Thank you very much Alan, i was able to do it thanks to your explanation.
I needed something like that, step by step, because i opened photoshop today for the first time and i know nothing at all about it!

Once again thank you.

This forum is the best!

well...i can see it...
but if you can't see, in the alpha the blue is black and everything else is white.

i think it's simple... when i do a render, vray creates an alpha image and an normal one, i'll post them, so that you know what i talking about.
what i want to learn is to keep only the render part(the white on the alpha), remove all the rest(the black on the alpha)and place a new image on the background.

Alpha:

Picture:

thanks

thanks for the link, i'll take a look. i don't know anything about photoshop..

Hi everybody, i'm trying to learn a bit of photoshop, i want to change the background of a vray render i've done.
i never used photoshop before. Does anybody knows a tutorial showing how to do this?
thanks

again thanks for the reply and advices, my problem is that i don't know anything about photoshop, you know any kind of tutorials regardings this line of work?

regards

but as you can see in the image sample, it's not that much grass that is in the scene...is this normal? is there anyway i can override that memory limit?
this is a small project, i think this shouldn't happen, what happens if i'm doing a bigger one?
also i'm thinking of changing my quadro fx 570 256mb to a gfx295 1gb(1800 something), do you think will do any good?

thanks for your patience and advices

in that scene i'm trying to render, yes. plus some grass, but not so much. i'm working with windows 7 64bits, so i don't know if the limit is valid here.

about the displacement, turning it off will get the renders done.

i've been trying some different resolutions, and for 800x600 the cpu is on 100% and MEMORY on 72%(2.91mb) and usually i get the render done.
for 1024x768 cpu is also on 100% and MEMORY on 73%(2.94GB) and it crashes
i used the exact scene for both of them
this is the error i get:
Problem Event Name: APPCRASH
Application Name: SketchUp.exe
Application Version: 6.0.1099.0
Application Timestamp: 46ddd44e
Fault Module Name: VRayForSketchUp.so
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 46451428
Exception Code: c0000005
Exception Offset: 00342c62
OS Version: 6.1.7137.2.0.0.256.1

sample of the scene i was rendering: