Shading and Texturing
Shade and Texture is what illustrates what the object is made of according to its appearance. Shading dictates how light bounces off a surface, and texturing can add details such as bumps and crevices to a surface. Some software may have a library of materials, but it is not difficult to create textures using procedural methods and/or images. Blender, for example, does not come with a library of materials, but provides the versatility to create any texture. Below are a few aspects that you need to consider when creating an accurate texture. If you are going for the realistic look, texturing is what you will need to master.
If you are interested in a quick overview on how to create a node-group that can simulate a large variety of realistic materials, refer to BlenderGuru's PBR (Physically Based Rendering) textures.
Decreasing the roughness of an objects makes it look smooth. Rough surfaces diffuse the light and prevent light rays from direct reflections. If you have a metallic material, having a low roughness will make it more reflective.
Also known as bump map, is a method of displacing the surface to simulates the details of a model. The image is usually black and white, where the value of each pixel dictate how much height to add to the surface, with 50% grey having no effect on the surface. Bump maps are good at adding details that does not require, or cannot be achieved through modelling, such as crevices on a brick wall, scratches on a metal surface, or the grain in a wooden floor.
Normal maps are another way to displace the surface of an image and it is similar to height maps, but instead of having height information, they contain angle information. They are colorful because each color records which way the face is pointing. An example is shown blow.
Example of a Normal map
Without Displacement mapping
Example application of a Normal map
With Displacement mapping
No surface is perfect in the real world and adding surface imperfections can add significant realism to a render. All though for a basic project demo this may not be necessary and you might be even shooting for a perfect looking product. However, I found, that even if you are going for a flawless product look, having that product in a realistic world, will make your animation or render look very compelling. Thus, adding surface Imperfections to background objects, such as floors, tables and walls can make your product standout. Even in Disney movies, use PBR materials even though the characters are heavily stylized.
Below is an example on how adding fingerprints to a glass can add a lot more realism into a scene. The texture used here is from Poliigon.
Without Displacement mapping
Simple method for applying fingerprints
How to Make Photorealistic PBR Materials (https://www.youtube.com/watch?v=V3wghbZ-Vh4&t=999s)
Poliigon Textures (https://www.poliigon.com/)