Lidar Module Overview

Global Mapper's Lidar Module is an optional add-on to the software that provides several advanced Lidar processing and analysis tools, many of these tools can be leveraged through the Lidar toolbar, though additional options will be added to Lidar Load Options, Lidar Export support, and will propagate to other menus that will enhance the handling of Lidar data within the Global Mapper application. If you are interested in evaluating this Module you can request an evaluation license for it under the Help menu, to purchase this Module visit the purchase page on our website.  

Some of the Lidar enhancement features include (but are not limited to):

The Lidar Toolbars

Activating the Lidar Module, will add theLidar Toolbaras an additional component to the Global Mapper User Interface. Like other Global Mapper toolbars, this interface component may be activated and deactivated in the View > Toolbars menu.

On the toolbar are options to change the draw or color mode, quickly classify or re-classify selected points, and auto-classify Lidar points.



Lidar (Manual Classification)

Selecting the Color or Draw Mode

For changing the draw or color mode for displayed lidar points, the Lidar Toolbar features a drop down menu that allows users to easily select the display characteristics of the point cloud. Draw/color options on the dropdown menu include:

Color Lidar by RGB/ElevColors the Lidar points by Red, Green, Blue (RGB) values if present, otherwise will use the elevation values.

Color Lidar by ElevationApplies a color spread to the range of elevations found in the Lidar data.

Color Lidar by Intensity — Color lidar points from black to white by the intensity of the return pulse. Lidar classified with this method can sometimes be used in place of aerial imagery. Most topographic lidar systems record the intensity of the return pulse, measuring the strength of the return. The number of returns will be determined by the composition of the surface object reflecting the return.

The Intensity values can be used to create an image, and are commonly used for identifying and classifying different ground features and can be used as a substitute for aerial imagery.

Color Lidar by Classification Colors Lidar points by the ASPRS defined classification values. Customize the colors from the Filter Lidar Data tool.

Color Lidar by Return Number — Applies a color spread to the range of return values, which typically range from 1 to 5.

Color Lidar by Height Above GroundThe ground height is calculated from the Lidar point cloud, either from the surface group of Lidar classes (Ground, Road and Water) or by the minimum elevation in large chunks. This is not exact and the process may take a few moments to calculate the first time, as ground height is determined.   

Color Lidar by Point Source ID — This value will indicate the file from which the point originated, valid values are between 1 and 65,535. Allows for flight paths for Lidar data collection to be visualized.

Color Lidar by Point Index— This will color the points in 512 point chunks with the same color, allowing visualization of how the points are stored spatially in the file. This is useful for things like improving compression by visualizing the spatial arrangement and testing re-arrangement to get better compression.

Color Lidar by Return Height Delta —This will color points by the difference in elevation between the first and last return of a multiple return. This will be the height in meters between the elevation of the first return and last return. For example, for a tree where the first return was near the top of the tree and the last return off the ground, it could be the height of the tree.

Color Lidar as CIR (Color Infrared)— This will color points with the band layout NIR/Red/Green. This is how 4-band infrared data is commonly visualized. The vegetated areas tend to be red.

Color Lidar using NDVI (Vegetation) Colors points using the calculated NDVI value (computed from NIR and Red bands) using Global Mapper's built-in NDVI shader. Vegetated areas will be green and not vegetated areas will be a shade of blue.

Color Lidar using NDWI (Water) — Colors points using the calculated NDWI (Normalized Difference Water Index) value (computed from the NIR and Green bands) using the new built-in NDWI shader. Water areas (NDWI > 0) will be blue and non-water will be white/gray.

Color Lidar by Point Density —Color points using calculated point density. The point density is calculated based on the full point cloud loaded in the layer. To visualize the point density for a particular classification, the subset of points must be loaded or copied to new layer.

Color Lidar by Withheld Flag — Points flagged as withheld will appear red. All other points will appear blue.

Color Lidar by Key Point Flag — Points flagged as Key Points will appear red. All other points will appear blue.

Color Lidar by Overlap Flag — Points flagged as Overlap points will appear red. All other points will appear blue.

Automatic Classification

The automatic classification options available on the toolbar are:

Auto-Classify Noise Points

Can be used to automatically classify Noise points based on user-defined parameters.

Auto-Classify Ground Points

Specify the minimum height in meters (above the local average) that a point has to be in order to be considered a non-ground point.

Auto-Classify Non-Ground Points

Specify point spacing and threshold values such as Minimum Height, Vegetation Distance and Maximum Co-Planar Distance to automatically classify non ground point features.

Extract Vector Features

Set up Building Extraction Settings for use in a specified resolution for extracting 3D Building outlines from Lidar point cloud data.

Additional Tools

Lidar QA - Compare/ Adjust Elevations to Control Points

Control points may be compared to nearby Lidar points. This tool reports the differences and RMSE between the control points and nearby LiDAR points. It can also be used to adjust the point cloud to

Filter Lidar Data

Allows the user to filter out Lidar points by Classification. Also allows for changing the color or classification groups of Lidar classes. See more information on changing the Class properties. Additional Advanced Filtering tools can be applied while running an auto-classification, or by selecting Lidar Points with the digitizer tool.

Apply Color to Lidar Points

Applies color values from loaded imagery to Lidar points based on X, Y location values. Color values can include R,G,B values from true color imagery, or values from multi-band imagery or raster calculations for LAS versions 1.4.

Manually Classifying Points

The Lidar Module also allows the user to manually classify or re-classify selected Lidar points. To utilize the classification buttons found on the Lidar Toolbar, select a group of lidar points with the Digitizer Tool and click the button corresponding to the classification you wish to use.

The manual classification options available on the toolbar are:

Classify – Ground

Classify Selected Lidar Points – Ground

Classify – Vegetation Low

Classify Selected Lidar Points – Vegetation Low

Classify – Vegetation Medium

Classify Selected Lidar Points – Vegetation Medium

Classify – Vegetation High

Classify Selected Lidar Points – Vegetation High

Classify – Building

Classify Selected Lidar Points – Building

Classify – Wire (Conductor)

Classify Selected Lidar Points – Wire (Conductor)

Classify – Water

Classify Selected Lidar Points – Water

Classify – High Noise

Classify Selected Lidar Points – High Noise

Classify – Model Key-point

Classify Selected Lidar Points – Model Key-point

Lidar Class Properties

To change the Class Properties of Lidar Classes, open the Filter Lidar Data window and right-click on an existing classification. This is also available in the Lidar section of the Configuration dialog.

Set Class Name... will allow you to customize the Lidar Class names. (If you export to LAS/LAZ files, the custom names that you selected will also be stored in those formats as they support custom classification schemas.)

Choose the option to set Set Class Color... to change the colors when using Color Lidar by Classification

Set Class Group(s)... will open the Select Lidar Groups window.

Each Lidar Class can be added to a number of groups that are used for Lidar Automatic Extraction and Lidar statistics like Height Above Ground. These are configured by default to coordinate with the ASPRS classification definitions, but can be customized for other classification schemes.

  1. Surface - any returns that can be considered surface, like ground, water, road, etc. This group is used in determining Height Above Ground.
  2. Off-Surface - any returns that definitely aren't on the surface (i.e. powerlines, bridge, noise)
  3. Noise - which points are noise classes to be ignored for most things
  4. Powerlines - which classes are powerlines. This group is used in Automatic Feature Extraction of Powerlines.
  5. Structure - which classes are structures, like buildings
  6. Vegetation - which classes are vegetation
  7. Bathymetric - which classes are below the water surface

Advanced Filtering Options

The advanced filtering of Lidar Data can be applied from the Digitizer tool, or when using the Lidar Toolbars Automatic Classification and Feature Extraction tools.

To access this option from the Digitizer, select a set of Lidar Points, then right-click with the digitizer and under Advanced Selection options choose the option to Filter Selected Lidar Points By Elev/Color/Class etc...

For more information about advanced filtering of Lidar data, see Filter Selected Lidar Points

Lidar Module: Additional Functionality

The addition of the Lidar Module adds Lidar functionality to the Path Profile/LOS and Create Elevation Grid commands. The Lidar Module also enables Custom Feature extraction from the Path Profile view.

Lidar classification colors can be changed and customized in the Lidar section found in the Configuration.

Specialized Lidar import options will be included in Lidar Load Options that allow for quicker import, and additional filtering options.

Additional Export Options for the Lidar LAS format.