Render crops image from compositor I made a 3D tracking, and noticed that after rendering the image is cropped. I got the camera through the 3D tracking. Why is this happening and can we fix it without making new 3D tracking?

Here is a screenshot at the top is the compositor, and below is render:
When compositing a render over an image you have to make sure that your render dimensions for the scene are set to the same size as the background image.




Your other option (say if the picture quite large) is to scale the picture to match the render size.  

That can be done by adding a Scale node set to Render Size, which will give you a node setup like this.