Transparent reflections for 2D compositing

I’m trying to render shadows and a reflection with Alpha transparency so I can place an object in a photograph, I’ve managed to work out how to get the shadows transparent, but can’t get the reflections to work. If I have a reflection, I also get my dummy plane rendered solid?? I’m using 2.37a on Debian with the standard renderer.

Any Ideas? Thanks in advance.

In F5, Material buttons, Mirror Transp tab, use the “SpecTra” slider and try the “Add” one too, in small doses.

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Thanks for your help, but still no joy, do you know if Blender is capable of transparent reflections, that is rendered and then saved as a PNG with alpha?

I’ve tried everything, can’t get it to work. Shadows work by setting the Shadow only button on, but no reflection.

I’ve overcome the problem in the Gimp, but it would be nice to be able to output a file that was already transparent.

By “reflections” do you mean the specular highlights on the object itself, or do you mean light reflected from and/or thru the object onto other objects in the immediate surroundings?

My answer above refers only to the former and only with raytracing on. The latter is impossible in Blender but is possible in Yafray (called Caustics) and some other BMRT renderers.

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What I have is an object (a clients product) sitting on a dummy plane that represents the floor in my photograph, I’d like to render a reflection of the object on the dummy plane(floor) that can be used to make the composition look realistic. I can do this as a solid reflection then Gimp in the alpha values. But it would be nice to just do it all in a render, then save as PNG with Alpha.

Sounds like Blender Render can’t do it from what you’ve said, I’ll start using Yafray.

Thanks for that.
I’ll let you know how I get on over the next couple of days, I’ve not used Yafray yet.

:slight_smile:

That’s very possible. For the “dummy plane” just turn on “Ray Mirror” in F5 in the MirrorTransp tab and set the value with the “RayMir” slider. Turn on RayTransp and in the Shaders tab turn on TraShad and in F10 in the Render tab turn on “Ray”.

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Sorry, just to clarify, do you mean it is possible with the Blender Renderer, or with Yafray?

As I have my settings as you suggested, and I get my dummy plane and reflection rendered as transparent within Blender (that’s to say that other objects in the scene are viewable through the plane), but this does not give me an Alpha value for the saved image, so as to be able to compose the image on top of my photograph and have the floor showing through the reflection. The saved image is still solid? I hope this makes sense.

Maybe I’m just too lazy, and I’m expecting too much of the work to be done for me? I just assumed if it works with shadows, I should be able to get it working with reflections.

Here is an early version of the web site I’m working on, it may give you a better understanding of what I’m trying to achieve.

http://www.leafaudio.com/wip.htm

The remote control by the womans hands is the object I’ve modelled in Blender.

Cheers Andreas