Field of regard and Visual image

Field of regard noun - All of the points of the physical environment that can be perceived by a stable eye at a given moment.

Visual image and field of regard are semantically related. In some cases you can use "Visual image" instead a noun phrase "Field of regard".

Visual image noun - A mental image that is similar to a visual perception.

Field of regard and visual image are semantically related. Sometimes you can replace phrase "Field of regard" with "Visual image", this phrases are similar.