Overview

High-quality control is the foundation of accurate Dusty layout. Whether your project uses surveyed floor points, wall-mounted drift nests, offset lines, manual offsets, or point-cloud–derived points, the way you record control points in the field directly affects stationing accuracy.

This guide walks you through the best practices for capturing reliable control points, with recommendations customized to each control workflow used in industry. The goal is simple: help you station confidently and avoid layout shifts, drift, and restationing inconsistencies.

Note that layout accuracy improves significantly with more accurate and more numerous control points.

Best Practices for All Control Methods

Use at Least 6–8 Control Points per Station

Three points are the minimum, but using only three lets one bad point distort the entire station.
More points = more stable best-fit alignment.

Ensure Every Point Is Physically Intact

Before scanning:

• Clean the point
• Ensure it hasn’t been scratched or covered
• Confirm nobody has moved or damaged the marking

Spread Points Across Your Work Area

Avoid clusters. Choose a wide footprint to improve solution stability.

Check Differences/Error Values as You Scan

If one point is much higher than the others:

• Deselect it
• Rescan the point
• Choose an alternate point if differences or error values remain high

Keep the Tracker Stable

• Tripod must be tight and level
• Avoid vibrations from nearby equipment
• Don’t record points if the floor is shaking

Scan Across Full Stationing Area

Record control points that clearly define the full stationing area, not just one side of it.

Surveyed Control Points (On the Floor)

This is the most common way of setting control with Dusty. It requires surveyed CPs marked on the slab and provided in a CSV.

How to Identify Good Surveyed Floor Points

Look for:

• Crisp “X” or target mark
• Legible labeling that matches the CSV
• A location consistent with the survey map

Best Practices

1. Clear dust, mud, and markings before scanning.
2. Verify label names on the slab match the control list.
3. Avoid points near slab cracks, spalls, or unfinished areas.
4. If errors are consistently high, check whether the point may have been mis-surveyed.

When to Flag a Survey Issue

Surveyed floor CPs can sometimes include placement errors—bi-pod workflow tolerance can reach ⅛″–¾″ depending on technique. If multiple points are off, contact your surveyor for verification.

Surveyed Wall/Column Control (Drift Nests)

This is a high-accuracy method used with RTS or laser tracker workflows.

How to Identify Good Drift Nests

• Permanently mounted to columns/walls
• Clean and rigidly attached
• Not loose or spinning
• Reflector seats flush and stable

Best Practices

1. Insert the reflector carefully—avoid wiggling or bumping the nest.
2. Confirm the nest hasn’t moved since installation.
3. Check for construction activity that may have vibrated or hit the mount.
4. Use as many wall nests as practical—this method produces extremely stable control.

Note

This is one of the most accurate forms of control and typically gives the strongest station-to-station consistency.

Surveyed Offset Lines (Grid Offsets)

Common on legacy projects where contractors use axis lines snapped from a Robotic Total Station (RTS).

How to Recognize Offset-Line Control

• Chalked grid lines snapped on slab
• Crossed lines forming intersection points
• Often used in lieu of surveyed point CSV

Best Practices

1. Verify offset distances match the survey plan.
2. Re-snap lines if they are faint or disturbed.
3. Create control points in the Dusty App at line intersections.
4. Scan at least three intersections that form a wide triangle.
5. Avoid intersections near slab edges or curled concrete.

Watch Out For

Human error in snapping lines or tape-measuring offsets can introduce moderate accuracy issues. Problems here often show up after restationing.

Manual Offsets (Columns, Gridlines, Slab Corners)

Used when no surveyed control is provided.

Examples of Manual Offset Targets

• Offsets from column centerlines
• Offsets from stair openings or slab corners
• Tape-measured orthogonal grids

Best Practices

1. Use long tape pulls for better accuracy.
2. Double-check squared conditions (use 3-4-5 or diagonal checks).
3. Mark the intersection points clearly and record them into the App.
4. Use more points than usual—manual control has greater risk of error.
5. Ensure operator consensus: measure, check, and confirm before locking points in.

Limitations

Manual offsets create weaker global control networks. They should be used only when necessary and with extra redundancy.