The Faro Focus3D is a new long range scanner that NeoMetrix Technologies will be representing. The manufacturer of the Focus scanner claims that the Focus has an accuracy of 2 millimeters. From firsthand experience with the Focus scanner, scanning engineers have been very impressed with the accuracy of the scan data and have suspected a higher degree of accuracy on items that are less than 10 meters than what the manufacturer has declared. This report is designed to display the scan data that the Focus gives and compare it to that of the Creaform MetraScan in order to find the true accuracy of the Focus scanner on smaller items. Because the MetraScan is a highly respected and well known three dimensional scanner that has been calibrated and tested using NIST standards of accuracy, this report uses the MetraScan data as a nominal (or reference) data set.
The scanning object selected for this report is the mold of a boat hull. The hull mold was scanned with both the MetraScan and the Focus scanner, as seen in the image below.
The blue hull on the left is the MetraScan hull, and on the right in yellow is the Focus hull. The two hulls were aligned in Rapidform XOR in order to take accurate, consistent measurements. A series of measurements were taken in the comparison, among which are standard marine measurements such as the beam, LOA (length over all), deadrise, and gunnel height. All of the different measurements and their numerical values can be seen in the table below.
All of the measurements in the table above are in inches, with an exception of angular deadrise measurements. The LOA is a very important measurement for any marine vehicle, and as you can see the boat that his mold produces is slightly longer than 21 feet. Even though the measurement is very large, the difference between the scanners was less than a tenth of an inch, as seen below.
The image on the left is the MetraScan LOA, and on the right is the Focus LOA measurement.
Next on the data spreadsheet are the four beam measurements. In the image below, both the MetraScan hull and the Focus hull are aligned together with the four different planes that were used to measure the beam in the four positions.
Position 1 is at the stern, and position 2 is 48 inches in front of position 1. Position 3 is close to the middle of the boat and position 4 is the plane which is nearest to the bow. Positions 3 and 4 were the lesser accurate of the four beams, yet they were both within 40 thousandths of an inch (or one millimeter), of one another. The cross section displayed below is that of the beam position 4.
The difference in the two beam measurements was a mere 26 thousandths of an inch, which is equal to 0.66 millimeters.
Next on the list is the deadrise measurement. The deadrise is a measurement of the angle from the horizon to the primary surface line of one side of the hull as seen below.
The deadrise is typically measured near at the transom, so the deadrise measurements in the report were taken from roughly 27 inches from the transom. The deadrise measurements above were labeled in the spreadsheet as “Deadrise 2”, and they differed by less than one tenth of one degree.
Finally, the height of the hull side wall was measured at the same distance forward from the transom as the deadrise was (27 inches). This particular boat model has a flat spot on the underside of the hull at this position, so it made for an easy reference to use to measure the height of the hull at that point. As displayed below, the two scans differed by only only 49 thousandths of an inch.
In conclusion, despite the wide range of different measurements taken, the average difference in length of all linear measurements was 0.035 inches, or 35 thousandths. When converted to metric units, this is a mere 0.89 millimeters. This is significantly better than the supposed 2 millimeter accuracy label that the Focus received from the manufacturer, thus showing on parts less than 10 meters a much better accuracy than 2 millimeters can be achieved when using the Faro Focus long range scanner.