Point clouds and G-code

Point clouds as las laz e57 pcd, and a ply with no faces; a 3D printer's or a CNC (computer numerical control) machine's G-code as gcode gco g ngc

A scan opens as its points, and a print or a toolpath as its moves, drawn in 3D in the same view as a model. Drag to rotate, hold Shift to pan, use the wheel to zoom, and double-click to start over. Which format a file is, its bytes decide: a .las that is a well log's text is not taken for a scan.

Point clouds

Format	Files	Read
LAS, the survey and lidar file	las	versions 1.0 to 1.4, point formats 0 to 10
LAZ, LAS compressed by LASzip	laz	LAS 1.3 and before, and LAS 1.4's layered points
E57, the 3D imaging exchange	e57	every scan in the file
PCD, the Point Cloud Library's	pcd	ASCII, binary and compressed binary
PLY	ply	a PLY with no faces; one with faces opens as its triangles

The line above the view counts the points and gives the cloud's size. The list on the left of the toolbar colours them by what the file carries, its own colours first:

Choice	Each point coloured by
Colour	the colour it carries
Intensity	how strongly it returned the light: dark faint, white strong
Classification	its class: ground brown, vegetation green, building red, water blue
Height	how high it is, blue lowest to red highest; always offered

Box draws the bounding box, and Reset View goes back to where it opened.

A cloud of more than a million points draws about a million of them, evenly picked, and the line says how many it shows beside the count.

Points as a table

The table mode lists every point, a column a field, and SQL reads them all, not only the ones drawn:

SELECT classification, count(*), avg(z)
FROM 'survey.laz'
GROUP BY classification

A LAS or LAZ file is one table, its columns named as laspy names them: x y z, intensity, return_number, classification, gps_time, red green blue and the rest of its point format, and any extra bytes it declares. An E57 file has a table per scan, 'site.e57!/scan 0', and a PLY a table per element, 'mesh.ply!/vertex'. A PCD's fields keep their names.

A LAZ file of LASzip's first version, and a LAS version other than 1.0 to 1.4, say so by name.

G-code

A G-code file opens as what the machine will do: every move drawn as a line, layer by layer. A file that pushes filament is a 3D printer's, and its moves are extrusions, travels, retractions and primes; otherwise it is a CNC machine's, and its moves are cuts and rapids. Arcs are drawn as arcs, and the slicer comments of PrusaSlicer and Cura give the layers; without them, a new height a move makes something at starts a new layer.

Control	What it does
the colour list	Layer, blue the first to red the last, or Move Kind
Travel	moves that make nothing, on or off; Rapid for a machine, on at first
Box	the bounding box
the layer slider	the lowest and the highest layer shown — layers 0–139 of 139 · z 20.71 mm

Move Kind colours a print's extrusions orange, travels blue, retractions red and primes green, and a machine's cuts green and rapids grey.

The line above the view counts the layers and the moves, and for a print the filament it uses — 139 layers · 20,222 moves · 1,706.2 mm of filament.

The table mode is the moves, a row each: line, command, kind, layer, x y z, e, extruded, feedrate, length and tool:

SELECT kind, sum(length) FROM 'part.gcode' GROUP BY kind

A file with no G or M command in it is not G-code, and says so. A point cloud and a toolpath have nothing to measure.

Next: textures.