4.2 Scan Results
The 3D scanning methods both succeeded in generating the required data points as specified in Table 1. For our test curb cut on the south-west corner of Broadway and 26th, the Structure Sensor and P40 both acquired comparable ramp width measurements. Compared with the hand-measured width of 42 inches, both methods were judged to have satisfactory data quality on this simple lateral measurement.
As noted above, acquiring slope angle measurements posed a challenge when measuring by hand, but excessive slope steepness is a serious issue where ADA compliance is concerned. Both scan methods successfully generated slope measurements. Structure Sensor measured the slope at 16.5 degrees, while the angle extracted from the P40 point cloud was 17.5 degrees. As observed from field measurements, the ramp in question was of excessive steepness. (The ADA specifies maximum acceptable slope angle of 10%.) While the team did not deploy high-accuracy surveying techniques necessary to reality-check the slope measurements with complete accuracy, the scan output was judged highly encouraging for generating easily extracted and robust slope measurements.