User manual

FastSCAN 33

5.2.5 Apply Basic Surface:

When you have set the Basic Surface Processing values click on the Apply Basic

Surface button to generate the Basic Surface.

5.3 Registering the Sweeps

The various sweeps of the scan may not always overlap perfectly. This may be due

to:

• small errors in the scanner measurements

• metal objects interfering with the magnetic locater

• the object or reference moving unintentionally during scanning.

Such errors in sweep alignment are manifested as bumpy patches or blistering on the

Basic Surface. You can attempt to correct these by selecting Register Sweeps from

the Edit menu. The process is automatic and takes just a few seconds for a typical

scan. Once you have performed sweep registration, regenerate the Basic Surface in

the normal way and see if the RMS error has improved. Figure 23(a) shows an object

with artifacts before Register Sweeps has been used and 23(b) the improved result

after it has been applied.

Occasionally Register Sweeps can cause deterioration in the quality of the Basic Sur-

face. If the RMS error is larger after Register Sweeps has been applied, choose Un-

body transformation to each sweep, i.e. a translation and a rotation. Such transfor-

mations cannot correct misalignments due to problems that cause distortion of the

data within the sweep.

5.4 Surface Information

To view the statistics of your surface, open the Generate Surface dialog

box (Figure 19). For the raw data this shows the number of points, tri-

angles, sweeps and proﬁles. For the Basic and RBF Surfaces it shows the

number of points and triangles and the surface area.