Bump

Realsoft Graphics Oy		Bump
	VSL Objects

A Bump object uses a bitmap image to define a 'height transformation' to its output channel. This transformation is computed is such a way that, when assigned to the 'Bump normal' channel, the surface appears bumpy. The controls of a bump map are:

File name: The name of the image file used for bump mapping.
Tile X and Tile Y: These controls repeat the bump map pattern on the surface of the target object.
Flip X and Flip Y: These options work in combination with the tile options. If Flip X is set, every second tiled bump area is inverted horizontally, so that the left and the right edges of adjacent tiles always match. Flip Y does the same in the vertical mapping direction.
Bleed X and Bleed Y: Bleed option extrapolates edge values outside bump mapped area.
Interpolation: Interpolation type defines the shape of the bumps. Linear interpolation produces sharp ridges and peaks, whereas Cubic produces very smoothly varying bumps. Bi-linear and Quadric are between these two.
Compute Direction/Height: Compute Direction is the suitable operation mode when a bump map is used in a Surface properties shader for direct bump normal manipulation. Compute Height is designed for use in a Surface geometry shader.
Bump height: Defines the height of bumps. In Compute Height mode, the measuring unit is meters, and therefore quite small values are often sufficient.
Smooth: A smoothing filter. This feature eliminates pixelization of high resolution bump maps. The measuring units is the proportion

radius of the smoothing filter/image width

Therefore, quite small values are usually sufficient. Level 0.01 smoothing in a 500*500 pixel image uses a 10*10=100 pixel filter for smoothing.
Binding: Binding controls are included in a separate tab when a bump object is selected. The tab displays a list of data channels, which are included in the selected image. By default, the first data sub channel (red in a usual color image) defines the bump height, but other channels can be selected as well.

Animation tab: This tab includes controls needed when using an animated image sequence for defining the bump map (or any other texture map type). This means that the program automatically loads a new bump map in every rendered frame.

Animation Type: This option defines whether the bump map animation is on or off, and how the image index should be computed. The following alternatives are available:
- None:Animation disabled. The first frame of an animation file or the specified image without index changes is used.
- Automatic: The image index is computed using 'Repeat', 'Base index' etc. options automatically. By default, the full image cycle is used repeatedly.
- Key Frame: The image index is computed from user defined key frames. Index does not change before a key frame sequence is recorded using the 'Current Index' field.
Current Index: Shows the texture index which will be used in the current animation frame. If 'Key Frame' Animation type is selected, you can enter indices to this field in animation recording mode and hence key frame an arbitrary order for texture indexing.
Base index: Defines, what is the index of the first image of the bump map sequence (usually 0 or 1). The value can also select the start of a sub range of a bump map sequence.
Frames: Number of map images used for the animation (usually the total number of images in the map sequence). The images are selected starting from the base index. For example, consider a ten image sequence named as 'map0', 'map1', ..., 'map9'. If 'Base Index' is 3 and 'Frames' is 5, the index sequence will be 3, 4, 5, 6, 7, 3, 4, …
Repeat: Activates repeated cycle of bump map images. First image is loaded again after the last defined image.
Ping Pong: Activates 'ping-pong' style repeating of bump map sequence: bump index increases until the last index is reached, then it starts decreasing until the first index is reached, and so on.
Reverse: Inverts the direction of bump map sequence.
Format Type: Defines how names of separate images are indexed (a sample name is displayed below). When 'Default' indexing is set, the number of digits can be defined with the 'Digits' slider. When 'Custom' indexing is selected, any kind of indexing convention can be defined using the 'Format string' field.
Digits: Number of decimal digits for image index. The value controls zero padding for small indices.
Format String: Custom indexing format. The string follows the standard C language 'printf' conventions.

	Note
Automatic texture indexing changes the index in every frame, field and motion sample, so that texture animations are motion blurred as well. Other kind of behavior can be defined by animating the texture index by key framing. The choreography window makes it possible to modify the animated indexing in a highly flexible manner: the index curve can be point edited, the time line can be moved in time, scaled, repeated, etc.

Note

Automatic texture indexing changes the index in every frame, field and motion sample, so that texture animations are motion blurred as well. Other kind of behavior can be defined by animating the texture index by key framing. The choreography window makes it possible to modify the animated indexing in a highly flexible manner: the index curve can be point edited, the time line can be moved in time, scaled, repeated, etc.