Unroll

Menu

This tool is accessible via the 'Tools > Projection > Unroll' menu.

Description

This method 'unrolls' a point cloud from a cylindrical (or conical) shape onto a plane:

Cylindrical shape to unroll

Cylindrical shape unrolled

Unrolled cone

Procedure

Select a single cloud then start this tool.

Cylinder

'Unroll cylinder' dialog

To unroll a cylindrical shape, the parameters are:

• axis of revolution (X, Y or Z)
• cylinder radius
• optionally a point on the axis (otherwise CloudCompare can try to guess it by computing the gravity center of the point cloud)
• since version 2.11, it is also possible to specify the angular range. By default it's [0-360], but you can input any angular value, and even multiple revolutions.

'Unroll angular zero and sign' dialog

Cone

Since version 2.9, this method unrolls a cone in a way that preserves surfaces (as if the cone was 'rolling' on a planar surface).

'Unroll cone' dialog

To unroll a conical shape, the parameters are:

• axis of revolution (X, Y or Z)
• half angle (this is the aperture angle at the cone apex) in degrees
• the cone apex position in 3D

Straightened cone

This mode was corresponding to the 'Cone' unrolling mode in version 2.8 and prior.

This method unrolls a cone-shaped cloud as if it was a cylinder, by first 'straightening' the cone walls.

'Unroll straightened cone' dialog

To unroll a straightened conical shape, the parameters are:

• axis of revolution (X, Y or Z)
• half angle (this is the aperture angle at the cone apex - in degrees)
• the cone apex position
• the base radius of the 'straightened' cone (= cylinder)

Export deviation scalar field

A checkbox named 'Export deviation scalar field' allows to compute for each point its radial distance to the theoretical unrolling shape (cylinder or cone). A new scalar field will be added to the output cloud.