When identifying columns in a PDF drawing by color, I find some columns cannot be identified successfully.
After clicking Identify > Identification Options > Column Settings, you will find that the set value for Maximum ratio of long edge to short edge of column is 4. It means that when the ratio of long edge to short edge of column exceeds 4 (see the figure above, long edge is 1500mm, short edge is 300mm, so the ratio is 5, greater than 4), the column will not be identified. To identify the columns successfully, double-click to change the set value.
Note: The rule that the column will not be identified if the ratio of long edge to short edge exceeds 4 is embedded here because from the business perspective, if the ratio of long edge to short edge exceeds 4, the corresponding element is probably a wall.