8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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Elliminate Texture Confusion: Bump, Normal and Displacement Maps

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8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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Have you hit a bump on the road to mastering textures for your 3D assets? Don’t feel bad! Many

artists who are new to texturing or 3D (http://www.digitaltutors.com/subject/3d-texturing-tutorials) in

general experience confusion when encountering bump, normal and displacement maps for the first

time. They all seem to do sort of the same thing, right?

The answer to that question is a resounding “sort of.” Each one of these three types of maps creates

something that looks like additional resolution or detail on the surface of geometry. Some of this

detail is real and some isn’t. In this article we will dive into each of these three maps and learn what

each map does and what they don’t. You’ll also have a better grasp on the strengths and weaknesses

of each type of map.

Bump MapsA bump map is actually one of the older types of maps we’ll look at today. The first thing you should

understand about bump maps is that the detail they create is fake. That’s right, bump maps create

the illusion of depth on the surface of a model using a very simple lighting trick. No additional

resolution is added to the model as a result of a bump map.

Typically, bump maps are grayscale images that are limited to 8-bits of color information. That’s only

256 different colors of black, gray or white. These values in a bump map are used to tell the 3D

software basically two things. Up or down.

When values in a bump map are close to 50% gray, there’s little to no detail that comes through on

the surface. When values get brighter, working their way to white, details appear to pull out of the

surface. To contrast that, when values get darker and closer to black, they appear to be pushing into

8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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the surface.

Bump maps are really great for creating tiny details on a model. For example pores or wrinkles on

skin. They are also relatively easy to create in and edit in a 2D application like Photoshop considering

you are just using grayscale values.

The problem with bump maps is that they break pretty easily if the camera views them from the

wrong angle. Since the detail they create is fake and not real resolution being added, the silhouette of

the geometry that the bump map is applied to will always be unaffected by the map.

 

Normal MapsNormal maps can be referred to as a newer, better type of bump map. As with bump maps, the first

thing you need to understand about normal maps is that the detail they create is also fake. There’s no

additional resolution added to the geometry in your scene. In the end, a normal map does create the

illusion of depth detail on the surface of a model but it does it differently than a bump map.

As we already know, a bump map uses grayscale values to provide either up or down information. A

normal map uses RGB information that corresponds directly with the X, Y and Z axis in 3D space. This

RGB information tells the 3D application the exact direction of the surface normals are oriented in for

each and every polygon. The orientation of the surface normals, often just referred to as normals, tell

the 3D application how the polygon should be shaded.

In learning about normal maps, you should know that there are two totally different types. These two

types look completely different when viewed in 2D space.

8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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The most commonly used is called a Tangent Space normal map and is a mixture of primarily purples

and blues . These maps work best for meshes that have to deform during animation. Tangent Space

normal maps are great for things like characters. For assets that don’t need to deform, often times an

Object Space normal map is used. These maps have a rainbow assortment of different colors as well

as slightly improved performance over Tangent Space maps.

There are definitely some things you need to be aware of when considering using a normal map.

Unlike a bump map, these types of maps can be very difficult to create or edit in a 2D software like

Photoshop (http://www.digitaltutors.com/software/Photoshop-tutorials). Likely, you will bake a

normal map (http://blog.digitaltutors.com/tips-creating-perfect-normal-maps-every-time/) out using a

high resolution version of your mesh. There are however some exceptions for editing these types of

maps. MARI (http://www.digitaltutors.com/software/MARI-tutorials) for example has the ability to

paint the type of surface normal information we see in a normal map.

When it comes to support, normal maps are pretty well integrated into most pipelines. Unlike a bump

map, there are exceptions to this rule. One of those would be mobile game design. Only recently has

hardware evolved to the point where mobile games are beginning to adopt normal mapping into

their pipelines.

Displacement MapsWhen it comes to creating additional detail for your low-resolution meshes, displacement maps are

king. These types of maps physically displace (as the name implies) the mesh to which they are

applied. In order for detail to be created based on a displacement map, usually the mesh must be

8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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subdivided or tessellated so real geometry is created.

The great thing about displacement maps is that they can actually be either baked from a high

resolution model or painted by hand. Like a bump map, a displacement map consists of grayscale

values. Here is the real kicker though. While you can use an 8-bit displacement map, you will almost

always experience better results by using a 16- or 32-bit displacement map. While 8-bit files may look

good in 2D space, when brought into 3D they can sometimes cause banding or other artifacts as a

result of the insufficient range in value.

Now, here’s the not so great thing about displacement maps. Creating all that additional geometry in

real time is extremely difficult and hard on your system. Because of this, most 3D applications

calculate final displacement results at render time. In comparison to bump or normal maps, a

displacement map will also add significant time to your renders.

As a result of this additional geometry, it’s hard to beat the results of a displacement map. Since the

surface is actually modified, the silhouette reflects the additional geometry. You should always weight

the expense of a displacement map against the added benefit before deciding to use one.

Using These Maps TogetherIn some cases it may be possible for you to combine either a bump or normal map with a

displacement map on the same asset. The best way to do this would be to utilize displacement for the

big changes to the geometry and then the normal or bump for the fine detail.

8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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Regardless of which map you choose to use, understanding how each map works and both it’s

strengths as well as it’s weaknesses will only make your decision easier. Ultimately the map you go

with should be the one that best fits the needs of the scenario you find yourself dealing with. If you’re

interested in checking out training that deals with these three different types of maps, make sure and

check out the texturing courses you’ll find for ZBrush

(http://www.digitaltutors.com/11/training_search.php?searchString=texturing), Mudbox

(http://www.digitaltutors.com/11/training_search.php?searchString=texturing) and MARI

(http://www.digitaltutors.com/11/training_search.php?searchString=texturing).

Tags in this article

SUBJECTS

Fundamentals (http://blog.digitaltutors.com/subject/fundamentals/),

Game Art (http://blog.digitaltutors.com/subject/game-art/),

Sculpting (http://blog.digitaltutors.com/subject/sculpting-3d/),

Texturing (http://blog.digitaltutors.com/subject/texturing-3d/)

SOFTWARE

3ds Max (http://blog.digitaltutors.com/software/3ds-max/),

Maya (http://blog.digitaltutors.com/software/maya-coming-soon/),

MODO (http://blog.digitaltutors.com/software/modo/),

Mudbox (http://blog.digitaltutors.com/software/mudbox/),

Softimage (http://blog.digitaltutors.com/software/softimage/),

ZBrush (http://blog.digitaltutors.com/software/zbrush/)

By

Eddie Russell

From digital art to graphic design to texturing, Eddie contributes video training and articles that touchalmost every subject. He does everything. Except birthdays.

Latest Articles:

Substance Painter: An Intelligent Approach to Painting Textures(http://blog.digitaltutors.com/substance-painter-intelligent-approach-painting-textures/)

Look to Your Favorite Video Game for Creative Inspiration (http://blog.digitaltutors.com/look-favorite-

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video-game-creative-inspiration/)

Understanding the Difference between Texture Maps (http://blog.digitaltutors.com/understanding-difference-texture-maps/)

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8/11/2015 Know the Difference: Bump, Normal and Displacement Maps

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(http://blog.digitaltutors.com/cover-bases-common-3d-texturing-terminology/)Start Mastering Important 3D Texturing Terminology

(http://blog.digitaltutors.com/tips-creating-perfect-normal-maps-every-time/)Tips for Creating Perfect Normal Maps Every Time

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