Adding CG elements over real footage

Hi all, this is my first post here. Just wanted to mention that.

Now, I HAVE used the search function, and I found a few relevant topics, but none of them really gave me a full answer. To what? Well, here’s my problem.

I’ve just started trying to add in CG elements to real-time footage, with a simple test movie of my book shelf. I have the shelf movie, tracked it with Icarus, and got the camera motion right. Then I added that cute little Blender monkey into the scene, added a plane for the shadows to be cast onto, and rendered it with ambient occlusion.
Great!
So… how do I actually overlay the monkey onto the footage of the shelf? Someone suggested I render it with an alpha channel. This means using .tga output, right? So I did that, but I really don’t want to have to manually import almost 70 .tga images into the sequence editor. Can I put them into a movie before putting them in Blender, or will they lose their alpha channel?

As you can tell, I’m a little bewildered about rendering… :frowning: I’ve been using Blender for about a year, but mostly focusing on modelling.

You can import your 70 .tga’s very quickly. In the sequence editor Add->Images, navigate to the directory and RMB-drag over the filenames you want. Click Select Images and place your strip. Then combine it with the live footage strip using an Alpha Over effect.

Aha. Thanks for that… that makes life much simpler :slight_smile:

Now, I guess this is a newbiosh question as well. When I render the .tgas, I should use the .tga output type, Key instead of Sky, and the RGBA mode. Anything else? The images I rendered before, once added into the sequence and an Alpha Over effect added, are appearing just like I rendered them. I have a suspicion that I didn’t use any special settings…

Looks like you did everything right, Key or Premul + RGBA preserves alpha in your .tga file. What exactly do you mean, they are appearing just as you rendered them?

Here’s an example .blend of how to do the same thing using the new composite nodes in 2.42

Mike

Looks like you did everything right, Key or Premul + RGBA preserves alpha in your .tga file. What exactly do you mean, they are appearing just as you rendered them?

In the renderer, I had a white background set, and it appeared like that - no transparency. But that was because I didn’t render it with any.

Anyway, it’s all solved now - and the monkey head is sitting comfortably on my bookshelf, except for a little slide which I blame on gravity :wink:

mstram: Thanks for that. I’m using 2.41 now, but I really should upgrade soon. I assume the nodes really are much better than just using the sequence editor.

you can also output a quicktime with tga compression and have it set to rgb and alpha…no images to resequence and the file size is smaller