May 12, 2021

GeoTalks Express What’s New with Lidar in 22.1? Questions and Answers

Thank you for attending the GeoTalks Express webinar, What’s New in Global Mapper v22.1. Registered attendees for this webinar should have received an email granting access to the recorded presentation posted on our YouTube channel.

​Will the classification tool work with non-lidar data such as bathymetry?

The classification tools should run with bathymetric data that is brought in like lidar as a point cloud. The ground classification tool will likely run the best along with the noise identification tool. The non-ground classification, for buildings and vegetation, can be used on any point cloud but is not applicable for bathymetric data.

Do you have a certain set of standard parameters for automatic point cloud classifications?

The automated classification tools do have some default values populating the parameters, but for better classification results from these tools you should alter the parameters based on your dataset. 

Is it [classification] possible for power line poles?

We have options to classify poles, regardless if they are power poles. This function can be found in the Auto-Classify Powerline and Pole Points tool found in the Lidar Module toolbar. 

Can we classify trees based on diameters?

With a classified point cloud the feature extraction tool can extract features representing trees. The features extracted are point features representing the tree and tree coverage polygons representing the spread of each tree. These generated vector features have attributes describing each tree and you can go on to query and filter the extracted tree features by various attribute values. 

Will the building regularization work with circular buildings?

The regularization options in building extraction work to enforce parallel lines and right angles in order to clean up the extraction of rectangular buildings. This will not work effectively to regularize with circular buildings. 

So does the building extraction regularize option use normals?

The regularize option in the building feature extraction tool is based on the horizontal threshold value. This threshold is the maximum distance a point could move in order to make the line segments parallel or perpendicular. 

How does it handle building extraction when there are lots of points on sidewalls and also overhanging roofs​?

The building extraction tool in the Lidar Module can identify features for the roof planes and side walls. The success of this extraction tool will be somewhat dependent on the clarity and classification of the source data and the parameters being used in the extraction tool. 

What kind of detail can be extracted? For example: Curb and Gutter.

The automatic extraction tool in the Lidar Module will work to extract the noted features: buildings, trees, powerlines, and poles. Manual feature extraction for finer features like curbs is available as well through the path profile tool.

How do you extract data to be imported into Autodesk Civil 3D?

Global Mapper supports many file formats for export including DWG, DXF, and LandXML. These formats are commonly used by Global Mapper users looking to export data and bring it into AutoCAD programs. A full list of supported file formats can be found here in the Global Mapper knowledge base

If data in a lidar file is in meters, can we determine a conversion to feet on import?

In Global Mapper you can adjust the vertical units used for display and the default vertical units for processing and export in Configuration. Configuration > Display Options > Elevation Legend allows you to set the units for the onscreen elevation legend, and Configuration > Vertical Options allows you to set the vertical units (metric or statute) used by default in the Global Mapper program. Making these changes will allow you to interact with your data using feet at the vertical units. 

To actually convert the values written into the file you would need to export the data to a new file and in the export options select the vertical units to be feet. 

Any suggestions on the best overlap percentage for a good point cloud generation?

Generally we suggest overlap of at least 60% but this may vary based on your flight pattern and the terrain/features you are looking to model. General image collection recommendations for the Pixels to Points tool can be found here in the Global Mapper knowledge base.

Does pixels to points work with oblique photos?

Yes, the Pixels to Points tool can work with oblique images. When using oblique images consider using the masking tool in the Pixels to Points dialog to remove any sections of images that may contain sky or other areas you do not want to be considered in the point cloud construction. 

For the Pixels to Points function, does it virtually go through Aerial Triangulation? Or it doesn’t, and needs accurate EOs of the photos and camera parameters to create the product like orthophoto?

The single orthophoto generated from the Pixels to Points tool is derived from the tool’s primary output, the point cloud. Pixel matching across overlapping photos and triangulation are used to place points in the point cloud. This point cloud is then gridded into an image to generate the orthoimage layer

Can you edit the exif to update the altitude/elevation of the camera based on the geoid model elevation?

Global Mapper alone does not transform vertical coordinate systems. The Pixels to Points tool assumes coordinates from the images to be WGS84 / Ellipsoid height. After generating the 3D outputs from the Pixels to Points tool you can use Geographic Calculator or GeoCalc Mode in Global Mapper to transform the vertical values for the data. 

Does the “Relative Altitude” in the image file list represent the above ground level height or an altitude relative to the take off elevation?

The relative altitude is taken from either loaded terrain data, or online source data. The online sources used are first 10m NED data (US) then ASTER GDEM and 30m STRM data available worldwide. More specific language from the Global Mapper knowledgebase: “This setting, therefore, overrides the elevation values by specifying a starting ground height for the first input image.” 

Is the height in the terrain painting relative or absolute?

In the Terrain Painting tool, the operations to raise and lower terrain heights will alter the terrain relative to the existing elevation. The operation to set the terrain height will set the absolut terrain height for the painted area. 

Any option to apply a width to the top of the bank?

Using the line brush type and the slope across a line operation in the Terrain Painting tool you cannot set a width for the top of the slope. After creating the bank with the slope across a line operation you can use the set terrain height operation to flatten the top of the bank giving it a specific width. 

How about a ditch?

The Terrain Painting tool can be used to create ditches in existing terrain layers. With options to Lower Terrain Height or Set Terrain Height you can create the bottom of the ditch you are looking to cut and then adjust the slope as needed with the new terrain painting slope operations. 

What about GPU processing?

While it uses the GPU for 3D rendering, not much heavy processing is sent to the GPU. A stronger or dedicated GPU, as opposed to an integrated CPU/GPU, will help to improve rendering in the 3D view and assist with small aspects of the Pixels to Point process.

​Have you ever integrated internal scan data with LiDAR in the Lidar module?

​I assume you are talking about lidar scans in buildings or something similar? If yes, we can certainly import and visualize this kind of data if it is imported from a supported file format. Our automated classification tools are built around using terrestrial lidar data to classify ground, buildings, and vegetation, so you may be limited in doing auto classification work. But, you can still visualize and edit the internal scan data in Global Mapper.

How to measure slope distance between points?

If you are measuring between two lidar points, you use the Path Profile tool and draw a path along the area you are interested in finding a slope for. Once the Path Profile window is drawn, you can use the Measure Tool and select one point, then select another point and right click to stop the measuring. On the bottom, you should see the slope value displayed.

Will we be able to select by a multi sided polygon rather than simply crossing the 3D window?

Currently the sweep selection in the 3D will select features as you click and drag a box across the data displayed in 3D. We are considering various updates to this too including a polygon select option like the one available in the 2D map view. 

Will online tutorials be updated or added for the v22.1 tools?

​I would make sure to follow our YouTube page (BlueMarbleWebinars) to stay up to date if we release any new videos for the latest tools in Global Mapper!


If you’d like to try out Global Mapper and the Lidar Module, download a 14-day free trial and request a demo today! If you are interested in our upcoming webinars, check out the GeoTalks Express schedule. For more information, contact us.

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