Top 5 New Features of Global Mapper v.22

Top 5 New Features of Global Mapper v.22

Global Mapper v.22 is here!  As with all previous releases, version 22 introduces an extensive array of new and updated functionality in virtually all software areas. What hasn’t changed is the price. For under $550 for a single user license, Global Mapper is still unquestionably the best value in GIS software. As a first look at some of its most significant new capabilities, this blog highlights the top five new features of Global Mapper v.22:

1.New Eye Dome Lighting settings in the 3D viewer to help improve the visual display of vector and lidar data: 

While it’s probably not accurate to say that point cloud data appears flat in the 3D Viewer, it is sometimes difficult to discern texture or depth when viewed obliquely, especially when the view is static. The solution to this challenge is the new Eye Dome Lighting feature. This new display option in the 3D Viewer enhances depth perception by darkening the rendering of some points to produce an enhanced perspective of texture.

The best way to see this new tool’s effect on displaying a point cloud in the 3D View is to look at some lidar data before and after the  Eye Dome Lighting feature has been enabled:

2.A new tool for simplifying loaded meshes or TINs

The mesh simplification tool combines the triangle faces of mesh features if they do not significantly contribute to the scene’s shape to simplify and reduce its size. This tool reduces the number of faces, or vertices, in a mesh by collapsing the edges and placing replacement vertices based on the specified method. This process attempts to preserve as much of the mesh’s shape and boundaries as possible while significantly reducing the size and memory requirements for working with the mesh, or TIN,  within Global Mapper or other 3D tools. 

Unsimplified mesh

Simplified Mesh

3.A new Spatial Operations tool for calculating the intersection of layers of the area feature

The new spatial operations tool performs vector overlay procedures on area features to find the intersection of two area layers. By combining this tool with selection by location, or attribute, or repeating with various layers, you can perform a detailed analysis to identify where multiple features coexist. For example, intersection operations are often used in suitability analysis to find the locations that meet two or more criteria.

4.A new Analysis menu option to find the overlap (both percentage and graphical) between two or more lidar, raster/image, and or terrain layers

The new Find Overlap Between Lidar/Raster/Terrain Layers tool can be accessed from the Analysis menu. This tool generates a report showing the overlap percentage between layers. It optionally creates a new raster layer showing overlapping areas – a straightforward and yet useful process! 

5.A new consolidated Digitizer Menu, providing convenient access to all drawing and digitizing tools

It is a testament to the strength of Global Mapper’s vector creation and editing capabilities that the Digitizer has finally been assigned its dedicated menu. Longtime users of the software will have witnessed the continual expansion and reorganization of the Digitizer’s right-click menu and may, on occasion, have struggled to find a particular tool. Thankfully those days are gone.

The Digitizer menu offers a one-stop location for accessing all of the tools needed for working with vector data. Organized into a series of logical sub-menus, this extensive collection of tools includes everything from a simple point, line, and area feature creation to advanced 3D mesh editing functions. If you work with vector data, and virtually all Global Mapper users do, this new menu will streamline your workflow.

There’s much more to Global Mapper!

Global Mapper includes many more data editing, rendering, and analysis tools, and supports over 300 formats of geospatial data, making it the most versatile and interoperable application on the market.  If you’re not familiar with Global Mapper, request a two-week free trial today. If you would like to speak with a representative about how the software can address your unique geospatial challenges, request a demo!

Global Mapper — the all-in-one and affordable GIS software. Contact us today to learn more.

Global Mapper Maintenance and Support

By Rachael Landry

Longtime users know that every purchase or upgrade of Global Mapper includes a year of technical and licensing support. This support, along with our Knowledge Base, videos, webinars, and self-guided training, allows users to explore and experience all Global Mapper has to offer. Our year-long Maintenance and Support Plan (M&S Plan) begins on the date payment is received, and it includes access to all version releases of the software within that 12-month period, allowing customers to utilize the most current version of Global Mapper.

The “Support” Part – The Blue Marble Tech Team is here for you

In addition to providing users access to the most current version of Global Mapper, the M&S Plan also includes the unparalleled technical and licensing support that Blue Marble is known for. Our technical team is ready to answer any questions you might have, from format support to complex workflow scenarios in a timely manner. However, it is important to highlight that technical support is not a substitute for training. Blue Marble offers many training solutions both in person and virtually, including a Global Mapper Certificate program. 

Maintenance and Support Renewals and License Structure

The M&S Plan provides customers with the option to renew their support every year. Purchasing an M&S Plan is not obligatory, as Global Mappers license structure is perpetual, meaning that not renewing it will not affect your license. However, if your M&S Plan has expired, Blue Marble’s technical and licensing support teams may be unable to assist you if you require assistance.

Blue Marble strongly encourages you to stay up-to-date with your M&S Plan, so that you have access to the best software we have to offer. Staying current with your plan guarantees the highest level of software support and service, and that you are receiving the latest software fixes and enhancements.

In the coming weeks, Global Mapper 22 will be released. Make sure that you are eligible to use all the great features and enhancements the new release has to offer by contacting orders@bluemarblegeo.com.

GeoTalks Express – Session 13 Questions & Answers

The thirteenth of Blue Marble’s GeoTalks Express online webinar series entitled An Introduction to Scripting in Global Mapper, was conducted on September 2nd, 2020. During the live session, numerous questions were submitted to the presenters. The following is a list of these questions and the answers provided by Blue Marble’s technical support team.

 

Can you use relative filenames, recursive/subfolders?

With an IMPORT command you can use file paths relative to the location of the saved Global Mapper script you are running. For example, if I have a script saved in the C:\Scripting_Data folder, and data in C:\Scripting_Data\Imagery_Tiles, I can list the filename to an image as only \Imagery_Tiles\19TDK380050.jp2. 

Global Mapper script also supports some built in variables including %SCRIPT_FOLDER% defined as the folder where the Global Mapper script is saved. You can use this variable in a file path parameter values to make file locations dependent on where the script is saved. 

With the IMPORT_DIR_TREE command or a directory loop you do have the option to search subfolders for files to import. Use the parameter RECURSE_DIR=YES to search the subfolders of a directory. 

 

Is it possible to use EPSG instead of the definition of the projection?

Yes, you can load a projection from a recognized EPSG code using the command and parameter LOAD_PROJ PROJ_EPSG_CODE=XXXX. This will change the workspace projection as you would through Configuration > Projection in the Global Mapper user interface. 

 

Is there an option to export eg. image tiles basing on names of shapefiles/areas opened in the project?

Yes, to tile an export based on area features from a vector file, like a shapefile, you would use the POLYGON_CROP_FILE parameter in the EXPORT command along with some other specific parameters. 

The POLYGON_CROP_FILE value would be the filename or loaded layer name for the areas you would like to use as your tiles. In addition to this parameter, use POLYGON_CROP_USE_EACH=YES to export a file for each area in the layer, and POLYGON_CROP_NAME_ATTR with the value being the name of an attribute you would like to use in the exported file names. The attribute value from the  POLYGON_CROP_NAME_ATTR parameter will be added to the end of the specified export file name. 

 

Is it possible to run a script to automate the loading of pictures, run pixel-to-point, DEM, and contour processes?

Yes, with Global Mapper and the Lidar Module registered you can use the GENERATE_POINT_CLOUD command to run the Pixels to Points process. The command is limited by the script format in that you cannot manually place control points or mask your input images via Global Mapper script. These actions would need to be completed in the user interface of Global Mapper. If you would like to use ground control points and/or image masks you may want to create a Pixels to Points workspace in the user interface. and save it. You can then use the saved Pixels to Points workspace in the GENERATE_POINT_CLOUD command in your script. 

After creating the point cloud output use the GENERATE_ELEV_GRID command and then the GENERATE_CONTOURS command to create your elevation grid and contour lines. 

 

Can you import CAD files and export into kml using script?

Yes, CAD formats, like DWG and DXF, along with KML are supported for IMPORT and EXPORT in Global Mapper script. 

 

​Is the / character like a REM type command where whatever you type after is just for reference and runs “nothing”?​

Yes, the / character at the beginning of a line indicates a comment in the script. Global Mapper will not try to run any lines that begin with a forward slash character (/). 

 

Is there a possibility to crop a specific area by script?

Yes, you can crop data during import, export, or when performing other analysis functions by using crop parameters. POLYGON_CROP_FILE can be used to define an area based on an existing file. POLYGON_CROP_NAME can be used to reference a shape previously defined (DEFINE_SHAPE) in the script. 

​What raster formats can you export to?

Global Mapper supports many raster formats for export. ​Formats supported in Global Mapper script along with additional export parameters can be found here in the Scripting Reference section of the Global Mapper knowledge base. 

 

Can you just point to a folder with all the jp2 files and the script will import all jp2 in the folder?

​Yes, you can use the IMPORT_DIR_TREE command to import all files from a directory. To limit the files being imported to a specific type, use a FILENAME_MASKS parameter to filter for a file extension. 

Where can I find the zip file of Scripting_Data? 

The sample data and scripts can be downloaded using this link. To ensure that the script files work as designed, unzip the downloaded folder and copy it to the root of your C drive (C:\Scripting_Data).

 

​With 19-Create_Watersheds.gms as an example, is it possible to join stream reaches into multiple lines starting from the outlet or from a key location. In practice, this would allow export of a series of stream profiles from the head to the outlet for all cases.​

The watershed being created in sample script 19-Create_Watershed is a catchment area script. The area generated shows the area from which water would flow to the point indicated by the parameter FLOW_TO_POS=”3059028.37,497357.79″. 

The COMBINE_LINES command in Global Mapper script can combine lines in a layer, but this would not calculate new watershed attributes for the stream features. Additionally, since the streams come from different locations and flow together into larger streams, a single line from head to outlet would likely not be created. 

 

Alternatively, a batch export of each profile to XYZ could be used and connected via an external code. Just looking for your thoughts on this.

The stream line features generated by the create watershed process are 3D lines and have per vertex elevations. Since this is true you can export the lines to a format that preserves the vertex elevations, like shapefile format using the parameter GEN_3D_FEATURES=YES. Or you can create points at vertices and export those to an XYZ format. To create points at vertices use the EDIT_VECTOR SHAPE_TYPE=LINES CREATE_VERTEX_POINTS=YES. 

 

Will the export script help bypass size issues/Global Mapper memory issues that you can run into when exporting like for example making a points file from a large text file and then exporting as a tab file?

Using Global Mapper script will not resolve memory limitations on your machine. Even though the data may not be displayed when running a script, Global Mapper is still loading the data and executing specific commands like exports. 

If you are seeing consistent issues with a specific workflow or dataset, first check that your machine meets the system requirements for running Global Mapper. If possible share some additional information on your workflow steps including file sizes and feature counts, any settings you use for exports, and any errors you are seeing in the Global Mapper program. 

 

I am running v19.  I have the script folder in the root of C: ask directed. None of the scripts are working. Is it a software version issue?

Even in the older version 19 of Global Mapper many of the provided scripts should run. Make sure the Scripting_Data is unzipped on the root of C:\. What errors or warnings are you seeing when you run the script through the Global Mapper user interface? These errors or warnings may help us to determine why the scripts are not running as expected.

Is Global Mapper right for you? Take a look at the application’s top 10 features

Written by: Cíntia Miranda

Global Mapper is a robust GIS application that combines a comprehensive array of spatial data processing tools with access to an unparalleled variety of data formats at a genuinely affordable price — license cost begins at $549, a fraction of the cost of competing applications.  The latest release includes Remote Desktop Protocol or RDP-enabled licensing for professionals working remotely — a very appropriate tool when many of us are working from home lately.

Developed for both GIS professionals and map enthusiasts, Global Mapper has virtually everything you need in GIS software such as complete interoperability with exceptional data support, powerful data processing in an intuitive interface, extensive raster and vector capabilities, state-of-the-art 3D visualization and analysis, simple installation and setup, and unlimited technical support.  

If you’re searching for a robust and affordable GIS application, here are the top ten features of Global Mapper:

1. Built-in online data access with extensive format support

Global Mapper offers a surprisingly extensive collection of free online data sources available for streaming or download as well as the ability to add in custom data sources of your choosing. Providing support for virtually every known spatial file format as well as direct access to common spatial databases, the application can read, write, and analyze virtually any spatial data.

2. Terrain analysis and 3D data processing

Global Mapper’s analysis functions include view shed and line-of-sight modeling, watershed delineation, volume measurement with cut and fill optimization, customized gridding and terrain creation, contour generation, and much more.  This is an extensive set of data processing tools for a truly affordable application.

3. Advanced point cloud and lidar processing capabilities

The Lidar Module is an optional add-on to Global Mapper that provides advanced point cloud processing tools, including pixels-to-points for photogrammetric point cloud creation from overlapping drone/UAV images, automatic point cloud classification, feature extraction, terrain hydroflattening, and much more. 

4. Data sharing and map publishing tools

When the time comes to share map data, Global Mapper offers numerous options including eye-catching page layout and printing tools, geospatial PDF creation, and direct web publishing to MangoMap, an affordable and easy-to-use online map service. Global Mapper also offers advanced page design and layout tools, including multi-page map book creation.

Multi-layered maps can be published to an online MangoMap account directly from Global Mapper v21.

5. Scripting and batch processing

Global Mapper users can automate most routine data processing functions using simple, text-based scripts or the built-in Batch Processing tool. The scripting language is simple and intuitive with a straightforward command and parameter structure mirroring many of the multi-step procedures that can be performed within the interface.

6. Advanced Image Processing

Global Mapper includes a powerful set of tools for processing imagery or raster layers. The image rectification tool allows any image to be positioned, scaled, aligned, and spatially distorted to create a geographically accurate raster layer. The powerful vector extraction tool can be used to create polygons from a range of colors in a raster layer. Image tiling, mosaicking, blending, cropping, feathering, and visual manipulation options provide the means to adjust the display and characteristics of any raster data layer.

7. Feature label creation and management

Professionals working in cartography say that the format and layout of a well-designed map always need some level of human input. Vector labels in Global Mapper can be assigned to their own layers, which makes formatting, moving, rotating, and deleting individual labels much easier. 

Label formatting in Global Mapper makes producing high-quality maps easier and faster. The screenshot above shows the repositioning of individual labels in a label layer.

8. Digitizing and Vector Editing Tools

When it comes to creating or modifying vector data, Global Mapper’s Digitizer provides a vast array of functions. From simple point, line, and polygon creation to COGO for manual geometric input, the Digitizer has all of the tools you need to create and manage vector layers. Specialized tools are also available for creating a custom grid, buffers, range rings, or virtually any geometric object. Supplementing these drawing tools are a large collection of attribute management and data visualization tools for creating thematic representations of vector data.

9. The ability to record a fly-through path using the fly-mode and walk-mode in the 3D Viewer 

Global Mapper not only is able to record fly-through videos, but it also allows users to “draw” a fly-through path by recording their movements in fly-mode and walk-mode in the 3D Viewer. Since the fly-through feature in Global Mapper is an easy way to create videos of 3D data and terrain, it’s commonly used for real estate and property management, planning drone or UAV flight paths, or simply creating a compelling presentation of your GIS data to stakeholders.

Global Mapper users can “draw” a fly-through path by recording their movements in fly-mode and walk-mode in the 3D Viewer.

10. A free mobile version

Global Mapper Mobile is a free app for iOS and Android devices that offers field viewing and data collection. It displays any supported data from the desktop software, streamlines data collection, and efficiently transfers data into the desktop software.  A professional-grade application is also available for purchase from the Apple App and Google Play stores.

There’s much more to Global Mapper! If this list piqued your interest and you’d like to find out if Global Mapper is the right GIS application for you, download a 14-day free trial and request a demo today!

GeoTalks Express – Session 12 Questions & Answers

The twelfth of Blue Marble’s GeoTalks Express online webinar series entitled Global Mapper Tips and Tricks – Part II, was conducted on August 19th, 2020. During the live session, numerous questions were submitted to the presenters. The following is a list of these questions and the answers provided by Blue Marble’s technical support team.

 

How do you get the different binning method options (like variance) in the grid creation options?

The additional binning method options, Binning (Variance) and Binning (Median Value), in the Elevation Grid Creation tool will be available in the Global Mapper  Lidar Module version 22.0, which is being released later this year. 

 

I notice your current windows “order of presentation” seems reversed from my own experience. I experience the first loaded being placed “under” the next loaded data.

You can reverse the order of presentation for the layers in the Control Center with a right-click option. Right-click on Current Workspace the Control Center and select the option to Display Layer List In Reverse Order (Last is Drawn First).

 

When you feather elevation data can you then export the new feathered DEM?

Yes, Global Mapper will export the data that is displayed including any feathering settings for image or elevation layers. To capture these display settings involving multiple layers be sure to export all elevation layers involved. 

 

Is it possible to make a vector data transparent in Global Mapper?

You can completely hide a vector layer of features by unchecking the layer in the control center. There are some Null or No Symbol vector feature styles you can set to use for a layer or specific features. This will keep the features in the workspace and technically displayed, but they will not have a visible symbol used to display them. 

 

Can I export .shp data to .kml file complete with text display and full attribute data?

Yes, you can export vector features with attributes to KML/KMZ format. When exporting to this format be sure to choose the second Feature Descriptions option for Feature Description, Links, and Attribute Values. This KML/KMZ export option will be sure to export the attributes associated with each feature. 

 

Does Global Mapper have a function to create TIN? 

You can generate a gridded TIN and a vector TIN layer with the Elevation Grid Creation tool using 3D vector source data. When setting up the Grid Creation Options choose the Grid Method as Triangulation (Grid TIN of Points) to generate the gridded TIN layer. If you would like to also save the vector TIN, check the option to Save Triangulation Network (TIN) as a Vector Layer

 

Can these webinars be downloaded and saved to a pc or are they only available for review on YouTube?

Currently, the recorded webinar sessions are available on Blue Marble’s YouTube Channel. As a registered attendee, you will receive an email granting access to all of the GeoTalks Express session recordings. 

 

What happens when the attributes are null or blank?

With the Info Tips, if a feature has no label the Info Tip will display the text <NO LABEL> in place of the feature label. 

If you have configured the Info Tips to display a custom string of attributes and a feature does not contain a value for one of the attributes, the Info Tip will not display a value, it will just show a blank space for that attribute value. 

 

Can you set up a hotkey to toggle info tips on and off?

Unfortunately at this time there is no shortcut to toggle the Info Tips on and off, and there is no option to create a custom shortcut for this function. 

What you can do is add a custom toolbar button and place it on an existing toolbar to more easily turn the Info Tips on and off without having to navigate the view menu. 

 

Can we see info tips for 3D Points in 3D Viewer?

The Info Tips popup does not appear in the 3D viewer, it is only displayed when working in the 2D view. You can select individual points or features with the digitizer in the 3D view to display label and feature type information for the feature, but it will not be the information set up for the Info Tips. 

 

Can we merge DEM at various pixel sizes?

To merge multiple elevation layers, export them to a new file. When exporting elevation layers you will have the option to set the sample spacing or pixel size for the exported file. By default, this will be set to an average of the loaded layers, but you can alter these values to your desired pixel size for the merged file. 

 

Can you burn a DEM, like you want to change the depth of the river?

If you have a 3D area feature representing the river area, you can create a section of elevation grid for the river area only. After creating this smaller elevation grid, display the layers together and export them or use Combine/Compare Terrain Layers to combine them into a new gridded elevation layer. 

Alternatively, you could generate points from your existing elevation grid using the Layer Menu option to Create Point Features at Elevation Grid Cell Centers, and then create a new elevation grid layer using the generated points and your 3D river feature. 

 

Will there be a webinar on the LIDAR module?

We have some existing videos and recorded webinars on the Lidar Module available here on our YouTube Channel including this GeoTalks Express session on why you may need the Lidar Module. I also recommend this playlist on Lidar Processing in Global Mapper with the Lidar Module

 

Will the “Info Tips” work for “View in Google Earth”?

The Zoom to View in Google Earth option opens Google Earth on your machine. Info Tips are a function of Global Mapper and therefore will not work in Google Earth. 

 

After you split the layers, can you reverse them back into one?

There is no undo function for splitting a layer into multiple layers. In Global Mapper you do have the ability to select and copy (ctrl + c) and paste (ctrl + v) features between layers or to a new layer. You can select all the features in the split layers to then copy and paste them into a single layer again. 

Another option would be to export multiple layers to a single file in order to create a new un-split version of the layer. Load the exported layer into Global Mapper to see all the features appear in a layer together again. 

 

Can you bring in the Google Earth image to Global Mapper?

If you are able to save an image from Google Earth in a supported format, you will be able to load that image into Global Mapper. For the image to automatically display in the correct location in Global Mapper it will need to be saved as a fully georeferenced from Google Earth.  You can also render high-resolution imagery similar to Google Earth using the Online Data function.

 

Do the Info Tips work on 2 dem files?

The Info Tips can be set to work on multiple elevation files. In the Configure Info Tips dialog check the option to Include Values from All Layers Under Cursor to display the Info Tip information for multiple overlapping layers at the cursor location. 

 

Can you produce volume info between 2 of these contours like a stage storage?

If you have the source elevation layer you would need to limit the elevation grid layer to only display elevations between the contours of interest and then calculate the pile volume for the area. 

To restrict the elevation grid layer elevations open the Layer Options and on the Alter Elevations Tab, set the Minimum and Maximum Valid Elevations to the contour intervals you are interested in. Be sure to check the box to Clamp Out of Bound Values to Valid Range so there are no holes in the altered elevation grid. 

Next, use the digitizer to select the contour that bounds the area you would like to measure (the lower elevation for a pile, the higher elevation for a depression), right-click, and select Analysis/Measurement > Pile Volume

If you do not have the source elevation grid and only have the contour lines, create an elevation grid from the desired contours, and then calculate a pile volume using the contour lines and generated elevation grid. 

 

What size would a PDF be like that one?

When exporting data to PDF or 3D PDF format you do have options to specify the page size and orientation for the generated PDF file. The file size of the generated PDF depends on the resolution and size of the data you are exporting to this format.  For the example used in the presentation, the file size was a little over 5MB.

 

Can we apply display transparency to Google Earth displays?

Altering the display of the Google Earth imagery would be done in Google Earth, not Global Mapper. 

You can export raster imagery with transparency applied from Global Mapper to KML/KMZ format and load that file into Google Earth. In the KML/KMZ Export Options be sure to select the Export Image Format as PNG to support the image transparency in Google Earth. 

 

​How do I import custom shaders I set up in previous version​s?

From the Shader Options in the Configuration dialog box, you can choose to Edit a custom shader. There you should be able to Save to Surfer CLR File. You can then share this file to another machine or user and they should be able to create a custom shader and choose to Initialize from Surfer CLR File

If you are working in the current version 21.1 of Global Mapper, you can use the Import/Export User Settings option to share shaders and other Global Mapper settings from one machine to another. 

Terrain Layer Support in Global Mapper Mobile v2.1

Written by Jeff Hatzel

One of the many new features in Global Mapper Mobile v2.1 is support for terrain layers, which introduces a variety of new functions and settings within the app. These new tools add to an already robust feature set that help to extend  the reach of your GIS. While much of this functionality is available in the free version of the app, some more advanced options are part of the optional Pro Module. 

Features available in the base version of the app:

Prior to the release of Global Mapper Mobile v2.1, a terrain layer exported from the desktop version Global Mapper was handled as a simple raster layer, without any elevation information.  The new functionality recognizes terrain layers and their respective elevation information and metadata.

All terrain layers will be rendered using the Atlas Shader, one of the default shaders in the desktop version of the application. Users can also control whether hill shading is enabled via a new setting found in the Configuration settings in the mobile app. 

Terrain data is displayed using the Atlas shader, with shading enabled by default (left). A setting found in Configuration allows users to disable hill shading if necessary (right).

Navigating to the Control Center within Global Mapper Mobile will feel familiar to users who work with the desktop software. The layer’s elevation range, units, and other related information are now available when viewing the metadata for a terrain layer. This provides a useful reference for users when in the field, providing situational awareness in relation to their data and surroundings.

Terrain layer metadata now shows relevant elevation information associated with the layer, including elevation range, units, and other pertinent information

The addition of terrain layer support to Global Mapper Mobile v2.1 also helps to expand location information by providing elevation information at a specific location. Enabling either Crosshair or GPS and Crosshair location mode will report the elevation values of the terrain at the crosshair location. This displays specific elevation information for a given location from a source other than the device’s location services.

The elevation value of a given location can be viewed when using a crosshair-based location option. As you pan and zoom on the map, the elevation value will update based on the loaded terrain layer.

Advanced options in the Pro Module:

Navigating to the new Shader Options section within Configuration provides Global Mapper Mobile Pro users more options to customize the terrain data. The Shader Name option allows access to any of the terrain shaders that are built into the desktop version of the software.

Users who need to simulate water level on their terrain data will find the Display Water Level settings beneficial to their workflows. Whether modeling water level rise or trying to understand what changes in water level will look like on the landscape, users can control when this is enabled, and at what elevation water is displayed.

Terrain layer support is just one of the many new features in Global Mapper v2.1. If you’re interested in exploring the app further, visit Global Mapper Mobile v2.1 for details. The app is also a free download from the Apple App Store and Google Play Store.

Lidar Quality Control in Global Mapper

Written by: Mackenzie Mills

As more and more individuals independently collect 3D data using  drones equipped with Lidar sensors, it is important to discuss the accuracy of the data. Analysis performed using point cloud data is only as accurate as the source data. When working with 3D data you must worry about not only accuracy in the x and y directions, but the elevation, or z, component. This z value usually contains the most variation or error. While GPS receivers provide accurate horizontal information, they can struggle with vertical accuracy. RTK or PPK systems can help improve location information, but can be prohibitively expensive to include in a drone set up. An alternative would be to survey ground control points for use in post processing to help improve the accuracy of your point cloud.

To check for vertical error and correct it, those surveyed ground control points can be used with Global Mapper’s Lidar QC tool.

This Lidar QC tool, included in the Lidar Module of Global Mapper, compares control points with nearby points in the point cloud layer to measure the elevation difference between the two. Before the point cloud is adjusted, the tool provides a report showing the compared points and elevation difference between the point cloud and control points. After reviewing these metrics, you can then choose to apply the adjustment to the point cloud layer.

The adjustment of the point cloud is determined by interpolating a best fit surface for the area of the point cloud based on the elevation differences calculated and reported by the Lidar QC tool. This method allows the point cloud to be adjusted accurately even if there are differing degrees of vertical error in different areas of the cloud.

To look closer at the process and options available in the Lidar QC tool, we will work through an example.

To begin, ensure a point cloud layer and a layer of 3D ground control points have been loaded into a Global Mapper workspace.

Opening the Lidar QC tool from the Lidar Toolbar, select the point cloud layer and control point layer to use. You do have the option to use only selected 3D points as control points instead of using a whole layer of point features.

The maximum distance parameter in the Lidar QC setup determines how far from each control point Lidar returns will be considered and compared to the control point elevations.

The maximum point cloud returns to consider determines how many Lidar points will be compared to each control point. After the maximum number of point cloud points is reached for each control point, the program stops the comparisons even if all the returns within the maximum distance have not been considered.

Clicking the OK button will generate the Feature Measurement Information seen below. To generate the feature measure values for each control point, the Lidar QC tool uses inverse distance weighting (IDW) to determine the point cloud elevation at the coordinate location of each control point. The reported statistics show the point cloud elevation (LIDAR_ELEV), control point elevation (ELEVATION), and the elevation difference (ELEV_DIFF) for each control point.

This is where you could stop if your elevation differences are within your accepted error margin. Additionally, the feature measure metrics reported by the Lidar QC tool are added as attributes to the control point vector features in Global Mapper so you can look up and reference these values later.

If the elevation difference exceeds your accepted error, you can choose to Fit Lidar to Control Points from the Feature Measurement Information dialog. This will use an interpolated best fit surface determined by comparing the point cloud to the control points to vertically adjust your point cloud layer(s) to better fit the control points. As you can see in the path profile below, the adjusted point cloud is several meters above the original

Although we have been discussing this tool in the context of Lidar data, you can use it with any point cloud, such as those constructed from drone images. By ensuring the accuracy of your point cloud, you will have a more accurate terrain grid, contour lines, and other analyses derived from the quality-controlled point cloud layer.

Working with Bathymetric Data

By: Katrina Schweikert

Global Mapper is well known for its file format support and terrain analysis capabilities. Perhaps what is less well known is the way the various data analysis tools in Global Mapper can be used to generate and analyze bathymetric data. 

Bathymetry is the study of topographic landforms below the water, such as on the ocean floor, the bottom of a lake, or even the bed of a river. Given that over 70% of the earth’s surface is covered with water, this branch of 3D analysis is extremely important in understanding the characteristics of the planet. What follows is an exploration of some of Global Mapper’s analysis and visualization techniques that are relevant to the bathymetric analysis. 

Great Barrier Reef Depth model obtained from Geoscience Australia

Bathymetric Data Support

Global Mapper provides support for over 300 file formats, and many of those include formats for bathymetric data, marine navigation, and remote sensing of subsurface data. Here are some examples: 

  • Marine Navigation and Nautical Charts (S-57 and S-63 with s-52 symbols, NOS/GEO, NV Verlag, PCX,  and others)
  • Sonar, Sidescan sonar and Bathymetric Sounding data (Lowrance Sonar, XTF, HTF, and others) 
  • Gridded Bathymetric Data (BAG, DBDBV, Hypack, IBCOA, GRD98, NITF, various other terrain formats such as netCDF, GeoTiff, ASCII grid)

Bathymetry in a DTM

Gridded bathymetric data provides various visualization and analysis options when loaded into Global Mapper.   The preformatted elevation shaders or a custom shader can be used to find the best color scheme to show depths of submarine landforms. Terrain Shaders can also reveal the slope steepness and slope direction of underwater topography. 

Displayed in the 3D viewer, gridded bathymetric data comes to life with draped imagery and charts, water level visualizations, and any other reference vector data. Quickly and easily generate elevation profiles, or a series of sequential cross-profiles using the Path Profile tool and Perpendicular Profiles setting. 

3D view of bathymetric data with path profile cutaway showing a shipwreck site in the Gulf of Mexico

Combining data from different surveys and fusing data from multiple sensors is as easy as loading in the datasets and ordering the layers. The analysis and visualization tools can automatically merge the various inputs to take data from the topmost layer or choose to view and compare the data from multiple surfaces simultaneously. There are also options for cropping, aligning, feathering, and comparing to create a more seamless integration between disparate datasets. 

Analyzing Bathymetry as a 3D Point Cloud

Global Mapper provides tools for converting existing sensor data such as sonar or soundings to a 3D point cloud; or for sampling existing gridded data to create an array of 3D points at the pixel centers. This enables the automated classification algorithms of the Lidar Module, which can be used to identify the seafloor and identify or remove other subsurface structures or topography. This powerful tool has been used for shipwreck detection and modeling, as well as identification of other subsurface features. 

Subsurface Contouring

Global Mapper includes an easy-to-use tool for generating precise depth contours and shorelines from gridded bathymetric data. The resulting line features can be edited and stylized in a variety of ways and combined with other datasets to create custom bathymetric charts. Alternatively, the areas enclosed by contours lines can be filled to create polygons that show the water extent at different depths or sea levels. 

Contour lines colored by elevation combined with other basemap data to create a custom chart

Measurement and Volume Calculation

Global Mapper provides various tools for calculating two- and three-dimensional measurements. In the 2D map view, the Path Profile window, and the 3D Viewer linear distances and areas are measured using a simple drawing function. Volume can be calculated from bathymetric data by either defining a height or by calculating numerous volumes across a range of water heights. Volume can also be measured by defining a plane or comparing the bathymetric data to a surface grid. This provides various options for water volume calculation. 

Flood Modeling

By combining bathymetric data with terrain data and using tools such as the watershed analysis and water level rise tool it is possible to discover flood extents, flow accumulation, and perform other hydrographic analysis. 

Employing the various terrain editing and terrain creation functions, Global Mapper can be used to create hydro-enforced DEMs or other modified surface models. These can be analyzed within Global Mapper or exported to various formats to support analysis in other applications. 

Temperature and other Measurements

The bathymetric analysis may also involve other gridded datasets such as surface temperature, salinity, gravimetric data, and various other measured values. These datasets can also be visualized, rendered in 3D, and contoured to provide additional insight into the dynamics of lakes, oceans, and other water bodies. 

The latest version of the Global Mapper and Lidar Module include several enhancements, many of which apply to bathymetric data analysis. If this blog piqued your interest and you’d like to find out if Global Mapper is the right application for you, download a 14-day free trial and request a demo today!

How Pixels to Points Works

By: Katrina Schweikert

The Pixels to Points tool in Global Mapper’s Lidar Module uses a process of Automated Aerial Triangulation to reconstruct the 3D scene present in overlapping images. This computationally intensive process may seem like magic, but it relies on basic concepts of vision and photogrammetry. Photogrammetry is the science of taking real-world measurements from photographs. Let’s pull back the curtain to reveal how this process works. 

What is Aerial Triangulation?

Based on photogrammetry techniques, the location, size, and shape of objects can be derived from photographs taken from different angles. By combining views from multiple images, the location of distinct parts of the image are triangulated in 3D space. This is similar to how depth perception works with two eyes; since the object in front of you is viewed from two slightly different angles, the brain can perceive how far away the object is.

Diagram of depth perception

In traditional photogrammetry with stereo-image pairs, the two angles of the image allow the photogrammetrist to measure objects in the image and determine their real world size. With automated techniques using many overlapping images, the entire 3-dimensional nature of the scene being photographed can be reconstructed. 

Photogrammetry measurement diagram

What are the steps in Automated Aerial Triangulation?

Automated Aerial Triangulation involves a number of steps to get from the original images to 3D point clouds, terrain models, textured 3D models, and orthoimages. The first step is to detect distinct features in each image, and then match those features across the adjacent images. The challenge is to automatically detect distinct features that may be at different scales and rotations in each of the images. 

Features detected in two images, with lines showing the matches found

After the features are tracked through the images, the initial reconstruction begins with a process called Structure from Motion (SfM). In the context of mapping technology, the structure of the 3D scene is revealed based on the motion of the camera. This process calculates the precise orientation of the cameras relative to each other and to the scene, and builds the basic surface structure of the scene. This is the point where the selected Analysis Method is applied. The Incremental Analysis Method starts with a set of the best matching photos, and incrementally adds the features from subsequent images into the scene to build the 3D reconstruction. This works well for drone-collected images collected over a large area in a grid pattern. The reconstruction will typically start somewhere near the center of the scene, and work outwards. The Global Method, by contrast, takes information from all of the images together and builds the scene all at once. This makes for a faster process, but it also requires a higher degree of overlap between adjacent images. This is recommended if the images are collected focusing on an object of interest, such as a building, especially when all of the images focus on that central area or object. The result of the Structure from Motion analysis is a sparse point cloud that builds the basic structure of the scene, and a set of precisely oriented cameras that show where and in what direction the images were taken relative to each other

Example of sparse point cloud with camera frustums

The final step of the Automated Aerial Triangulation process involves filling in additional details from each image that was calibrated as part of the scene. This process is called Multi-view Stereo. It involves calculating the depth of each part of the image (i.e. how far away it is from the camera), and then fusing those depth maps to keep the points that appear in multiple images. 

Depth map and confidence map based on overlap with other images

This process generates the final dense 3D point cloud. Based on the options selected, there may be further processing to convert the point cloud into a refined mesh surface (3D Model) that is photo-textured by projecting the images onto it. This option also produces the highest quality orthoimage, removing relief distortions based on the 3D mesh surface. 

What factors impact Automated Aerial Triangulation?

Lens Distortion

An important initial step in the Pixels to Points process is removing the lens distortion in the image. While the photograph may appear as a flat image capture of the target area to the untrained eye, most photographs contain some distortion, particularly towards the edge of the image, where you can see the effect of the curvature of the camera lens. Pixels to Points will remove distortion in the image based on the Camera Type setting. Most standard cameras need correction for the basic radial lens distortion in order to create an accurate 3D scene. The default camera type setting, ‘Pinhole Radial 3’, corrects for the radial lens distortion (using 3 factors). In some cases it might be beneficial to use the ‘Pinhole Brown 2’ camera model, which accounts for both radial distortion and tangential distortion, where the lens and sensor are not perfectly parallel. 

Image with distortion and processed undistorted imag

Some cameras have the ability to perform a calibration, which automatically removes distortion in the image. If the Pixels to Points tool detects from the image metadata that the images have been calibrated, it will switch to the ‘Pinhole’ camera model. If you know your images have already had the distortion removed either by the camera, or some other software, choose the ‘Pinhole’ camera model, which will not apply any additional distortion removal. The final two Camera Type options account for the more extreme distortion of Fisheye or Spherical lenses. Select these options if appropriate for your camera. 

Focal Length and Sensor Width

An important part of transferring the information in the image into a real world scale is knowing some basic camera and image information. The focal length and sensor width values allow for a basic calculation of how large objects are in the image, and thus how far away they are from the camera. What is calculated using these values is a ratio between a known real world size (the sensor width) and the pixel equivalent of that size in the image. This is a starting point for reconstructing the 3D scene. Focal Length information is typically stored in the image metadata. Global Mapper includes a database of sensor widths based on the camera model, however, you may be prompted for this value if your camera is not in the database. You can obtain this information from the device manufacturer. 

Image Position

The basic position of each camera is typically stored in the image metadata (EXIF tags). With a standard camera this location is derived from GPS, from which average horizontal accuracy is within a few meters. There are a few ways to improve the accuracy of the resulting data based on the desired accuracy, and decisions about cost vs. time spent. 

Height Correction

The GPS sensors contained in most cameras may have sufficient horizontal accuracy for some applications. However, the corresponding height values are usually less accurate and are based on an ellipsoidal height model. A basic height correction can be performed using the options for Relative Altitude. This will anchor the output heights based on the ground height where the drone took off (the height of the ground in the first image). You can enter a specific value, or Global Mapper can automatically derive the value from loaded terrain data or online references (USGS NED or SRTM). 

Ground Control Points

One way to correct the position of the output data is through the use of Ground Control Points. This is a set of surveyed points with known X,Y,Z locations that should be evenly distributed throughout the scene. The measured ground control point locations need to be visually identifiable throughout the corresponding images, so it’s common to use a set of crosshairs or targets placed on the ground throughout the collection area before the images are captured.

 

Ground Control Points can be loaded into the Pixels to Points tool and the corresponding locations identified in multiple input images. This will align the scene based on the control points taking precedence over the camera positions. This procedure is a more time-intensive option, but is streamlined through a process whereby the images containing each point are highlighted, It is also possible to use Ground Control Points after the output files have been generated. Global Mapper provides various tools for this, including 3D rectification and the Lidar QC tool, which can also provide accuracy assessment information. 

RTK and PPK Positioning

Hardware manufacturers provide options for improving the accuracy of the positional information by communicating with a reference base station in addition to satellites, and by performing additional corrections based on available information at the time of the image collection. This includes both Real-Time Kinematic and Post-Processing Kinematic options. With some systems, higher accuracy positioning information is written into image metadata, which can be used directly in the Pixels to Points tool. Other systems may save the higher accuracy positions in a text file, in which case you will want to load your images into the Pixels to Points tool and use the option to Load Image Positions from External File

 

Understanding the variables and data requirements for the Pixels to Points tool and other SfM processes will help you to collect images better suited for processing. In turn, this will create higher quality results for further geospatial analysis.

The latest version of the Global Mapper Lidar Module includes several enhancements, many of which apply to the Pixels to Points tool for generating point clouds and 3D meshes from drone-captured images. If this blog piqued your interest and you’d like to find out if the Lidar Module of Global Mapper is the right application for you, download a 14-day free trial and request a demo today!