   a4 paper and camera
  Hy.I have a lot of architectural 3d model in real dimension(all in mm)and i would create a camera like the a4 paper that view from the top of the camera, and i would view all the a4 in the scene from the camera.How i can set the camera parameters like in the real world?thanks.   
  I don't think you can do that. I mean there's no reliable way to determine the exact sizes of the monitor. You have to know that in order to display your stuff in 1:1.If that's you are asking...   ;  just draw the a4 paper in the position (0,0,0)Set the camera position to (0,100,0) and to look to (0,0,0);If you still cant see the whole paper set a higher y-value to the cameraP.S. You will to set aspect ratio that fits with the paper   ;  Did you mean you want to fit the whole A4 to the screen?Anyway, it's still not clear for me what you want to achieve. Do you want a 2D view of the draft or something? Please clarify.   ;  If you want it to look like a diagram, you'll also want to use an orthographic projection.   