Transparent spaceship - please help a newbie!

Hi All,

A brief explanation - I’m thoroughly enjoying Blender, and I know I have not scratched the surface.

However - for an amateur show I am putting together a scene where a spaceship flies past the camera, a planet in the background. I wanted some lens flare and thruster glow, and I am more conversant with Apple Motion for that. I did the whole scene as a QT h.264 file and all is well. Did flare and thrusters in Motion and used masks to set them behind the ship.

I want to experiment a bit, and so did a separate planet/stars background movie and then just the layer with the ship. I rendered the ship RGBA to several (Targa, Targa Raw, PNG) codecs and formats. When I put it into the Motion file it is see-through; I tried it with Shake also - same thing. I did it with Maya years ago and all was well, but I am older and more forgetful! I know I’m being dense, but can anyone tell me (in layman, new-to-this terms) what I’m missing for this operation?

PS - I know I can composite the whole thing in Blender, but that’s a stage too advanced for me just now. For the time being - what am I doing wrong with this exported setup?

Should be well explainded in Motion’s doc …

Thanks. I know I’m being dense, but I can’t get it to not be transparent - and I’ve read the Motion manual. I check as much as poss before bothering you good folk. I render rgba, drag in the targ sequence and even with premultiplied mix, I can see the background through the ship.

I appreciate the reply, but please could I have some suggestions of what I might do in terms of the render - I think that’s where I’m getting it wrong.


I think that what I need to do is render the ship with no sky. If I do it RGB, and remove "Halo and “Sky” from the render layers, I get just the ship, but the black background is ‘solid’

I’m sure I am just a couple of clicks away from getting it.

Any thoughts?

Under Render options panels, there are buttons ‘Sky/Premul/Key’ (B2.49) or popup menu with options ‘Sky/Premul/StraightAlpha’ ( B2.5x). Did you try settings other than default ‘Sky’? They are for keying purpose. And output should be set to RGBA.

Hi jawra,

I have tried it as premul and key (I’m on 2.49). I shall re-try in 2.53. I know I’m missing something in the mass of Z, Halo, etc.

I’ve tried rendering stripped down to the point where my smooth surfaces have disappeared - still the ship is transparent, and if I switch off Alpha in Motion, the background becomes solid black again.

Grrr (aimed at me and my stupidity). I shall have to learn the Blender composite nose system I think, to add bits and pieces, but I’d love to find out what I am doing wrong here.

If anyone can render an object (SOLID!!) without the background, could they post their render settings?

Here is .blend file with sample images for Sky/Premul/Key options - nothing else changed in default setup.
More problematic may be saving video sequence. Not many video formats/codecs support alpha channel. I’ve tried different formats in Blender with no success. As I found, QT h.264 doesn’t support alpha. Some guys mentioned about QT Animation codec but I didn’t try it yet - under Linux I have only Blender’s built in support for QT with no Animation codec, so I have to switch to WinXP with external codec.
You can save animation as .png’s and import as sequence of images or play with chroma keying ( like bluebox ) or give a try Blender’s node system - it’s not complicated.


T_B.blend (258 KB)

QT Animation codec supports Alpha but it requires standalone installation of Apple’s QuickTime.
QT has option to generate .mov file with PNG as codec so it includes Alpha.


Thanks so much for that info. I am trying your suggestions. I think (once this project is over) I’m going to give blender nodes a bash!

I went back to the cube and retraced my actions with the ship.

FWIW - in order to remove the stars, I was unchecking “halo” and “sky” in the layers box, and going for premul or key in the render box.

Based on the cube, and Jawra’s file settings - I did this: DELETED the stars (hit the “x”), checked “sky” and “halo” in layers, and in “render” went for “sky” - rendered to RGBA png file and the ship is SOLID!!

Thanks so much for the file. I shall - as I said - have an attempt soon at doing it all in Blender.