R

Relative height
A depth cue used to bring out the difference in height depending on the size of the objects.
Relative size
A depth cue used to bring out the difference in size depending on the placement of objects.
Resolution
Resolution refers to the number of pixels in an image.
Raster format
Raster format or bitmap format refers to closely spaced rows of dots forming an image on the computer screen.

S

Sketching
A freehand drawing with very little detail that acts like a preliminary drawing.
Subjective drawings
Drawings that convey the feelings or emotions in a cartoonic manner.
Space
The area in which objects are located.

T

Two-point perspective
The perspective in which receding lines in a picture plane meet at two vanishing points.
Three-point perspective
The perspective in which receding lines in a picture plane meet at three vanishing points.
Texture gradient
A depth cue that brings out the smoothness in texture as the object goes far away from the viewer.

3Dimensional art

Sketches that are depicting in a life-seeing way instead of flat are referred to as 3dimensional art.