This is a short article about the basic workflow of making a 3D model on a computer. I only started learning digital 3D art skills last year, so I’m writing this for beginners. When started learning 3D art I often felt frustrated. 3D art is very technical and the more you learn the more you find there is to learn. It can be a rabbit hole. This article is not going to go into too much detail, I’ll keep it as simple as I can. I’ll also list some resources at the end of this article which I have found useful.
The basic workflow for creating 3D models is as follows:
- Idea and concept design stage
- 3D modelling and Sculpting
- UV Mapping
- Texture Map Baking
- Texturing and Painting
Idea and concept design stage
This stage is where you decide what you want to create in 3D. Designers create orthographic drawings so that the 3D artists will have good reference for creating a 3D model.
3D modelling and Sculpting
The 3D modeller will take the orthographic designs and other relevant drawings and create a 3D model using them for reference. Different modelling techniques are used depending on the technical requirements.
For more organic designs and detailed characters 3D sculpting is used. For hard surface or low-poly style models 3D modelling techniques are used. This is not always the case nowadays with changes in technology. Hard surface modelling can be created using sculpting techniques as well in some programs or with special add-ons.
If the 3D model requires a lot of detail, say for an AAA computer game or animated film, this will be made into a high resolution mesh object. When creating your 3D model with modelling techniques it is useful to know about good topology. Sculpting is considered a more intuitive and artistic way of creating a 3D model but it is still useful to know about topology for the next process.
Retopology is the process of making a simplified base mesh from a high resolution sculpted mesh that can then be used for animation and texturing. If you are creating 3D models for art reference or still images you may get away with avoiding this step.
There are lots of manual methods for doing retopology. There are automatic retopology methods available which can be useful for models like rocks or trees which won’t be under as much scrutiny as characters or in the distance. The reason retopology is useful for texturing is that it makes the process of UV Mapping easier.
If you will be using image textures for your 3D model you first need to unwrap the model. Image textures are 2D objects so they always need UV mapping to be applied to the objects surface. UV mapping is like wrapping a 3D object with paper, first you have to unfold the object flat to place the image texture on to the surface. It is also a bit like creating a sewing pattern backwards. Indeed some people use 3D models to create sewing patterns and paper craft patterns in this way. You mark seams on the 3D model and flatten areas of it out into a 2D representation which will be used for the texturing and painting process.
If you are using procedural textures you can usually get away with not unwrapping your model. Procedural textures can be generated in 3D space so they don’t usually need UV mapping.
There are manual methods for UV mapping and automatic methods. Automatic methods are useful for quickly unwrapping objects like background environmental things that won’t be under as much scrutiny as characters. Automatic methods can be very useful to a 3D artists workflow, yet It is useful to learn manual unwrapping methods as well because it makes the painting process easier.
Recently more specialized software is being developed to aid in the unwrapping process such as Ministry of Flat. I was impressed with the results, but I appreciate knowing the manual process because sometimes you have to tweak the automatic results.
Texture Map Baking
Map baking involves transferring the light information, the material information and the geometry information of a high resolution 3D mesh object into image texture maps. The most common maps generated for this use are normal maps, specular maps, ambient occlusion maps and cavity maps. Ambient occlusion and cavity maps can be useful in the next process of texturing the 3D model. They show the inner edges of the model where occlusion shadows are, making it easier to define areas for painting.
The resulting image texture (s) can be used on a lower resolution mesh object to make it appear as the high resolution mesh object with far less geometry to load. It is useful for exporting the rendered result of a 3D mesh into an image texture so that it will look as intended in a different graphics engine. For example many effects (materials) can be created using Blender’s render engines with “nodes”, but these materials will not be transferred with the 3D mesh unless they are “baked” into an image texture and saved first.
Texturing and Painting
For 3D models textures are often created to give them more realistic or stylized looks depending on the art direction. The most common texture workflow these days is PBR (physically based rendering) but older methods are also used sometimes if a more stylized look is desired. NPR (Non-photo realistic rendering) is also popular for creating more artistic styles such as cell shading. The hand painted style is very popular as well.
Textures are also very useful for creating the illusion of high detailed objects when the 3D mesh is very basic. Realistic looking foliage for example can be created with transparent textures that are mapped onto a low-poly mesh.
You need to create an image texture first to start texturing a 3D model. Textures use power of 2 numbers such as 16, 32, 64, 128, 256, 512, 1024, 2048. For models that need to be seen close up with lots of detail the higher resolutions are used.
There are different types of textures you can create.
Tiling or seamless textures are the default behavior for most 3D software. They can be useful for landscapes and filling large areas with texture. These can be generated from existing images or hand painted. Knowledge of creating seamless patterns is useful.
Trim textures are horizontal or vertical strips of tiling patterns. Geometric border patterns are useful as well. Trim textures use different strip widths on one image, on one theme such as stone tiles to a coherent theme. Small bands of varying texture and patterns are useful to create variation. Trim textures are good for large architectural and structural objects and background objects such as pots. This is also known as a texture atlas. This technique is used quite often in 3D games because it helps optimize the render times.
UV Unwrapped Textures are created for more complicated 3D models such as characters and anything that needs hand painting or texturing. 2048px by 2048px is common for creating 4 k res textures. 512px by 512px to 1024px by 1024px is a good guideline for game assets.
For more on texturing workflow in particular I wrote this article.
Put very simply, rendering is the process of lighting your scene and placing your camera to create a final “rendered” image. Blender has its own rendering engine called Cycles but there are lots of different rendering engines in different software.
I found these useful.
(CG Cookie offers a free Blender curriculum lesson plan for art educators which may serve as a good guide to the learning process. I’ve used CG Cookie and I can definitely recommend them.
There are lots of good courses for learning the technical ins and outs of creating 3D models on Udemy.