Avoiding Duplicate Shape Counts in CAD Reader

In construction drawings, drafters often use very similar symbols with only minor modifications, such as adding a line, a letter, or a small shape to represent different items. For example, a one‑way switch and a two‑way switch may look almost identical.

When CAD Reader identifies shapes with nested relationships, if no filtering condition is applied, the software will search for all specified shapes of the same size, shape, and dimensions across the drawing. This means both standalone symbols and those embedded within other symbols will be recognized, which can result in duplicate counts.

To address this, CAD Reader has introduced a filtering feature that automatically excludes shapes already identified and counted. This prevents replicated counts and ensures accuracy, especially for electrical or trade symbols that share common base elements.

Example Scenario

A quadruple two way switch contains the shape of a triple two way switch. The quadruple two way switch, triple two way switch, and double two way switch all contain the single two way switch shape.

If you identify the single two way switch first, the software will also count all symbols that contain it, inflating the results.

Recommended Identification Sequence

1.     Identify the most complex shape first, such as the quadruple two way switch

with the most lines.

2.     Next, identify medium complexity shapes, such as the three-way switch.

3.     Then, identify moderately simple shapes, such as the two-way switch.

4.     Finally, identify the simplest shape, such as the single pole switch.

Key Principle and Outcome

Always identify complex shapes first, then simple ones. This progressively excludes nested symbols, leaving only the true simple shapes at the end. Double check counts after each step to confirm accuracy.

Tips & Notes

The filtering function “Remove overlapping shape from result" is enabled by default. If you prefer not to use filtering, you can manually uncheck the option. This method ensures each symbol is counted correctly without duplication, reducing errors in quantity take offs and improving efficiency.