Image display system, remote operation assistance system, and image display method

An image display composite system, comprising:

• a work machine that has an actual machine image capturing device, an actual machine distance measuring device, and a work mechanism;
• a remote operation device that has an output interface and is for remotely operating the work machine;
• and
• an image display system, wherein
• the image display system superimposes, on a work environment image representing a situation of a work mechanism constituting a work machine and an object present around the work machine that is acquired through the actual machine image capturing device, an index image indicating a second index point resulting from a first index point of the work mechanism being projected onto a surface of the object, whose three-dimensional shape is measured through the actual machine distance measuring device, in real space, and outputs the work environment image on which the index image is superimposed to an output interface of the remote operation device.