I’ve recently installed Blender so I can render PNGs with alpha channels. Among the first things I did when I first loaded it was to set the format to PNG and RGBA. Low-and-behold, it rendered the default “box” scene on a transparent “chequered” background - Great!
However, I can no longer recreate this. I’ve tried almost every button and option on the buttons window, but all it does is render on a black or blue background. I can’t get it to render an image showing transparency with a chequered background. Even the saved PNG has no alpha channel in it.
I’ve even installed Blender on a new PC and can’t re-produce the original settings that made the transparent background work. I’m close to tears with frustration now and beginning to wonder if I dreamed the whole thing!
If your BG is anything other than black and it renders black, then you have succeeded. You have to set render RGBA and under the Shading tab set Alpha to straight alpha. The image will render with a black BG but when you save it out as a PNG and load it into Photoshop, Paint Shop, GIMP, heck even the compositor, it will have the checkered BG that you are used to seeing. You could save the image to your desktop to see that the BG is actually transparent, but only if you want to. Of course what I have told you is in Blender 2.5x, but give it a try. I was confused too, and don’t quite understand why Blender doesn’t follow the same convention of the checkered BG for this option.
When you are viewing your rendered image in the UV editor window, on the menu bar there is a button “draw image with RGB colors and alpha transparency”. If you have an RGBA image it will show the good ol’ checkerboard pattern. Is that what you are looking for?
if you use the newer blender-versions, like blender-2.56
you do a normal render,
press F12 … or click on “image” (with the photo-icon) to do the render.
A window pops up or (default) the rendered picture is shown in the mid
of your screen. Its the picture with a shaded background, the normal
gray of the default startup-scene with the cube.
This window has some buttons in its menu-line (normaly at the bottom).
Right at the side of the “image-painting-button” (brush-symbol) there are
more buttons. and if you click on the ?second-one with alpha-transparency to show
-… then the picture changes from its gray-background to the alpha transparency
background.
Now you only have to save this… ? How?
In the menu-line is left aside from those buttons the “Image” pull-up-menu with entries for “Save a Copy”, “Save As” —
and shure! you need to use a graphics-image-format like png, that can save transparency.
Problem solved. It was a mix of stupidity and confusion on my part; apologies… (it was the early hours of the morning, to be fair)
The version of PSP on my desktop didn’t load PNG alpha channel properly. I had 7.0 on my desktop and 7.04 on my notebook. So yes, the images were being rendered with transparency after all.
I also think I might have dreamt that the quick-render (F12) window displayed the chequered background in Blender? I’m using 2.49b Win32.
So if I’m new to Blender, I should start off with the newer version if the interface has changed, right?
I did notice in version 2.49b that pressing the ‘A’ key whilst in the render preview will display the transparent alpha-channel. Also, left-clicking will display the details of every pixel, incliding the alpha and z-index. Very handy.
Again, thanks. I can now move on until I hit another problem, heh.
Of course what I have told you is in Blender 2.5x, but give it a try. I was confused too, and don’t quite understand why Blender doesn’t follow the same convention of the checkered BG for this option.