Overview
Choosing the right control points significantly impacts the accuracy of your layout. This article covers four key principles for selecting and recording control points to maximize stationing accuracy.
1. Record Widely Spread Control Points
Spread your control points as far apart as possible. They can be scanned in any shape or random arrangement — the key is that they cannot all fall on a single straight line.
⚠️ Do not record all control points in a straight line. This will degrade stationing accuracy.
2. Record Control Points Around Your Print Area
Position control points around the perimeter of your intended print area, not clustered inside it. This ensures adequate spacing relative to where the robot will be printing from that station.
3. More Recorded Points Is Always Better
The minimum is 3 control points, but recording more improves accuracy. For example, 4 control points with 1/8" error is better than 3 control points with the same 1/8" error.
More points give the system a larger dataset for a better "best fit" calculation when matching your scanned points to the digital files.
4. Large Control Point Spacing Is Better
Distance between a control point and the laser tracker matters as much as the error value itself. A control point 10' away with a 1/16" error may actually perform worse than a control point 100' away with a 1/8" error — especially if your print area extends out to 100'.
When evaluating your control points, prioritize those that are farther away and closer to the edges of your print area.
Quick Reference
| Principle | Worse | Better |
|---|---|---|
| Point distribution | All in a line | Spread wide in any shape |
| Placement relative to print area | Clustered inside print area | Surrounding the print area |
| Number of points | 3 points at 1/8" error | 4+ points at 1/8" error |
| Point distance | 10' away, 1/16" error | 100' away, 1/8" error |