Export 2D Camera Motion as a vector for Vector Blur Node

Question

I have this camera just "waveing" due to an s-shake (Built-In Function modifier for the rotation keyframing), and I need to use the motion of the camera to rotate and blur an image like a post processed motion Blur. I tried to use the vector Pass while rendering but this only works if there is an object moving in the scene. I don't want just to import the image as a plane and render with motion blur cause this won't be practical if you have muliple scenes. Basically something like this:

that is

a pass that can tell the compositor in which direction the motion happens.

Is there any way of doing this?

Answer 1

Here is what I did to get it to work. (I didn't add an explanation to my comment, because I essentially just did, what you described in your question.) Anyways, here it goes:

I'm using Blender 2.79.

My Scene only contains a camera and an image plane, which I added via "Images as Planes". Then, I added keyframes to the Camera Rotation. I modified X-, Y-, Z-Rotation with a Noise Modifier.

I turned off Motion Blur in the Render Tab

And here are the Render Passes I used:

Then, turn on Compositing under Post Processing.

This is my Node Setup to add the Vector Blur:

Which gives me this result:

Note, that the image plane is NOT moving.

Have a look at the blend file:

EDIT:

A little side-note, that I've just noticed:

When I look at the vector pass (by Ctrl + Clicking with Node Wrangler Addon) I only sometimes see the actual colors in the viewer. Other times the viewer shows nothing. But this seems to be only an issue with displaying it, because, when I left-click on the viewer, I actually get a values at the cursor position. This can also be confirmed by saving it out. - The I get this picture, even though the viewer shows nothing: