Drop-down
Activating the Lidar Module, will add the Lidar Toolbar as 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. See Toolbars Sub-Menu for more information on enabling toolbars and customization.
On the toolbar are options to change the draw or color mode, quickly classify or re-classify selected points, and
auto-classify Lidar points.
Selecting the Color or Draw ModeFor 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/Elev — Colors the Lidar points
by Red, Green, Blue (RGB) values if present, otherwise will use the elevation
values.
Color Lidar by Elevation— Applies
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.
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 Ground— The 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. When there are no points classified in a surface class, such as ground, this height above ground calculation is not exact. The
process may take a few moments to calculate the first time, as ground
height is determined for each individual point.
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. If there is no pattern to the point index display colors, and this display mode shows a noisy mix of colors, the point cloud is not ordered in a way that is spatially organized, and that can impact display and processing times. See the Global Mapper Package export or Selected Layers Context Menu for options to reorder points spatially.
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 non-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 single 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.
The automatic classification options available on the toolbar are:
Can be used to automatically classify Noise points based on user-defined parameters.
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.
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 building polygons, tree points or polygon and/ or powerlines from classified Lidar data.
Convert the selected lidar points into a 3D mesh surface.
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 so the points match the control elevations.
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.
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.
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 Selected Lidar Points – Ground
Classify Selected Lidar Points – Vegetation Low
Classify Selected Lidar Points – Vegetation Medium
Classify Selected Lidar Points – Vegetation High
Classify Selected Lidar Points – Building
Classify Selected Lidar Points – Wire (Conductor)
Classify Selected Lidar Points – Water
Classify Selected Lidar Points – High Noise
Classify Selected Lidar Points – Model Key-point