Sorry, that answer was for Iaminnocent.
Anyway, if you want to use Blender, you could just position the camera so that it renders a fraction of your image by moving the camera closer to the models. Then move the camera in a planar fashion always rendering at 10000x10000. You can get infinite resolution that way.
For example, place camera at x,y = -1,1 render at 10000x10000
move camera to x,y = 1,1 render
then x,y = -1,-1 render
finally x,y = 1,-1 render
Then you have a 40000x40000 image. If the camera is skew, i.e. not aligned with any axis then you would either have to calculate the positions or perhaps move the camera in its local axes.
Note, the above example is fairly meaningless, I was just explaining how you might move the camera. You have to make sure that the views are close enough together or you won’t be able to join them up later. It’s probably ok for them to overlap as they should merge perfectly. You could clean up any mistakes in a 2d image editor.
Something I’m curious about is why 2D images need such high quality when IMAX cinema quality is only 4096x2048.