[JTB]

http://www.tepavicharov.com/scripts.html
Check the last one,
Render black&white image where the selected objects are white and the rest of the objects are black. You can render also an animation. The script don't affect the scene materials, lights and render settings.When you press the "Render Mask" button you will be asked where to save the image(image sequence).

I think it can be useful and of course fast with noise-free result.
There is also a tut video.

[Bubbaloo]

I don't understand why you would need a script for this when rendering with Maxwell. Just hide the objects you need to, and render alpha (animation too).

[zdeno]

time is money ... that is an answer .

I rendered alpha using scanline render and it was faster 10 times and noise free.
because rendering alpha with cooperative mode in 1.7.1 is a joke.

[JTB]

Exactly, really fast and noise free...
I don't NEED it, but I like it and I could use it...

[Bubbaloo]

time is money ... that is an answer .

I rendered alpha using scanline render and it was faster 10 times and noise free.
because rendering alpha with cooperative mode in 1.7.1 is a joke.

But when rendering an alpha with a different engine, don't you run the risk of non-matching image output (camera/perspective and antialiasing)?

[JTB]

But when rendering an alpha with a different engine, don't you run the risk of non-matching image output (camera/perspective and antialiasing)?

That's why I ask if it is ok to use it!

[zdeno]

of course ... especially when DOF is very "high" it is useless

but for archviz purposes (my main interest) when using F-Stop 16 it match almost perfectly.