refraction channel

[Bernhard S]

hello all!

 

if i save a image as an exr file and define a refracted channel in the background settings i can't see any "true" reflections of build geometry ,  for example in a glass wall. shadows of build geometry on transparent materials (glasswall) of build geometry are visible, reflections are not.

 

am i doing something wrong?

 

thanks!

 

bernhard

[Roy Hirshkowitz]

Hard to say without seeing the actual model and some pics. -- .exr and .hdr format can only save luminance data-- so any data such as RGB pictures cannot be saved in this format. The only backgrounds which work here are HDRs or Auto Sky.

Your best bet is not to mess with the refractive channel when you're first getting started. This is an advanced feature that is hardly ever necessary. It's best to return to one of the presets and start from there.

Having said that, it is possible that there's a bug here. The only way I'd be able to evaluate it properly is if you were to send the model (using Support->Upload a File above). Include detailed instructions for how to reproduce the problem in the Comments section.

[Bernhard S]

hello roy!

maybe the screenshot of the exr file is helpful too,...

[Roy Hirshkowitz]

It helps a little-- it's still very hard to understand. I assume this is an .exr w/ alpha channel? I'd still recommend going back to basics here.

[Bernhard S]

yes, it is an exr file opened in photoshop.
the reason why i want to use this feature, and this maybe helps to understand my question, is to create a semi transparent alpha channel that, for example, could be used to change the background image in photoshop. would be helpful, for example, if you render a interior view of a shopping mall with a huge glass roof. This way you could change the background image ("behind" the glass roof) and still have all reflections of the shopping mall in the glass roof,....
thanks

bernhard

[Roy Hirshkowitz]

Not a bad application-- you don't have to change the refractive bg for this-- just leave it as the default and save as an .exr w/ alpha. Whether the reflections are visible will depend on a variety of factors-- for more control you may want to save as an .nXtImage. The alpha channel can be saved separately here and edited in photoshop-- this may help bring out reflections.