adding a moving car

If you want to insert a shot of a car driving on a street but you have no car you have a couple of choices. You can shoot a miniature, use a 3D model, animate a cartoon car.

All three of these methods require careful planning, an understanding of the relationship between camera position and perspective, and lighting and compositing skills. The amount of work required is inversely proportional to the quality you want to achieve. Before I go into detail, what is your experience level with photography, film making, After Effects and 3D apps?

The basic procedure would be to plan the shot carefully, set up the camera in the right position to capture the scene without the car, figure the angles involved and then either shoot a toy car on a background you can easily remove, create the 3D model, or animate a drawing of a car that matches the angles and camera movement in the original shot. If there are any foreground elements in the original shot that the car would pass behind you'll have to separate those elements from the rest of the footage by rotoscoping or simple masking and then put them above the layer with the car.

I hope this helps. Let us know what you know how to do and we can help you plan something that you can successfully complete. The only thing I do know for sure is that if you don't plan and prepare you are very unlikely that you will have any luck creating a believable shot.

If your shot is from the side, this would be fairly easy to do. Get an image of a car, cut it out in Photoshop (or mask it in AE), then animate it driving from left to right in AE. (Don't forget to add things like leaning forward as it stops and backwards as it starts moving again (by slightly animating the rotation).

If you have a wider shot or a shot at a different angle, things might be a lot trickier.