Splays and LRUD

When a scan stops, SpeleoMap measures the passage from the scan itself. From the scan's start and end stations it reads left, right, up and down out to 10 m, plus extra wall shots. A wall out of range stays blank, never zero. See Take a Scan.

Left, right, up and down are always saved. The Splays setting adds more: Off, Standard (4), Plan (8), Sections (16: every 45° in plan, cross-section and profile) or Detailed (24). None point straight along the line forward or back: the Cave Line is the leg. Set it in Scanning settings.

Pick Splay from the Drop Station menu. A station drops and the camera opens as a rangefinder: aim and tap Shot (or press volume up) for each wall shot, then close the camera. With the phone's LiDAR, shots reach about 5 m. A shot is refused when the ring is red (no reading, or past about 5 m).

Pair a Bluetooth laser meter and tap Meter on: the meter gives the distance and the phone gives the direction. It reaches much farther and works on any iPhone. See Rangefinder and Laser Meter.

On each station's detail page, in the Cave Line 3D view (splay toggle), in Survex and Therion exports, and in the PDF station table. See Export Formats. In the scan viewer, Survey also has LRUD and a Splay burst (6, 12, 18 or 24) for a quick look; they aren't saved.

The Cave Line itself is the survey leg: the book's distance, azimuth (fore and back) and vertical angle all come from it. LRUD and splays give the passage around it. Foresight and backsight were a check; SpeleoMap's checks are snaps, loop closures and the drift monitor.