Overview

When you station the FieldPrinter system, Dusty reports error values for each control point (CP). These values indicate how well each scanned point fits into the overall control network. High error values usually mean that one or more CPs are inaccurate, misplaced, or inconsistent with the rest of the network.

High error values are not a robot issue. They are an intentional warning system designed to surface control problems before layout begins.

What Error Values Represent

Error values describe:

• Deviation from expected position for each scanned control point
• Overall alignment quality based on the selected set of CPs

A single inaccurate CP can significantly distort the best-fit solution. Using more control points (6–8 recommended) reduces the influence of any one bad point and makes problems easier to identify.

Common Sources of High Error Values

Survey-related issues

• Instrument drift or calibration problems with total stations or trackers
• Debris or obstructions covering control point marks
• As-built features mistakenly used as survey references

Inconsistent jobsite control

• Control placed at different times by different crews
• Incorrectly snapped control lines or transposed offset measurements
• Manual offsets from columns or slab edges that are not truly orthogonal

File preparation problems

• Incorrect units or coordinate systems in the exported CSV
• Multiple control files uploaded over time, leading to outdated or duplicated CPs

How to Troubleshoot High Error Values

Scan additional control points

Three points are the minimum required to station, not the recommended number.

• Target 6–8 CPs per station whenever possible
• If adding more CPs lowers the overall error, the issue is likely a single bad point

Identify and remove the bad CP

Compare error values across all scanned points.

• Deselect the CP with significantly higher error than the rest
• Recompute the station
• Review error values again after recalculation

A single bad CP often introduces noticeable rotational distortion across the entire solution.

Physically inspect the control point

Walk to the suspect CP and verify:

• The mark is clean and unobstructed
• The location matches the original survey intent
• The tracker and tripod have clear line of sight
• No equipment or activity has moved or damaged the point since it was set

Confirm the survey workflow

If elevated errors persist:

• Ask the surveyor to re-shoot the CP
• Verify consistent coordinate baselines were used

Small survey errors can remain hidden until Dusty’s stationing process exposes them.

Recreate or reimport the control CSV

If the entire control network appears misaligned:

• Confirm units are correct (feet or inches, as intended)
• Remove outdated control layers from the Portal
• Republish the updated file to the iPad

Duplicate or stale control files can cause mismatches after new data is uploaded.

When to Stop and Re-Survey

Pause stationing and request survey verification if:

• More than half of CPs show elevated error values
• Error values swing significantly from one day to the next
• Multiple survey methods were mixed without a shared reference
• Control lines or columns appear shifted relative to each other

Global control problems cannot be corrected by adjusting Dusty stationing alone.

Field Practices That Reduce CP Errors

• Place CPs in low-traffic areas to reduce disturbance
• Request wall or column control when long-term accuracy is required
• Use a single, shared control workflow across all trades
• Re-shoot control points when layout expands into new areas