Similar to NURBS, this method also uses curves to define shapes. It provides a balance between polygon modeling and NURBS modeling, offering a compromise between ease of use and flexibility.
- Primitive-Based Modeling
This method builds complex shapes from basic geometric primitives such as spheres, cylinders, cones, and cubes. It is fast and easy to use, with mathematically precise dimensions and a simple descriptive language. It is best suited for technical modeling but is less effective for organic forms. Some 3D software can render primitives directly (e.g., POV-Ray), while others use them as editing tools, converting them into polygonal meshes for further processing.
Scene Layout
The scene layout involves arranging virtual objects, lights, cameras, and other elements within a digital environment. These components form the foundation for creating still images or animations.
Lighting and Atmosphere
Lighting plays a crucial role in this process. Just like in real-world scenes, light sources affect the aesthetics and realism of the final render. Achieving perfect lighting can be challenging, but it significantly influences the mood and emotional impact of a scene—something well understood by photographers and theatrical lighting designers.
Coloring and Texturing
Before rendering, it is often desirable to assign colors to a model’s surface. Most 3D modeling applications allow users to apply vertex colors, which remain visible in the final render. However, models are frequently textured as well.
A texture is a standard digital image mapped onto a 3D object. During the texturing process, additional UV coordinate data is assigned to the model, defining how the image wraps around the surface. Texturing enhances detail and realism, making objects appear far more intricate than they actually are.
Additional Effects
Beyond texturing and lighting, various rendering effects can be applied to increase realism. Examples include:
- Normal modifications that adjust surface lighting,
- Bump maps to create the illusion of depth,
- Other rendering tricks used to enhance visual fidelity.
Animation and Rigging
Many 3D models are designed for animation. Some animations are created directly within modeling software, while others involve exporting the model to specialized animation programs.
A common technique for animation is keyframing, which simplifies complex motions. The user sets specific time points (keyframes), and the program interpolates the transitions between them.
For organic characters like animals or humans, models are often rigged with bones and joints, allowing more natural movement. This process, known as rigging, significantly improves the realism of animated motion.
