Clarification on backplates and environments

[IceDiver]

Hey,

So I'm new to this software and am a bit unclear on the standard workflow used.
Do I always need to use a backplate when rendering an image, to me it seems the hdri environments supply quite nice backgrounds from time to time, and the ability to turn the environment around to match the model seems very nice?

If using a backplate is the preferred method, I assume you need to get an HDRI and a backplate of the same image? I read about rendering the image without the model to save the backplate that way, but what is the difference in doing that compared to just rendering away with the HDRI as the background? Also, is it possible to get HDRI + backplate packages somewhere, preferably free ones?

Answers much appreciated

[elliasp]

Well, about my work, I use backplate only if there is transparent material in the scene (like glass, for exemple... because background is very important for transparent material as you can guess...).

Most of the time, backplates I use and HDRI are not matching, except if I have no choice (CGI car photography... and even in this case, sometimes I use a Studio HDRI and a landscape backplate  )

You know what ? There is no rules : do what you want to do ! The most important is to concretise your idea (excuse me, my english is very bad ^^)

Have fun ! 

[jhiker]

As I understand it, the HDRI environment is generally chosen to provide the preferred lighting for the image.

The backplate is just a picture that hangs behind the rendered scene and can be something from the Keyshot backplate library or a picture file of your choosing (within reason). It's not compulsory to have a backplate - you can render with the HDRI in the background if you wish.

Oh - and check the 'HDRI' sub-section of the forum.

[akira73]

I have a problem using backplate image since without it I get different reflection on the glass, with it the reflections changes.

I wonder the hdri was the only thing affecting the reflections.

hope it is clear: rendering with hdri and no background I get an image nice with nice reflection but adding a backplate the reflections changes and the glass show some black areas.

[guest84672]

The reflection doesn't change, but depending on the geometry of the glass you may end with some black areas when using a backplate. Changing your camera angel may help.

[akira73]

I still have the same problem.
I'm rendering a glass bottle. Without the backplate and using an HDRI I'm having a nice render but when I simply drag and drop a backplate the render became darker and there is a new reflection on the glass (not a transparency of the image in backgroud, really a refraction ).
It make no sense if the backplate should not affect the render reflection and refraction...
take alook to the colored vertical stripe that appears in the image with the caustic backplate.

[guest84672]

Difficult to say - can you share the package?

[akira73]

http://ge.tt/8Px5pDL/v/0?c

[akira73]

any news?