alpha or opacity map

[KrollMoll]

Hello everybody,

Does anyone know where I could find a good tutorial to create alpha or transparency map for rendering hairs...

Thanks in advance.

[PlatnumK]

Not sure if this is any good

[KrollMoll]

Thanks for this verry interesting and usefull link but what I would like to know is the way to CREATE a alpha or transparency map...

Any idea?

[Marcel2586]

a transparency map or alpha map exist 9 out of 10 times out of two colors, black and white.
The black makes sure that the part is invisible and the white is visible. A nice example is leaves of trees.
It is almost impossible to model all the leaves and there comes transparency maps or alpha maps in handy.
The leaves are small square planes with a leave texture on it and with a transparency map.

The transparency map

the texture map

You can trace a texture map in a paint program and make it white and the rest black.

[KrollMoll]

It means all hairs transparency maps have been ceated by hand?
There is no possibilities to generate it with a program as for bump maps?

[Marcel2586]

yes it can with Adobe Photoshop or Gimp. turn the texture into black and white and then lower the colors to two colors, black and white.