How should a horizontal reference line be drawn in an isometric drawing?

In isometric drawing, horizontal reference lines are critical for maintaining the proper perspective and proportions of the object being represented. These lines are drawn parallel to the ground line, which establishes a consistent baseline for the dimensions and angles of the structure.

By using a horizontal reference line that is parallel to the ground line, the object can be accurately depicted in three dimensions. This technique helps convey depth and volume effectively in isometric views, as it aligns with the isometric axes, making the overall structure more comprehensible.

Using a reference line at a random angle or not including it at all would lead to confusion and misrepresentation of the object’s geometry. Therefore, drawing the horizontal reference line parallel to the ground line ensures clarity and precision in the isometric drawing.