Configure Measurement Properties ​

public void SetMeasureSettings()
{
    // Set the measurement scale in the PDF file to 1.0 inch.
    MeasureSetting.RulerBase = 1.0;
    MeasureSetting.RulerBaseUnit = CPDFMeasure.CPDF_IN;

    // Set the translation of 1.0 inch in the PDF to correspond to 10.0 feet in the actual object.
    MeasureSetting.RulerTranslate = 10.0;
    MeasureSetting.RulerTranslateUnit = CPDFMeasure.CPDF_FT;

    // Set the precision to 0.01.
    MeasureSetting.RulerTranslateUnit = 0.01;

    // (For enclosed graphics with measurable area) Set to display the area in the annotation appearance.
    MeasureSetting.IsShowArea = true;

    // (For enclosed graphics with measurable perimeter) Set to display the perimeter in the annotation appearance.
    MeasureSetting.IsShowLength = true;
}