The amount of physical parameters as well as the simulation engine inside the software determine the virtual material’s drape. While it is still difficult to test physical materials accurately to generate the right parameters¹, also each cloth simulation engine’s interpretation of these values varies. Generally speaking it is important to have parameters for the most important factors, for example bend, stretch or shear. Consistency in the testing method is also important to have comparable outcomes amongst materials.
The visual representation of a material starts with a picture of the actual material. Here you have different ways and levels of quality which go from taking a simple picture, flatbed scanning or more advanced material scanning devices such as xTex or TAC.² Also for the visualisation of a material you have several parameters determining the quality and realism of a 3D garment. Next to the actual image or so called diffuse map which holds the color information of every pixel there are several more:
• specular map: contains the reflectivity information, hence determining how a material absorbs and reflects light.
• bump map: carries information about the material’s structure in form of shadow levels. While a relief effect can be achieved, the structure is only based on shadow levels and actually ‘an illusion’, hence no real geometry is created by this map.
• alpha map: holds information on a material’s transparency and translucency.
• roughness map: is responsible for the roughness respectively glossiness of a material.
• displacement map: contains the ‘real’ data about a material’s structure. When applying this map to a material you do get actual geometry.
¹ there are only a few options for physical testing currently. Some brands do it manually within defined testing methods, others create and adjust values ‘by look’. Browzwear introduced an automated fabric testing kit last year which reduces the manual work quite a bit whilst also eliminating the human error and enables consistency. However, there are tons of parameters which eventually define the physical behavior of a material. After all it comes down to what you can and want to measure as well as the amount of values the respective software reads and how it processes them.
² having a material scanning device is recommendable when you want to integrate 3D in your daily business and at a scaleable level. Depending on your business setup with regards to product, timelines as well as 3D goals, a simple flatbed scanner might be sufficient at first. When you start building up a library of virtual materials it does become a tedious task though. The amount of manual work that goes into tiling and additional map creation is time consuming and inconsistent, so that purchasing a material scanner with more capabilities becomes a very rewarding investment.