VTube-LASER Spike Filter

Laser stripes from the FARO are composed of a string of points in space. When scanning a diameter, VTube expects a natural arc to occur as the scan line wraps around the diameter. If any point departs too far from this path, then the filter automatically removes outlier vertex spikes in cylindrical laser stripes. An outlier is detected when the angle between any three adjacent points exceeds a user-entered value. The default value is from 15 to 30 degrees.

Laser Stripes On Cylindrical Tube Shapes

On a tube, FARO scanner stripes form a polyline with a maximum curve. No matter which way the operator positions the scanner on the tube, the angles between these points should never climb above a certain value. The only case where this isn't true on a cylinder is if the cylinder contains deformations like pits and raised bumps.

Handling High Reflectivity Spikes

The other situation where the laser scanner might see spikes is when measuring highly reflective tube. The points returned from the tube surfaces that come from highly reflective regions of the diameter may then be registered as spiking away from the diameter. This filter recognizes that possibility and removed any data that spikes away from the curve before it is given to the math engine. The internal FARO filter, if enabled, first detects spikes using its own algorithm. Any spikes that make it past that filter can then be removed by the VTube-LASER spike filter. This greatly increases the reliability of the data being sent back from the scanner.

When to Increase the Spike Filter Angle

Doing what is described here is very unusual - but giving the example will help demonstrate how the spike filter works. If you are measuring a very small diameter, and/or have the maximum point per stripe set very low, then you will want to increase the spike filter angle value. For example, if you chose to cull the point count down to three points per stripe, then the angle between the 3 points on the diameter will almost always exceed 15 degrees. The angle would need to be increased to 80 or 90 degrees to measure the tube using this configuration.

Other

• Back to VTube-LASER
• Back to VTube Software Updates (for LASER Mode)
• See VTube-LASER Customer Support Page to download the latest version.
• Back to VTube-STEP
• Back to VTube-STEP Revisions
• See also How to Diagnose Inaccurate VTube-LASER Measurements