Overview

Distance error is the difference between where a point or line is supposed to be in the model and where it is placed in the field. In construction layout, even small distance errors can compound across a project and lead to misalignment, rework, and schedule impacts.

Distance error is most commonly introduced during control setup, stationing, or measurement. Understanding where it comes from and how to identify it early is critical to maintaining layout accuracy.

Note: When a control point is deselected, it's expected that the control point appears in the Distance Error table.

What You’ll See in the Field

• High delta values during stationing or control point recording
• Lines not aligning with physical features like columns or walls
• Inconsistent measurements between printed layout and tape checks
• Layout shifting between different station setups
• Verification point failures or repeated station verification issues

Why This Happens

• Control point inaccuracies Small survey errors or misplaced control points distort the layout
• Too few control points Using only the minimum number (3) increases sensitivity to error
• Bad control point included One incorrect point can pull the entire layout off during best-fit alignment
• Survey tolerances Real-world surveying introduces error due to equipment, visibility, and setup conditions
• Environmental factors Vibration, movement of the tripod, or poor line of sight can affect measurement accuracy
• Coordinate or scaling issues Mismatched units or coordinate systems in the file can introduce distance discrepancies

How to Troubleshoot Distance Error

1. Check delta and error values
   • Review station information in the Dusty App
   • Identify any control points with unusually high error
2. Remove suspicious control points
   • Re-station without the outlier point
   • Compare results to see if error improves
3. Increase control point count
   • Capture additional control points (aim for 5–8 when possible)
   • More points reduce the impact of any single bad point
4. Verify control point placement
   • Confirm points are clearly marked and not disturbed
   • Re-shoot or re-measure if needed
5. Check station setup conditions
   • Ensure tripod is stable and level
   • Avoid areas with vibration or heavy traffic
6. Validate file inputs
   • Confirm units, scale, and coordinate system are correct
   • Re-export control or layout files if needed
7. Re-run station verification
   • Use a verification reflector to confirm alignment before printing

Best Practices

• Use more than 3 control points Minimum is not recommended—more points improve accuracy
• Distribute control points evenly Avoid clustering in one area of the floor
• Avoid known bad points Do not include points that look damaged or questionable
• Set up in stable areas Keep the total station away from vibration and movement
• Verify before printing Always confirm acceptable error before starting layout
• Align teams on control strategy Ensure survey, VDC, and field teams are using the same control network