What is Rendering?

Graphical designing is a popular sector that focuses on creating realistic images. Rendering is the process of creating the final outlook of an image to create a design.

3D Graphic designing

Creating three-dimensional visuals with the help of software applications is known as 3D graphic designing. Graphic designers are the professionals that are trained to create digital images. The whole process of graphic designing to create three-dimensional images can be classified into three steps.

Modeling

Creating the shape and outline of the image is known as modeling. Various applications are available to scan real-life objects and directly create their outline. The designer can select the type of material for the objects. The base color and structure can be finalized in the modeling stage.

Layout

Creating a background and defining the movement of the object is categorized as layout and animation. It proceeds after the modeling stage. The layout defines the spatial arrangement of elements in the free space. Animation defines the movement of an image with respect to the surrounding. It is also known as the pre-rendering process.

Types of Rendering

The final stage to create a real-life-looking image is the rendering process. The 3D model is converted into an image by the process of rendering. To render a model, two different methods are used by the designers: photorealistic and non-photorealistic rendering. Rendering can be done on 2D and 3D models. Hyper-realistic rendering is the rendering style that involves both photorealism and non-photorealism.

Photorealistic rendering

Photorealistic rendering is also known as physically based rendering. To render an image, the designer will follow the flow and light. This type of rendering will create photorealism. Photorealism is the process of creating life-like-looking images based on a real-life object. The flow of light is determined by a series of rendering equations and functions. The software will provide a virtual sun, the position of the sun with respect to the elements is governed by the rendering equations. The equation is dependent on the luminosity and the reflective property of the object. Function renders, and the image is called bidirectional reflectance distribution function. BRDF is based on the reflectivity of the surface. It returns the radiance ratio of the element and helps to determine the direction of incoming and reflected rays of light. Unit of BRDF is the inverse of steradians.

The optical property of the material is finalized using photogrammetry.

In PBR, the designer can alter the surfaces and render the volume. The softwares available for PBR rendering are WEbots, Blender, MicroStation, and Babylon.js.

Non-photorealistic rendering

All expressive arts that range far from reality are created using non-photorealistic rendering(NPR). It focuses on creating art and logos that are based on animated cartoons. The main area of application of NPR is on videogames and cartoons. It is mainly used to render two-dimensional models to add a texture and effect. It focuses on artistic rendering. Here, shading and direction of light are not used to render the image.

Real time rendering

When rendering is happening in real time, the process is called real-time rendering. The three main stages of real-time rendering are application, geometry, and rasterizing. It is mainly used in video games and animated movies. It creates interactive images that are moving in real-time with respect to the 3D environment. It is time consuming and expensive process that can create on spot rendered images. Some software available for real time rendering are CAD, VRay, Indigo, and Rhino. AK peters have written Fundamentals of computer graphics, giving a detailed account of real-time rendering.

Rendering a 3D model

Render is the image that is created after rendering. The process of rendering an image involves texture, lighting, viewpoint, and shading. A graphic processing unit (GPU) is the part of the CPU that handles the rendering software. After creating a wire or mesh model, the rendering process is carried out. Bitmap textures are added to the model to complete the images. For rendering videos, each frame needs to be rendered individually. They are stacked together to create the completed video.

Features of rendering a 3D model

Rendering a model involves various features. Adjusting the brightness and color of the model is called adjusting shading. If the pre-rendered model is a curved surface, shading can add a lot of character to the element. Texture mapping and bump mapping involve texturing the model. Bump mapping can determine the bumpiness of the surface. The surrounding opacity is adjusted using fogging and participating medium. Shadows and soft shadows adjust the shadow of the element. Illumination, caustics, and diffraction handle the path of light. The transparency of the element is determined by transparency and translucency. The motion of the object is depicted by the motion blur feature.

Techniques used in the rendering of the 3D models

Rasterization, ray casting, and ray-tracing techniques are used in the rendering the 3D models. The best techniques collectively trace the light in the scene and help the designer to adjust every single ray that is falling on the element.

Rasterization

By rasterization, the vector image that is defined by geometric equations is converted to a raster image that is defined by pixels. This image will be stored in the bitmap file and is used in drawing 3D models or 2D primitive models. It involves mapping of scene geometry to pixels and it does not use any specific technique for computing the color of the pixels. Shading determines the color of each pixel. Rasterization is the conversion of a 3D model to adapt to the two-dimensional plane of a computer.

Casting

The view of the object from a particular direction can be designed using ray casting. Geometric algorithms are used to create the image from an observer's point of view. The adjustments can be made to the radiance and the shadows of the element. The position of the camera can be changed in ray casting and the image can be rendered from a particular direction. The direction of the ray is governed by the vector equations. Ray casting is mainly used to make line drawings, to make pictures that are shaded, and to calculate the physical properties such as the volume of an element.

Ray tracing

Ray tracing is the advanced method made by updating ray casting. Both ray casting and ray tracing use Monte Carlo techniques. The computation algorithms that are based on the randomness of taking the sample to create a result are known as the Monte Carlo technique. Ray tracing is capable of creating optical effects such as scattering reflection and dispersion. In this technique, the light is sampled to create an algorithm and this algorithm is used to render the image. This technique is used in photorealistic rendering. It focuses on the view of the element from the eyepoint and the properties of light falling on the object from this direction can be changed to create a realistic image.

Ray tracing is a time-consuming method and it was hard to combine it in real-time operations. Rendering images alone with ray tracing will not guarantee photo realistic images.

Each scene in ray tracing technology is mathematically described by the use of an algorithm and equations. The property of the light that is incident on the object is calculated using this algorithm and each property can be adjusted to make it look realistic.

Applications and software available for rendering

A wide range of applications and software are available for rendering. In laptops and desktop systems, Z-buffer is used to support computer graphics. Blender, Auto desk, Adobe are some popular design software. Rendering is a crucial step in 3D designing. It determines the outlook of the design.

Context and Application

Rendering is taught in various courses like-

• Bachelors in Computer Science.
• Bachelors in Graphic Designing.
• Bachelors in Animation.
• Masters in Graphic Designing.
• Masters in Animation.
• Bachelors in Architecture.

Practice Problems

1. Which of the following is not a process of 3D graphic designing?

1. Modeling
2. Editing
3. Layout
4. Rendering

Answer: b

Explanation- Editing is not a process of three-dimensional designing.

2. How many vectors are involved in designing a single ray element?

1. 1
2. 2
3. 3
4. 4

Answer: c

Explanation- 3D graphics deal with three-position vectors that depict the different coordinates. 

3. What feature is modified using bump mapping?

1. Bumpiness of the surface
2. The opacity of the surface
3. Empty spaces on the surface
4. All of these

Answer: a

Explanation- The bump factor alters the bumpiness of the surface. It can add texture and character to a surface.

4. What is the full form of GPU?

1. Graph Producing Unit
2. Graphical Prospecting Unit
3. Graphical Plotting Unit
4. Graphics Processing Unit

Answer: d

Explanation- GPU stands for Graphics Processing Unit.

5. Which of the following is the fastest method?

1. Ray tracing
2. Real-time rendering
3. Ray casting
4. Rasterization

Answer: d

Explanation- Rasterization is the fastest method to render a 3D model because it involves mapping of scene geometry to pixels and it is not based on any specific technique for computing the color of the pixels. 

Common Mistakes

Each process of rendering is governed by an equation. Therefore, calculation mistakes can cause unwanted changes in the process. Entering a wrong value in the reflection property of the material will affect the outlook of the image. Perspective can be a breaking or making point for every design. Choosing the wrong perspective can create distasteful effects on the final image.

Three-dimensional graphic design covers a lot of applications and involves a large scope of artistic development. Therefore overdoing a design is a very major mistake made by amateur designers.

Related topics

• 2D graphics
• Modeling
• Graphics pipeline