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RayColour

RayColour is a tool for coloring and shading ray clouds using various methods. It can apply colors based on different attributes like time, height, geometry, normals, intensity, or from external images.

Usage

The general syntax for using RayColour is:

raycolour <input_file> <coloring_method> [options]
  • <input_file>: The ray cloud file to be colored.
  • <coloring_method>: The method to use for coloring (see options below).
  • [options]: Additional options to modify the coloring process.

Coloring Methods

Color by Time

raycolour raycloud.ply time

Colors rays based on their timestamp, cycling through a spectrum with a 60-second period for quick scan length assessment.

Color by Height

raycolour raycloud.ply height

Colors rays based on their Z-coordinate (height) using a spectrum with 10-meter wavelength.

Color by Geometry Shape

raycolour raycloud.ply shape

Colors based on local geometry characteristics:

  • Red: Sphericity (spherical structures)
  • Green: Cylindricality (cylindrical structures like tree trunks)
  • Blue: Planarity (planar structures like walls)

Color by Surface Normal

raycolour raycloud.ply normal

Colors rays based on their surface normal direction.

Color by Alpha Channel (Intensity)

raycolour raycloud.ply alpha

Colors based on the alpha channel, which typically represents intensity values.

Set Alpha Channel Only

raycolour raycloud.ply alpha 1

Sets only the alpha channel, where zero represents unbounded rays.

Set RGB Color

raycolour raycloud.ply 1,0,0

Sets a flat color using RGB values (0.0-1.0 range). Example above sets red color.

Color for Branch Analysis

raycolour raycloud.ply branches

Specialized coloring for vegetation analysis:

  • Red: LiDAR intensity
  • Green: Cylindricality
  • Both values are typically higher for branches than leaves.

Color from Image

raycolour raycloud.ply image planview.png

Colors all points using a horizontal image projection, stretched to fit the point cloud bounds. Useful for applying aerial/satellite imagery to point clouds.

Options

  • --lit or -l: Applies shading effects to the colored cloud. Note: This is slow on large datasets.

Output

The tool generates a colored ray cloud with the suffix _coloured.ply.

Examples

Color by time with shading:

raycolour forest_scan.ply time --lit

Apply geometry-based coloring:

raycolour building_scan.ply shape

Apply satellite image coloring:

raycolour terrain_scan.ply image satellite.png

Set uniform red color:

raycolour scan.ply 1,0,0

Color for vegetation branch analysis:

raycolour forest_scan.ply branches

Additional Information

  • The tool supports various geometric calculations for shape-based coloring including sphericity, cylindricality, and planarity.
  • Image coloring automatically stretches the image to match the point cloud bounds and warns if aspect ratios don't match.
  • For more detailed information on command usage and implementation details, refer to the RayColour source code at raycloudtools/raycolour/raycolour.cpp.