The Basic Building Blocks of 3D Objects

3D Models and 3D Materials

August 9, 2021 · 15 minutes read

This article is part of a series designed and written for marketing and sales professionals who would like to gain insight into the technical challenges of leaving behind the traditional way of marketing material creation by switching to the 3D approach. Computer graphics is a complex topic and the goal of this series is to give enough technical background to allow for appropriate business decisions, while also not overwhelming the reader with unnecessary details or mathematical equations.

The Split

When you take a photograph of your product, you require a physical version of it. Moving the photography process to the virtual realm replaces this requirement with the digital version of your product. Unless you have a background in 3D or experience with CAD (computer-aided design) software, you might find the following technicalities somewhat peculiar at first.

In 3D, every item consists of two building blocks: the form and the finish. If you look at the above radio and its wooden case, you could argue that it was made from a single piece of wood using a mold and a woodworking technique called steam bending. The form and the finish are one and the same. In 3D, however, these two are very different pieces of data. They are different in how they are created, stored, and used. The form of a product is called a 3D model while the finish is called a 3D material. These two are actually so different that even the people who are working on one or another belong to different company departments: modeling and shading. Someone could become proficient in both, but you can easily spend multiple years, or even decades, learning only one.

So, in 3D, we have the two building blocks - the model and the material - for creating the digital version of your product.

The 3D Model

The 3D model is a piece of data which describes the shape of an object. Sometimes referred to as geometry or CAD as well. If we were to take the radio and remove all the 3D materials, we would have an image of the 3D model:

This is also called a clay render. It is often used to showcase the work of a 3D modelling artist. It might not look too attractive to a technically untrained eye, however, experienced modelers not only love looking at images like this, but they also use them to demonstrate their skills or judge that of others. To be technically correct, this 3D model is not without any materials. It has a simple, clay-looking material applied to every part of it, which is the standard practice for visualization purposes.

There is a vast range of techniques how a 3D model can be created: sculpting, subdivision modeling, boolean operations, splines, NURBS, displacement, photogrammetry, particles, kitbashing, 3D-scanning, CAD modeling, cloth and fluid simulation, parametric modeling, generative modeling, fractals, or even artificial intelligence. More often than not, multiple methods are used to create a single model depending on its complexity. If you would like to have a visual impression of what some of these technical terms mean, watch the following video by Gleb Alexandrov:

It is important to mention that not all 3D models are alike nor appropriate for the creation of highly realistic images or configurators. We at colormass almost never receive 3D models from our customers which can be used directly without either re-creating them from scratch or improving them to a level matching our quality requirements. A specific example would be the CAD files of office furniture. Although these can be very helpful, especially regarding the mechanical parts of a furniture piece, upholstered parts like the seat or the backrest of a chair seldomly ever contain all the details necessary, like the stitching or some subtle wrinkles. Not adding these extras can quickly lead to unsatisfactory results.

To create high-quality, precise 3D models of your products, we ask for reference photos from multiple angles. These do not have to be professional images, they can even be taken by a smartphone in the factory. The more, the better, so we can see all the intricate details of the product. If there are technical drawings or CAD files, we are happy to incorporate those into our modeling pipeline. Depending on the type of product offered, they can speed up the process.

The 3D Material

The 3D materials are pieces of data which describe the finish of an object. It is often referred to as shader. The process of creating 3D materials is called shading and somebody who is doing this professionally is a shading artist. This is where the object below got its name from, a shader ball:

A shader ball is an arbitrary shape, normally having some curved surfaces, which is often used to represent a material. The rounded sides help provide a feel for the properties of a particular finish, including color, glossiness, and roughness. The pencil on the right is included for a frame of reference of the real-world size of the finish.

Since models can be thought of as three-dimensional drawings, they are simpler  to conceptualize. In contrast, 3D materials are not something you can relate to without learning a completely new abstraction. In everyday terms, a 3D material is the data which describes how a specific kind of surface reacts to light. Given that even if you only focus on the visual aspects, the interaction between light and matter is very complex, computer graphics uses simplified models to simulate real-world phenomena.

If someone was to ask you to describe the material of a regular object surrounding you like a table, a pen, or an eraser, you probably would start by telling them about its color. Although it is a good starting point, there is much more to a material than that. An additional property to mention would be the shine or how rough it feels to the touch. A plastic pen is shinier than an eraser. What about the chrome legs of the table? It is a metallic surface, which again, is visually quite different from both the plastic pen and eraser made of rubber, given its reflective properties.

How these materials are created in 3D is very similar to how audio mixers work. Different properties such as roughness, metalness, specularity, sheen etc. can be mixed and matched to achieve the desired look of a material. The image above is showing these parameters and how increasing their strength from left to right changes the visual appearance, here shown through spheres. If you are interested in understanding more details about these parameters, read through the Blender documentation of the Principled BSDF node or watch the following video:

One way to create a material is to start from scratch and tweak the above parameters till the desired look is achieved. This works well for homogenous materials like glass, gold, or a solid colored surface. However, most real-world materials are much more intricate and have elaborate details which cannot be easily reproduced without so-called textures or maps. Imagine an oak cabinet. In order to convey the feel of a realistic surface, the grain plays a critical role. The easiest way to produce a wooden grain is to photograph a flat piece of oak and use it as a texture, which is nothing more than a digital image. So, instead of picking a solid color for the diffuse parameter, a photo of the oak would be used. The other parameters could be tweaked manually, e.g. the roughness, to achieve a lacquered look.

Although this sounds quite straightforward, simply photographing real-world materials and using them as a diffuse texture is not going to result in a highly realistic outcome. For example, fabrics are exceptionally complex regarding their reaction to light. Hence, colormass developed an in-house scanning solution in order to capture not only the diffuse map but also many others. This makes it possible to digitize fabrics true to their nature in an automated process. The results are so-called PBR assets, which fabric manufacturers can provide to space planners, interior designers, and architects for visualization purposes.

Combining the Two Blocks

Once the 3D model and the 3D materials are created, they can easily be combined. A material can be assigned to every part of the model in a “drag and drop” fashion. There are no limitations regarding which pieces get which finish, which offers extreme flexibility in creating  any product variation. This is one of the core advantages of 3D, especially if your products are highly customizable. Together with your digital data and the colormass approach, every admirable detail of products are captured in their full glory.

This article gave a short overview of the basic building blocks of 3D: the models and the materials. People often are familiar with the concept of the former and have limited understanding of the latter. The reason for this is probably the fact that it is much easier to relate to the form of a product, which is essentially a 3D drawing, than to its surface properties, which involve the physics of matter and light interaction. However, it is important to stress that both of these components play an equally significant role when it comes to the creation of esthetically appealing visuals. For this reason, multiple separate articles are going to be dedicated to both models and materials.

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