Wednesday, 21 April, 2021 UTC
Summary
Texture maps are essential to make your 3D images look real. They are applied to 3D models to create special effects, patterns or repeating textures. There are many different types of texture maps, but they all fall within two categories; PBR or Non-PBR.
PBR stands for Physically-Based Rendering and renders an image the same way it would look in the real world with physics based lighting. PBR is used in real-time applications like Unity and Unreal game-engines as well as the web. This is fast becoming the standard as many fashion brands realize the benefit of 3D on the web.
3D eCommerce has proven to double online conversion rates while using 3D in B2B sales has allowed brands to lower their carbon footprint, increase speed to market and reduce costs by replacing physical samples with 3D models.
https://medium.com/media/c64b44dee98fdcbad261a2fc7f71e45f/hrefThe most friendly real-time PBR file format is glTF or GLB and is supported by The Khronos group, a non-profit consortium of companies from HP, Apple, Adobe, Facebook, and more. glTF has a very well defined specification and can be used in game-engines as well as the web.
Non-PBR materials can give you very photorealistic results as they have many different settings to play with. This however, makes them much more complicated to learn. You also can not use these on the web, VR or AR so we will focus on PBR.
We’ll look at the following PBR maps which are most applicable to fashion:
- Albedo
- Normal
- Roughness
- Metalness
- Height
- Opacity
- Ambient occlusion
- Refraction
Albedo
The Albedo map is the base color input that defines the diffuse color or reflectivity of the surface. This is very similar to a diffuse map but is more the pure color of an object, while diffuse is both color as well as shaded with some diffuse lighting.
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Normal Map (aka Bump Map)
Normal maps give your object texture and depth by changing the direction light is reflected off your 3D model. These are also known as Bump Maps because they make your surface look bumpy. Normal maps don’t actually change the geometry of your 3D model so you can’t use them for extreme depth, but they are great to give realistic textures while keeping the polygon count low. Below is an example:
The left is a cube with a color texture while the right is the same cube with a normal map that gives it the brick texture. Normal map looks like the below when separated out from your 3D model:
Roughness Map
The Roughness Map (or Gloss Map) defines how light scatters across the surface of your 3D model. A 0 for Roughness results in a very shiny surface like plastic while a 1 is a more matte look.
Metalness or Metallic Map
Metalness maps are fairly self explanatory. They define whether the material is made of metal or not and work on a 0 to one scale. In fashion, metalness maps are most often used for trims.
Below are examples of these three maps and how they compare to each other:
Height/Displacement Map
Height maps are similar to Normal maps except they actually alter the geometry of an object. They are used to show more detailed elements of a material, but are usually only used in high-end game engines like Unity or Unreal or when being rendered within a program. 3D on the web currently doesn’t support them so it’s best to bake them in when exporting a 3D model that will be used on the web.
Opacity Maps
Opacity maps allow you to make certain areas of your texture transparent. If you wanted to create an effect like that you would see on a leaf, you can use an opacity map to make some areas transparent and some opaque. White is fully opaque and black is fully transparent.
Source: https://mimari3d.blogspot.com/2014/12/how-to-use-opacity-maps-in-3ds-max.html?spref=pi
Ambient Occlusion
Ambient occlusion (AO) is a map that the PBR engine combines with the albedo at render time to define how it reacts to light. A simple way to think about it is that instead of a very harsh shadow being cast, AO creates softer & more realistic global shadows around the edges of objects.
Rather than remaining black, shadows dissipate into halftones and obscure places that get less light.
Refraction
Refraction is the term used to describe the change in direction of a light wave due to a change in its transmission medium. In other words, when light comes in contact with certain surfaces, like water or glass, the light will get slightly bent because those surfaces affect the speed at which light travels through them. Refraction maps are a constant value that account for the amount of refraction in materials like water, plastics, etc.
Why Learning About Textures Maps is Important
One of the reasons it’s important for fashion designers to learn about texture maps is that it can help them diagnose issues when exporting from design programs. Browzwear and Clo are the two most popular apparel design softwares, both of which export glTF however sometimes the model you export doesn’t look the same as what you’re seeing in your design program. This is often due to an issue with one of your maps.
For instance, assets exported from Clo can often appear shiny, this is because Clo does not properly export the intensity value defined for the roughness property of your material. The way to fix this is to use a roughness map rather than an intensity value as this will ensure that any web viewer or game-engine will understand exactly how to render the roughness property.
Keyshot is another popular 3D design tool used for footwear and apparel. This program can utilizes proprietary materials to get photorealistic renders. While it has “PBR” settings, these materials are meant for progressive rendering and not realtime. Therefore, the materials you export do not always match what you see in the renders. Having an understanding of texture maps and their purpose can help you to understand what you may need to tweak to get the models looking correct up export.
Finally, many programs take advantage of V-Ray materials. V-ray materials are great for rendering images and videos, but cannot be used for real-time rendering. You’ll often see them used for materials like fur or fleece. The process of converting these materials can be pretty complex but VNTANA has helped automate this conversion process so you can save time and headache.
In order for 3D designers to take their designs to the next level they need to have a good understanding of textures, what they mean, and how they can improve the look of their garments. VNTANA can help 3D design teams improve and automate their processes and use their assets in eCommerce, b2b showrooms, and game-engines.
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https://medium.com/media/1e1f2ee7654748bb938735cbca6f0fd3/hrefWhat Are Texture Maps And Why Do They Matter For 3D Fashion? was originally published in AR/VR Journey: Augmented & Virtual Reality Magazine on Medium, where people are continuing the conversation by highlighting and responding to this story.