Water reflections for montage?

[Rhodesy]

I am doing a montage of a bridge over a river and would like to show the reflections on the bridge in the water. Currently I have a plane in at water level that is reflective - with a slight roughness. What is the best way to extract that reflection in photoshop so I can blend it with the photo easily? Essentially I just want the reflection of the bridge and non of the rests of the plane which is bright and reflecting the sky. I dont think corona allows frontal mapping for projecting the background on to the plane which could have been an option. Im using the C4D version if that makes a difference. I am rendering out the reflection pass as part of my multipass.

thanks in advance

[maru]

Sorry, but I do not understand the description. My imagination is too limited it seems. :)
Can you post some images/screenshots + explanations, or an example of the final result which you would like to achieve?

[Frood]

Im using the C4D version if that makes a difference.

Does the C4D version also has the ShadowCatcher material? If so, look into it. It does what you described.

But for most bridge (montage) projects I´ve done, the rendered reflection was replaced in post or blurred like crazy anyway because it´s difficult to mimic the sometimes very special roughness/waves of the water. In some situations - depending on your photo - you may even be fine with mirroring your rendering + composing it onto the original water in post without computing water reflection (shadow is something different, you always need it).

And I´m surprised every time again how differently bridge reflections can get (subtile/blurry vs. strong/clear):

http://www.karl-gotsch.de/Album/Donau_A.htm


Good Luck

[romullus]

Essentially I just want the reflection of the bridge and non of the rests of the plane which is bright and reflecting the sky.

If you want that only bridge would be visible in reflection and not sky, then simply exclude enviroment from reflection, by enabling enviroment override.

[Rhodesy]

Thanks for the help guys its been a busy few days so just getting round to replying. I finished the job by just switching the reflection pass to soft light in PS and then painting it in. It kind of works but not the cleanest if I needed it. Romullus, just gave that a try in C4D and that looks like it would work, so essentially the plane is black apart from the bridge reflecting in it. Im sure I could manipulate that in PS more easily. Thanks for your help.