Hasta La Motion!

I have a big panorama let say 8000×3000, i put it on a card and then a 3d scene, a camera, a constant and a scanline render to shoot the panorama in pal (768×576).
I set the constant to 768×576
no problem everithing is fine.

Now i have a plate with a blue screen that i need to track (nodal pan and zoom), i put a track node. The track works very well.
I put a transform node after the scanline render.
I link the tracker to the transform node

It works fine, the image follow the track but….

I have black area around the 768×576, which is normal because, i have set my constant to this value.

Is their a way to avoid this, to see around the scanline render, or to transform my 2d data
in a 3d space and put it on my camera

thx in advance

I put a merge after the scanline render that i connect to the plate.