BG Filter shows images on large sphere(s), which works as backgroud of the scene.
The size of sphere is determined by scale factor, and you can set multiple BGs with different scales like onion skins.
For example, star field on a texture of Milkyway.
Usually, scale factor should be large number, (but not larger than clipping distance.).
The images below are taken with small scale factor for clarity.
In default, these textures are aligned along z-axis. You can rotate the coordinate by editing R(otate) parameter.
Star filed is very popular backgroud, especially for astronomical situations.
This filter makes randomly located stars on the sphere.
With alpha values larger than 1, you can set the brightness of the stars larger than 1.
This feature is sometimes useful when you have editing exposures.
This filter uses image file(s) testure for background.
Currently, two type of mapping is inplemented.
This mapping uses two fisheye images to map all sphere. Each image covers top and bottom half of the sphere.
This mapping uses a image with polar coordinate. This format is very popular one for mapping on a sphere, like planets.
A below-left texture (jupiter) would be mapped like a right image. Note that the texture is mapped to "inside" of the shpere. The jupiter is inside out (or should we call outside in ?).
If filenames are set to be the special word "NONE", the textures would be deleted.
Instead of two fisheyes. Use one single 2:1 image with two fisheye appended horizontally.
This is the same format to the Dual Fisheye in View and Camera Configure.
Select direction of mapping from +X, +Y, +Z, -X, -Y, -Z.
Sequenctial images can be used for texture. Set file name with printf format like BGImg%04d.png
This filter uses a color curve as the source. In even mode, the color curve reflects on z=0 plane (like below image).