NormalMapper

Without a cage, the rays are cast from the low-poly mesh to the high-poly one (in both directions along the normals of a low-poly). It is done to determine what point of a high-poly mesh (full geometry of which allows to calculate per-vertex normals) corresponds to a low-poly mesh point. Whatever point is intersected first, it gets to be baked into the map. However, if there are complex geometry details in the high-poly model or overlapping surfaces, the first met point may not be a proper one. Instead of baking an outer surface, an underneath one that is closest to the low-poly mesh will be baked into a map.

A cage allows to avoid such situations. When loaded, the rays are traced from it rather then from a low-poly mesh.

• A cage mesh is usually a low-poly mesh slightly bloated to be bigger in size and cover both a high-poly and a low-poly meshes. Though even a simple box would do for a cage.
• It should not necessarily cover all volume of the mesh. The cage can be partial - only above such surfaces where complex geometry details are found.

Let's take an example as illustrated above (in section): we have a low-poly mesh (a simple plane) and a high-poly mesh, which has details above its surface. We can also load a cage that is above both a low- and a high-poly mesh.

Without a cage rays will be traced from a low-poly surface (from underneath) and all details will be ignored.	With a cage rays will be traced from the cage surface (from above). All details will be properly baked as they are the first surface met.
Normal mapping without a Cage	Normal mapping with a Cage

Level. NormalMapper automatically normalizes the displacement range from 0 to 1 (255 gradations for 8-bit texture). What height in units will be equal to the maximum 1, is controlled by the Level parameter. All heights above it are cut out and not baked into the texture.
Level allows to create textures for several meshes relative the same height scale. It is important when one object is represented as separate meshes with different textures.

• The Level is measured in units from the zero (in both directions for a height map; in one direction for a parallax map). All heights that fall outside this range are cut off. Changing the Level does not affect the zero value in the texture:
  • In the parallax map, zero (values higher then a low-poly surface) will still be the same white. Only the range
  • In the height map, zero is grey color that equals 128. The Level will not change it. It will only affect negative displacement (dark grey in range from 0 to 127) and positive displacement (light gray in range from 128 to 255).
• By the value of 0, the real maximum height displacement between a low-poly and a high-poly mesh will be used as texture pure white (or pure black, depending whether it is above or below a low-poly mesh).
• The higher the Level, the fewer gradations will be left for the actually represented height range. The resulting texture will be non-contrasting. It is strongly recommended to set the Level sufficiently low.
• The real displacement value between the low-poly and a high-poly meshed is displayed in the Info after NormalMapper was once run. It can change slightly with different texture sizes, because of different sampling rates. The real displacement value can be used as a reference point to set the Level.

For example, if a height map should be created basing on this high-poly and low-poly meshes:

Changing the level will bring the following. Note that the zero level at the middle did not change, only the peaks are baked differently:

Level = 0. Real displacement is used as max.	High Level.	Low Level. Heights were cut off.

Clamp parameter allows to cut off displacement values that are above the specified line within a set Level range. (See illustration above).

• By the value of 0, no clamping is done.
• The Clamp parameter is in effect only when it is lower than the Level. The maximum height (1 in texture coordinates) relative to which displacement values are normalized stays the same, while heights outside the Clamping range are cut off.

Clamp is lower than Level.	Even lower Clamp. More heights are cut off.

How to use Level and Clamp parameters for baking several meshes:

1. Load the first low-poly and a high-poly meshes.
2. Test run the calculations (for faster test, choose smallest texture size). Note what the maximum Displacement value between a low-poly and a high-poly is:

   

3. Repeat the same actions for all other meshes.
4. Choose the mesh with the highest displacement.
   • Set the Level value close to the real displacement, for example 9.6 units.
   • Set the required texture size
   • Click Run.
5. For all other meshes, set the same Level, for example 9.6.
6. If for any of the meshes it is required to clamp unnecessary heights, set Clamp value lower than the Level, for example to 8 units.Everything above this height will not be baked into the texture.

• The lower the size of the textures, the more visible darkening along the seams is. Increasing Extrusion parameter may help in this case.

Extrusion = 0 pixels	Extrusion = 4 pixels

• Parallax map — with _p
• Height map — with _h
• Surfaces texture — with _s

A saved normal map can either saved as a three-component (RGB) texture or a two-component (RG) texture if the Two component option is checked. Two-component map is not for further editing: it is intended to be loaded and used in the engine as it was saved. Two-component maps also cannot be stored in jpg format.

Three component normal map	Two component normal map