Smart Scan in Carlson Scan

A horizontal scan is built from a stack of full 360° sweeps, one at each pitch angle. Smart Scan spaces those sweeps further apart toward the two ends of the probe, where each sweep only traces a small circle, and keeps full density perpendicular to the probe. With the probe vertical, the usual setup, that means fewer sweeps near straight up and straight down and full density around the horizon. The result is more even point coverage in fewer sweeps.

The Crowding Problem

Every ring is a full turn of the head, but the rings are not the same size. The ring at 90°, perpendicular to the probe, traces the widest circle around the cavity. A ring 10° from the probe axis traces a circle only about a sixth as wide, because ring size follows sin(pitch). Each sweep still records points around its whole turn, so the points on small rings near the poles land close together.

Each sweep records points around its whole turn. With the probe vertical, the ring at 90° circles the cavity walls, while the ring at 10° is about a sixth as wide, so the same number of points crowds into a small circle near the roof. Diagram: NDEVR.

With an even pitch step, the scan spends as much time on each tiny polar ring as on the full-width ring at 90°. With the probe vertical, those polar rings add many points to the roof and floor directly above and below the scanner, while the walls get no extra coverage.

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Why the poles, not the walls

With the probe vertical, the walls around the horizon carry the shape you care about in most cavities and stopes. The roof and floor directly above and below the scanner are already covered by every nearby sweep. Thinning the polar rings removes repeat coverage, not new surface.

The Smart Scan Rule

Smart Scan keeps the pitch step and adds an extra gap after each sweep. The gap depends on how close that sweep is to the probe axis:

next pitch = pitch + step + |cos(pitch)| × Smart Scan Angle

|cos(pitch)| is 1 along the probe axis (0° and 180°) and 0 perpendicular to it (90°). So the full Smart Scan Angle is added near the poles, part of it in between, and nothing at 90°. With the probe vertical, the poles are straight up and down and 90° is the horizon.

Spacing between sweeps with a 3° pitch step and the default 3.5° Smart Scan Angle. Directions assume a vertical probe.
Pitch	\|cos(pitch)\|	Normal spacing	Smart Scan spacing
0° or 180° (along the probe; straight up or down)	1.00	3°	6.5°
45° or 135°	0.71	3°	5.5°
60° or 120°	0.50	3°	4.75°
90° (perpendicular to the probe; horizon)	0.00	3°	3°

Interactive Comparison

Each ring below is one 360° sweep, drawn with the probe vertical. The left sphere uses an even pitch step. The right sphere adds the Smart Scan gap. Move the sliders to match your scan settings, then press Play scan: both scanners run at one sweep per tick, so you can see Smart Scan finish first.

Pitch step 3°Smart Scan Angle 3.5°

Near poles (0°/180°)

At 45°/135°

At 90° (horizon)

Fewer sweeps

The rings follow the same spacing rule Carlson Scan uses to plan a horizontal scan, over a full 0°–180° pitch range, with the probe vertical. A horizontal probe gives the same pattern turned on its side. Set the Smart Scan Angle to 0° and both spheres match. Diagram: NDEVR.

A scan with narrower vertical limits keeps only the rings inside them. Because the extra gaps sit near the poles, a scan limited to a band around 90° saves fewer sweeps than the full sphere shows.

Settings

Both controls are in the Carlson Scan settings dialog, under the default scan settings:

Smart Scan

Turns the extra polar spacing on or off for new horizontal scans. On by default.

Smart Scan Angle

The extra gap added at the poles, along the probe axis. Default 3.5°. Larger values thin the polar rings further.