Align to Control (ATC) ties a capture to ground control surveyed in the field. You match known control points to the same features in the point cloud, Looq fits the alignment and reports how well it fits, and the capture is reprocessed in your control's coordinates.
Before you start
• A completed capture. Align works on one capture at a time.
• Control coordinates in the site's coordinate system. The import panel shows the site's CRS and units (for example NAD83(CSRS) / UTM 12N · EPSG:2956 · m), so check your file uses the same.
• At least 3 control points you can see in the capture. More points, spread across the capture, give a better fit. Spare points make good check shots.
Control points and check shots. Control points drive the alignment. Check shots are held out of the solve and only used to measure how well it fits. You need at least 3 control points; check shots are optional but recommended.
Opening Align
Open a site and choose Align in the left panel. Pick the target capture at the top of the panel — every point you add is tied to that capture. If nothing is selected, the button tells you to select a capture first.
The Align panel on a capture that hasn't been aligned: the ATC Wizard button, and the three steps of the manual route.
Switching captures discards unsaved work. Changing the target capture throws away unsaved control-point work on the current one. Looq asks before it switches.
There are two routes to the same result:
• Start ATC Wizard — walks you through adding points, matching them and running the alignment, one step at a time.
• The manual tools along the top of the panel — Import control points, Add control point, Edit selected, Delete selected and Align Capture — for when you'd rather work the table yourself.
Step 1 — Add your control points
Import from a CSV
1. Press Import control points.
2. Choose your .csv file (CSV is the only supported format). Turn on Include headers if the first row holds column names.
3. Map the columns: tell Looq which column is Name, Easting, Northing, Elevation and, optionally, Description. Use Search columns... on wide files, and Reset Columns to start the mapping again.
4. Tick the rows you want — Select all rows takes everything — then press Import.
If nothing imports, the message reads “No valid rows. Map Easting/Northing/Elevation to numeric columns.” That almost always means a column is mapped to the wrong field, or a header row is being read as data.
Add or edit points by hand
Add control point opens a short form: Name, Code and Type (Control Point or Check Shot). Edit selected works on exactly one selected point; Delete selected removes one or more.
The control-point table
Every point is listed with its type (control or check), name and code, with the site's units in the column headers. Imported points start ticked.
Only ticked points are used. Ticked rows go into the alignment; unticked rows are left untouched on the capture. Points missing either a control coordinate or a matched model point are skipped rather than blocking the run.
Step 2 — Match each point to the model
For each control point, find the same ground feature in the point cloud and click it. In the wizard, press Start matching model points and work through the points one at a time:
• Select — puts the viewer into picking mode (Picking…). Click the feature in the cloud and the point shows as Selected.
• Reset — clears that pick so you can try again.
• Previous point — steps back to fix an earlier match.
• Set each point as a Control Point or Check Shot as you go.
You don't have to match every point. Leave any you can't see in the capture — they're skipped.
Pick the exact feature. Click precisely what the surveyor shot — a nail, a paint mark, a corner — not something near it. A few centimetres of loose picking shows up directly in the RMS error.
Step 3 — Review and run
The review step shows the RMS Error (root mean square) for the fit, calculated from exactly the points you've confirmed. You can still switch points between control and check here and the figure updates straight away — take a doubtful point out of the solve and see whether the error drops.
Note: Run Alignment will perform a rigid-body transformation (shift, rotation, and scale). Non-rigid transformations will be supported soon!
When the fit is acceptable, press Run Alignment. Looq will only run when:
• at least 3 control points have a matched model point;
• the points are spread across the capture — clustered or near-straight-line points can't produce a reliable alignment, and Looq will ask you to check they're well distributed;
• the capture isn't already processing.
Running reprocesses the capture. Alignment runs as processing on the capture. The Align panel is locked while it runs, and the capture shows as in progress until it finishes.
After alignment
Action |
What it does |
|---|---|
Download ATC report |
A PDF report of the alignment. Available once alignment has completed. |
Download projected coordinates |
A CSV with, for every point: Model Id, Model Easting / Northing / Elevation, Control Id, Control Easting / Northing / Elevation, Residual Error and Code — in the site's units, to 3 decimal places. |
Revert to original |
Undoes the alignment and restores the capture to its original position. Only available on an aligned capture that isn't processing. |
Run again |
Re-run the alignment on an aligned capture. Its control points load automatically, so there's nothing to re-import. |
If the existing alignment can't be read. Occasionally Looq can't determine the alignment already applied to a capture. Running again is blocked until you press Revert to original and align from scratch.
When Align is unavailable
What you see |
What to do |
|---|---|
“This scan is currently processing. Alignment actions are disabled until it finishes.” |
Wait for processing to finish, then return to Align. |
“Failed to load control points for this scan.” |
Press Retry before importing or aligning. |
“Import or add control points first” |
Add points — see Step 1. |
“Select at least 3 control points to align” |
Tick more rows, or add more control points. |
“The applied alignment for this scan could not be determined.” |
Press Revert to original, then align again. |
Why it matters downstream
Your Looq capture will not be aligned to your survey ground control until this process has been run. Any production work that is performed in qSurvey or qPole will not be aligned along with the point cloud data, and will have to be redone.
Coming Soon!
Non-Rigid Align to Control
A full reprocessing of the capture to redo the bundle adjustment and fit the capture onto your ground control.
