Difference between Normal Bump and Displacement Maps

In the world of PBR Texturing, many different texture maps are used to create a realistic material. Every map has its role to provide realism to the material. Some of these maps are Normal, Bump and Displacement. These maps are responsible to give an additional resolution or detail to the surface of geometry where the material is applied. Some of these details are real and some are just illusions.

Normal Map

Normal maps are a newer and improved sort of bump map. The first thing to learn about normal maps, like in the case of bump maps, is that the detail they generate is also simulated. There is no additional resolution or mesh data added to your model’s geometry. Finally, a normal map creates the sense of depth detail on a model’s surface, but it does it differently than a bump map. A bump map, as we already know, employs grayscale values to deliver either up or down information.

A normal map uses RGB data that matches directly to the X, Y, and Z axis in a 3D space. This RGB data tells the 3D application which direction the surface normals are orientated in for each polygon. The direction of the surface normals, also known as normals, tells the 3D software how to shade the polygon. When studying about normal maps, you should be aware that there are two distinct varieties. When seen in 2D space, these two varieties appear radically different. The most widely used is a Tangent Space normal map, which is mostly purples and blues. These maps are best suited for meshes that would deform during animation. Normal maps in Tangent Space are ideal for things like characters.

Object Space normal map is frequently used for things that do not need to deform. These maps have a rainbow of varied hues and somewhat better performance than Tangent Space maps. When contemplating utilising a normal map, there are a few factors to keep in mind. These sorts of maps, unlike bump maps, may be difficult to produce or alter in 2D tools such as Photoshop.

You will most likely bake a normal map using a high-quality version of your model. However, there are several exceptions for modifying these kinds of maps. MARI, for example, may paint the type of surface normal information seen in a normal map. Normal maps are quite well incorporated into most pipelines in terms of support. There are exceptions to this rule, unlike with a bump map. One of these is mobile game design. Only lately has hardware progressed to the point where mobile games are incorporating normal mapping into their pipelines.

Bump Map

Using computer graphics, bump maps create the illusion of depth and texture on the surface of a 3D model. Rather than having to manually create individual bumps and cracks, textures are artificially created on the surface of objects using grayscale and simple lighting tricks.

A bump map is one of the more traditional types of maps we’ll look at today. The first thing you should know about bump maps is that the detail they produce is simulated. A bump map does not add any additional resolution to the model. Bump maps are typically grayscale images with only 8 bits of colour information. There are only 256 different shades of black, grey, and white. These values in a bump map tell the 3D software essentially two things. Either up or down. When the values in a bump map are close to 50% grey, there is little to no detail visible on the surface.

Details appear to pull out of the surface as values become brighter (more towards white). In the opposite case, as values become darker and closer to black, they appear to push into the surface. Bump maps are fantastic for adding small details to a model. For instance, pores or wrinkles on the skin. They are also relatively simple to create and edit in a 2D application like Photoshop because they only use grayscale values. The issue with bump maps is that they easily break if the camera is positioned incorrectly.

The silhouette of the geometry that the bump map is applied to will always be unaffected by the map because the detail they create is fake and not real resolution or any geometry has been added to the mesh.

Displacement Maps

When it comes to adding detail to your low-resolution models, displacement maps reign supreme. As the name indicates, these mappings physically displace the surface to which they’re applied. In order to add detail based on a displacement map, the mesh is generally subdivided or tessellated so that actual geometry is generated. The amazing part about displacement maps is that they may be baked from a high-resolution model or hand-painted. Displacement maps can also be created procedurally using different tools. A displacement map, like a bump map, is made up of grayscale values.

So here’s the real kicker. While an 8-bit displacement map can be used, a 16- or 32-bit displacement map will nearly always produce superior results. While 8-bit files may seem excellent in 2D, when converted to 3D, they can occasionally create banding or other abnormalities due to inadequate value range.

Now, here’s the troubling thing about displacement maps. Adding all of that extra geometry in real-time is really demanding and taxing on your machine. As a result, most 3D programmes compute final displacement results during the render process. A displacement map, unlike bump or normal maps, will add substantial time to your renderings. As a result of this added geometry, the results of a displacement map are difficult to beat. Because the surface has been transformed, the silhouette reflects the new geometry. Before selecting to use a displacement map, you should always consider the cost versus the added advantage.

Utilizing these maps

In some cases, combining a bump or normal map with a displacement map on the same item may be possible. The ideal approach to do this would be to use displacement for large changes in geometry and then normal or bump for fine detail. Regardless of the map, you select, understanding how each map works and its benefits and shortcomings can only help you make a better decision. Finally, the map you choose should be the one that best meets the necessities of the situation you’re in.

We provide all the required texture maps for our entire library of PBR Textures and Decals. You can visit our library here.