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Cloud Check (LAS / LAZ doctor)

Before a cloud becomes a surface: what the file says about its units, zone and datum vs what the drawing says - every mismatch named, with its fix.

Command VDCCLOUDCHECK · every VDC tab › Full Suite panel
Before a cloud becomes a surface: what the file says about its units, zone and datum vs what the drawing says - every mismatch named, with its fix.
LAS / LAZ header + VLRs (+ every point) → compare with the drawing's units, zone and extents → OK / Warn / Fail + fix The file says LAS 1.4, format 6, 48 M points WKT: NAD83 / SC (ft) EPSG 2273 Vertical: NAVD88 height (m) Classes: 2 ground 61%, 5 veg 22% Density 14 pts / sq ft The drawing says Zone SC83F (US survey foot) Units: feet Extents: the site linework Report grid FAIL intl ft vs US ft: 5.2 ft shift FAIL mixed XY ft / Z m WARN too sparse for curbs OK classes, extents each row carries its fix; text + CSV in VDC Reports Reads the LAS / LAZ file, never the attached cloud. No datum shift, no geoid - it flags them, it does not fix them.

What it does

  • Reads: version, format, count, scale, WKT or GeoTIFF CRS, H + V units and datum, returns; with Read every point the class histogram, density (over the occupied site) and true extents.
  • Compares: units (metres vs feet, US survey vs international foot with the shift it causes), mixed XY / Z units, zone, local coordinates near 0,0, extents vs the drawing.
  • Reports: OK / Info / Warn / Fail grid with a fix per row; text + CSV in VDC Reports; Full intake adds the check-shot QC.

Watch for

  • Assign the drawing's coordinate system first - "Feet" alone does not say which foot.
  • A file with no CRS is judged from its numbers only.
  • Density and shift thresholds are your office's numbers, not a standard.

Dialog

Cloud Check (LAS / LAZ doctor) dialog
Cloud Check (LAS / LAZ doctor) - VDCCLOUDCHECK
Cloud Check (LAS / LAZ doctor) dialog
Cloud Check (LAS / LAZ doctor) - VDCCLOUDCHECK
Settings file: %APPDATA%\VDC\CloudCheck\settings.json

When to use it

  • A drone, lidar or scanning vendor delivers a LAS / LAZ - check it before it goes anywhere near a surface.
  • A cloud imported into Civil 3D lands miles away, the wrong size or upside-down in elevation.
  • You need to tell a vendor, in writing, exactly what is wrong with a delivery.
  • Full intake: check the file and test it against the crew's check shots in one report.

How to run it

  1. Run VDCCLOUDCHECK; Add files... (several at once is fine); choose Check the files or Full intake.
  2. Leave Read every point on for classes, density and true extents (off = header only, instant).
  3. Set the thresholds to your office's practice if the defaults do not fit; OK.
  4. Read the report grid - Fail rows first, each with its fix; Open the report for the text copy in VDC Reports.
  5. Full intake: the QC dialog opens next with the first file as the tested cloud - pick the check shots.

Options

  • Mode: Check the files, or Full intake (check + check-shot QC in one combined report).
  • Read every point: on = class histogram, density and true extents; off = header and coordinate-system records only.
  • Stop after: the per-file point cap (60 M by default, 0 = all).
  • Coordinate shift that fails: 0.10 drawing units - below it a foot mix-up is a warning, above it a failure.
  • Density for curbs / for a surface: 10 and 0.5 pts per sq ft by default - starting points, not standards.
  • Local-coordinate limit: both X and Y under 50,000 = an assumed / local system that needs a calibration.

Watch out for

  • A file with no coordinate system is checked from its numbers only - the zone and foot cannot be confirmed; get the CRS in writing.
  • The drawing must have its coordinate system assigned for the zone and foot checks; INSUNITS 'Feet' does not say which foot.
  • US survey vs international foot is 2 parts per million - invisible on a small site, several feet at State Plane coordinates. Never fix it by scaling by hand.
  • Density is measured over the occupied part of the site; a good average can still hide sparse stretches - read the 'sparsest tenth' figure.
  • The check reports what the file and the drawing say. It does not prove either is right - a wrong CRS record in the file looks right here.

Related: Cloud QC (Cloud / Surface vs Check Shots) · Ground Thin (Lidar to Ground Shots) · Cloud Slice (Point-Cloud Slabs to Linework)