As the distance between an object and a viewer increases, the contrast between the object and its background decreases, and the contrast of any markings or details within the object also decreases.
The colors of the object also become less saturated and shift towards the background color, which is usually blue (but can be other colors).
Based on this: objects appear smaller as they move further away from the viewer.
Includes 1-point & 2-point perspective*
*goes up to 5-point
1-point perspective—
Horizon line + 1 vanishing point
Whole sides of object (horizontal & vertical edges) are parallel to picture plane.
Examples of 1-point perspective:
2-point perspective—
Horizon line + 2 vanishing points
Vertical edges are parallel to picture plane.
Only vertical lines are (truly) parallel
Examples of 2-point perspective:
#1: Introduction to one-point perspective
#2: Train your eye: perspective practice
#3: Train your eye: eye level
Optional: This video textbook is a helpful resource if you want to check it out. It was made for high-school age students, but the information is good for all ages. (Note: you can click to specific "chapters" by the timestamp.)
Linear Perspective Video Textbook: https://youtu.be/67_Xeq3AEY8