Blender

Background images are applied on a “per camera” basis. You can set a background image for your camera by:

1. Selecting a camera
2. Toggle on Camera Settings -> Background Images
3. Go to Camera Settings -> Background Images -> Add Image and navigate to the image you want to display

You can change the aspect ratio of a background image by changing the Output Properties -> Resolution x/y.

You can toggle global wireframe with ⇧ + Z.

You can move the viewport zoom centre while in camera mode with Hold ⇧ + Pan MMB. This only changes viewport display of the camera view, does not effect camera position of zoom, its purely for checking and aligning things in the viewport while in camera mode.

You can projection extract a rectangular texture from an image by:

1. Adding the image with the element you want to map as a camera image.

You can open UV mapping menu by pressing U when in Edit Mode.

You can project from view by going to UV Mapping -> Project From View.