This article is for anyone who may need a 3D model made and wants to know about the 3D modeling process. It will explain who/how/where 3D models are used. This article also explains the process of creating 3D models and highlights the key steps that a project manager may need to be aware of. However, this is not a step by step guide on how to make a 3D model. There are so many other tutorials for this!
So what are 3D models used for? This is a very important question because it ultimately dictates how the 3D modeler will make the 3D models, and what software will create the rendering. Let’s have a look at the typical uses, users and the differences.
3D Product Animation and Visualisation:
3D models are required for product animation and visualisation projects. This can range from high end TV commercials to simple 3D product rotation. If the animation or visualisation is done in 3D, 3D models are almost always used. The users of these 3D models are likely to be 3D animators, 3D visualisers and 3D artists.
3D models used for animation and visualisation tend to be very artistic and therefore tends to be modeled using the artistic eye. Although realistic dimensions are often required, these models may be deliberately altered to maximise the artistic impact. The models need to be highly flexible because they often require rapid amendments from the art director. Because 3D animation and visualisation are very artistically orientated, the 3D models almost always require textures and shaders to make the rendering look beautiful and/or photorealistic. Special consideration is required if the 3D model is required to be animated. This will affect the 3D modeler workflow and output.
3D Design and Prototyping:
Computer Aided Design (CAD) is a very popular method for designing because it is so fast and versatile. It is the method of choice for today’s designers. 3D models are created to allow the designer to visualize the design before a real life prototype can be created. Once the 3D model is created, the designer can rapidly make changes to the design. These 3D models are often created and used by the designers.
3D models for design and prototyping tends to be a very engineering orientated discipline unlike animation and visualisation work. These models are very parametric i.e. the models are built using parameters as opposed to “by eye”. This allows for very accurate models that can be rapidly altered to reflect design changes. However, the models are also very rigid, as defined by their parametric set up. Deviation from this parametric set up will require the model to be restructured. These models are also very “heavy“ i.e. the file sizes are large and, due to the modeling style/format, the model’s mesh is very high in poly count. This is not an issue if the 3D model remains in its native modeling program. However, when exporting to other modeling software, issues often arise but can be resolved manually and with patience.
3D models for design work tend not to have textures and shaders as the designers are more interested in the shape and form of the design rather than beautiful renderings.
3D models are used extensively in real-time applications. Most common uses are in the games industry, web apps, mobile apps, Augmented Reality (AR), e-learning and Computer Based Training (CBT). The completed 3D models are handed to the real-time engine programmers. The programmers then link the 3D models to the user. This allows the user to control and manipulate the 3D model in real-time. The experience is much more interactive than with 3D animation which allows for no user interactivity.
3D models for real time applications are very different from the models required by animation/visualisation and 3D design work. Because of the real time environment to which these 3D models have to operate, these models are optimized to allow for extremely fast rendering (about 30-60 times a sec). As a result the 3D models are made to be as “light” weight as possible by keeping the polygon count low and the texture files small. Non-real-time environments such as 3D animation and visualisation do not have this rendering limitation.
3D printing and 3D sculpture
There are two more areas that require 3D modeling; 3D printing and 3D sculpturing but I will leave these for a separate article. Basically, 3D printing requires a specially prepared 3D model that is designed to be recreated (printed) in real life. No other 3D modeling techniques does this. 3D sculpturing is an extremely “heavy” modeling workflow but it allows for a very flexible, creative and organic workflow.
The 3D Modeling Workflow:
I have recently been asked to create a 3D model of a Stannah stair lift (a large manufacturing company based in Wiltshire) to be used in an Augmented Reality (AR) application for the ipad. There are many methods for creating 3D models but the method discussed in this article was the chosen method for the Stannah Augmented Reality project. The workflow is optimized for 3D animation and visualisation projects but has been adapted for a real-time workflow.
The typical 3D modeling workflow is as follows:
- Requirement- understand the project requirement and choose the best modeling technique and software to support the final file format.
- Collate reference material
- Prep reference material for 3D software
- Start 3D modeling
- Create textures and shaders/materials
- Setup and bake lighting
- Export to correct file format
There must be a clear understanding of the requirement for the 3D models before any work can begin. As discussed above, there are many different uses for 3D modeling which means the workflow must adapt to the type of use. Further adaptation must be implemented to allow for the final file format and its limitations. Understanding the final file format’s limitation beforehand will avoid unnecessary additional work and alteration later in the process.
Collate reference material:
This is a very important stage. Good collation of reference material will save a lot of time further down the workflow and will determine the quality of the modeling and the texturing. Good cameras and lighting equipment is also essential.
However, there are situations where the correct light setup cannot be achieved and full accessibility to the subject is restricted. These limitations are as expected in most projects. The ability to take photographs of the real object is a real advantage because it provides excellent reference material but can also be used for texturing (especially with real time applications). However, it can also be a hindrance depending on the quality of the light setup. Poor light setup will have unwanted artifacts on the photographs which then have to be removed at a later time.
Normally with photography, the aim is to capture the subject in:
- an interesting posture and composition,
- good lighting which helps to make the subject more three dimensional
- interesting lighting with many tones and texture.
However, the aim of taking photographs for 3D modeling is the opposite. The aim is to take:
- reference photographs that are as flat on to the subject as possible to minimize perspective and distortion. These flat images are used as references for modeling so they need to show the dimensions of the subject as accurately as possible.
- reference shots from as many different angles as possible to build up a library of images to use as guides. As a rule of thumb, the more complicated the subject, a larger variation of angle shots you will need.
- photographs of the subject in a “bad” light setup i.e. the lights needs to make the subject appear to be as flat as possible to minimize highlights, shadows and any other artifacts. These photographs may be used as textures for the 3D models. When brought into 3D software, these textures will have highlights and shadows applied to them. If they already contain highlights and shadows, the resultant rendering will have two lots of highlights and shadows in different places. This creates an image that is incorrect and very confusing for the human eye.
- photographs of different textures/material of the subject may be required. For example, if the subject is a chair, take different photographs (flat on) of the soft upholstery and wooden arms etc. Ideally, photographs of these textures/materials should also be taken in various lighting condition to allow for the study of light on the chosen material. This study will support the reproduction of the material in the 3D software.
Additional notes and other considerations:
- In an ideal workflow situation, the photographs should have no (or little) shadows, highlights or other artifacts. These photographs can then be used to texture the 3D models. Shadows, highlights and other artifacts are then generated within the 3D software.
- However, sometimes due to budget, it may be too time consuming to follow this workflow. Instead, it may be worth considering taking photographs with shadows, highlights and other artifacts on the subject. Again, these photographs can then be used to texture the 3D model but, this time, the 3D software is no longer required to reproduce these details. This is a quicker workflow but the resultant quality of the 3D model will be reduced. Control over the lighting of the 3D model is also dramatically reduced.
- If there are any moving parts on the subject, take photographic reference of how it moves and how it is attached to the subject. Take photographs before and after the movement. Pay particular attention to the details of the subject that is covered up by the moving object.
- If the subject has lots of remove-able parts (i.e components), make notes of their locations and how they attach/remove, and make an inventory of all the parts to be photographed individually.
- In addition to all the photographs, it is wise to collate as much information about the subject as possible such as blueprints, schematics/diagrams, drawings etc. As a rule of thumb, this procedure should always be followed. This is especially important if access to the real life subject is not possible!
Prep reference material for 3D software
Once all the necessary reference material has been collated, they will need to be prepped for 3D modeling. The reference material will need to be organized and edited into front/back view, side view and top/bottom views. These images are imported into a 3D modeling software to be used as guides. It is therefore extremely important to pick reference photographs that have the minimum amount of distortion or perspective. For this reason, it is often best to use schematic diagrams instead of photographs. If no schematic diagrams are available, any distortions in the photographs will need to be reduced using Photoshop (or similar).
Every reference image will then need to be scaled and aligned relative to each other.
Start 3D Modeling
The 3D modeler will then create a 3D mesh of the chosen subject using the reference images as guides. This will usually look like a grey 3D clay model.
Create textures and shaders/materials
Once the 3D model has been completed, texture and shaders may be applied. Textures usually come from photographs or are hand painted.
If photographs are used, it is important that the photographs have no shadows, highlights or other artifacts. However, in a real situation, this may be impossible. The next step is to then remove these details to produce a flat as possible image. This requires good Photoshopping skills. There are many tutorials on this subject so I will not cover them here.
The lighting setup will be dependent on the rendering technique of the project. If the 3D model is intended to be used in 3D animation or visualisation, it will likely be used in a non-real time rendering environment. This means lighting may not be required by the modeler because the animator, visualizer or even the lighting artist will want to control the lighting. If this is the case, the 3D model is completed.
If the 3D model is required for real time applications, lighting may be required to be “baked” onto the texture of the 3D model. This is because “baked” on lighting will remove/reduce the need for the real time 3D graphics engine to calculate lighting information. The result is less overhead for the computer/device so the application can run faster and smoother.
Export to correct file format
The completed 3D model and textures will need to be exported to the correct format for whatever the intended use will be. Depending on the limitation of the file format, the 3D model may require further alteration or reduction in order to work with the file format.
That is the overview of a typical workflow for a 3D modeling project. If you do require 3D models to be created, contact BeanBox or hire a 3d freelancer to do it. Make sure to hire a 3d modeler with experience in creating a wide variety of 3d models, 3d design, 3d graphics, texturing and 3d rendering. Click here for a further guide into the differences between the types of 3D freelancers.