Global Mapper for UAV Operations

Flythrough in Global Mapper 18
For many UAV operators, the quest to find an affordable, easy-to-use, yet powerful data processing application has ultimately led them to Global Mapper.

As an inherently versatile and interoperable GIS application, Global Mapper has become an essential component of the geospatial toolkit for companies, government departments, and organizations of every imaginable size and type. While the software’s popularity in certain market segments can be directly attributed to a preemptive marketing strategy by Blue Marble, the same cannot be said of the Unmanned Aerial Vehicle (UAV) industry. Instead, the reason why many UAV operators found and embraced Global Mapper can be attributed to word-of-mouth recommendation from others in the field.

With the rapidly expanding use of UAVs for commercial data collection, a bourgeoning market has emerged for data processing software tailored to the needs of the needs of the UAV community. Consequently, many commercial and open-source software developers have jumped on the bandwagon and have begun the process of creating tools to address this demand. Global Mapper, on the other hand, has been around for almost two decades and has proven to be ideally suited to the requirements of the UAV industry. For many UAV operators, the quest to find an affordable, easy-to-use, yet powerful data processing application has ultimately led them to this remarkable application.

So what role does Global Mapper play in commercial UAV operations?

Mission Planning

High-resolution aerial imagery in Global Mapper
High-resolution aerial imagery and terrain layers can be accessed on-demand providing an initial three-dimensional visual context for a project area.

Global Mapper’s expansive streaming data service provides access to a wealth of invaluable map layers that form the foundation for the mission planning process. High-resolution aerial imagery and terrain layers can be accessed on-demand providing an initial three-dimensional visual context for a project area. Locally available vector files can also be overlaid to address concerns such as property ownership, regulatory issues, potential obstructions, and optimal takeoff and landing sites. Intuitive digitizing and drawing tools can be employed to delineate and measure the extent of the project area and supplementary attributes added to record the flight details in their spatial context. Finally, a high-quality project proposal map can be generated in georeferenced PDF or hardcopy format for sharing with a client or customer.

Imagery Processing

Image rectification in Global Mapper
The software offers a powerful image rectification tool for applying geographic intelligence to captured images by anchoring them to known coordinates.

For most UAV operators, the true value of Global Mapper comes to the fore after the mission has been flown. Transforming raw data into a viable commodity or finished product is Global Mapper’s forte, and image processing is a major part of that workflow. The software offers a powerful image rectification tool for applying geographic intelligence to captured images by anchoring them to known coordinates or manually placed control points. Multiple images can be mosaicked or stitched together to form one contiguous file and the overlapping images can be feathered to smooth the transition from one image to the next. Image manipulation options are also available including contrast, saturation, and transparency adjustment. For advanced users, a raster calculation function can be used to analyze the characteristics of multiband images using a predefined or custom formula, the most common of which is NDVI analysis for vegetation assessment using the red and near infrared bands.

Point Cloud Processing

Increasingly, UAV operators are generating 3D point cloud files during the data collection process. Traditionally this data, often generically referred to as LiDAR, has been collected using piloted aircraft at relatively high altitude resulting in lower density point coverage. As the raw material for terrain analysis or feature extraction, the quality of the final product is intrinsically linked to this point density, so UAV-derived point cloud files are typically superior to those derived from conventional LiDAR collection. Global Mapper, along with the optional LiDAR Module, offers an array of LiDAR processing tools for editing, cropping, and filtering the data. Noise points can be systematically flagged and removed and a vertical quality control process can be implemented to adjust the elevation values to surveyed control points.

LiDAR post processing in Global Mapper 18
Global Mapper, along with the optional LiDAR Module, offers an array of LiDAR processing tools for editing, cropping, and filtering the data.

Terrain Analysis

3D View and Gridding in Global Mapper
Using the LiDAR ground points, a simple gridding process transforms the XYZ values into a raster Digital Elevation Model — a three-dimensional representation of bare earth — in Global Mapper.

For most LiDAR or point cloud users, terrain analysis is the ultimate objective, a process that requires the non-ground points to be initially identified and filtered from the data. Using the remaining ground points, a simple gridding process transforms the XYZ values into a raster Digital Elevation Model: a three-dimensional representation of bare earth. Many of Global Mapper’s advanced analysis functions are derived from this gridded data, including watershed delineation, line of sight analysis, and view shed modeling. For UAV-collected data, one of the most powerful and commonly used terrain-based functions is volume calculation. Global Mapper offers a variety of tools for this purpose from simple pile volume calculation, derived from delineating the bounds of the pile or  depression, to the more complex cut-and-fill optimization process, in which the terrain is flattened to an elevation that equalizes the volume of material to be cut and filled.

Feature Extraction

The advent of UAV-collected, high-resolution point cloud data has led to a myriad of applications for the technology: from vegetation monitoring to archeology. To address the growing need to detect recognizable patterns within the data, several automatic reclassification tools have recently been integrated into the Global Mapper LiDAR Module. Points representing buildings, vegetation, and utility cables can be identified and reassigned to the appropriate LiDAR class. These reclassified points can then be used to extract or create 3D vector features (points, lines, or polygons) of the objects they represent. A manual extraction option is also available whereby custom lines or areas can be created using a series of cross-sectional views through a point cloud. Feature extraction can also be applied to imagery allowing patterns of pixel colors to be used as the basis for creating polygons.

Feature extraction in Global Mapper
Points representing buildings, vegetation, and utility cables can be identified and reassigned to the appropriate LiDAR class. In this screenshot, the Path Profile tool is being used to display power lines.

Data exporting and sharing

No spatial data processing workflow is complete without addressing the essential requirement for sharing the outcome or results and, once again, Global Mapper is well-equipped for this task. Any collected or created data layers, regardless of format, can be easily reprojected and converted to meet the needs of the client. Cartographic layout tools are available for designing printed maps or for generating geospatial PDFs representing the project site. Global Mapper can even create a 3D PDF allowing anyone with a PDF reader to render a three-dimensional model of any 3D data. For UAV applications, one of the most interesting project visualization options in Global Mapper is the creation of a 3D flythrough. Created from the flight path of the UAV and, if applicable, integrating a video recorded during the mission, the display will render the video while following the flight progress on the 2D map. Even without the availability of an accompanying video, the 3D flythrough can be simulated using any loaded terrain or point cloud data and the 3D line feature that is used as the basis for the fly-through visualization can even be exported as a GPX file for use in the UAV’s navigation system.

Flythrough in Global Mapper
Even without the availability of an accompanying video, the 3D flythrough can be simulated using any loaded terrain or point cloud data.

Global Mapper has become an essential application for many research organizations and pioneering companies in the professional UAV field. As Global Mapper continues its evolutionary development, these users will play a pivotal role in shaping the software’s functional makeup to ensure it is meeting the needs of the UAV community at large. If you are not currently using Global Mapper, why not download a free trial copy.


David McKittrick is a Senior Application Specialist at Blue Marble Geographics in Hallowell, Maine.  A graduate of the University of Ulster in Northern Ireland, McKittrick has spent over 25 years in the field of GIS and mapping, focusing on the application and implementation spatial technology. McKittrick has designed and delivered hundreds of GIS training classes, seminars, and presentations and has authored dozens of articles and papers for a variety industry and trade publications.

Back in the Day Part I: Making Paper Maps from Scratch

Map making back in the dayIllustration by Chelsea Ellis
Back in the day, roads and other line features in gazetteers were often traced from source maps and scribed by hand using a variety of line weights and fills.

I left college with a degree in Fine Arts with a concentration in printmaking.

Yes, that’s right, printmaking.

Although I didn’t ever have to ask “do you want to supersize that?” I was somewhat concerned about what employment opportunities would be available to me in the real world with my specialized degree. In my last year at school in 1992, students were advised to pursue opportunities in this new-fangled computer graphics industry. I wasn’t convinced this was the wave of the future, so I settled with the commercial printing industry. I became a map technician for a well-known publisher of traditional atlases and gazetteers.

What’s a Gazetteer? A great question that seems funny today. Nowadays you can go online using your map service of choice (Google Earth, Bing, OpenStreetMaps) type in a place name or an address, adjust your scale and POOF! You can basically produce a map for almost any purpose with just a few mouse clicks.

Wikipedia defines a gazetteer as:

‘‘A geographical dictionary or directory used in conjunction with a map or atlas. They typically contain information concerning the geographical makeup, social statistics and physical features of a country, region, or continent. Content of a gazetteer can include a subject’s location, dimensions of peaks and waterways, population, GDP and literacy rate. This information is generally divided into topics with entries listed in alphabetical order.”

A good analogy might be: a gazetteer is to an atlas as attributes are to features in a GIS database.

Creating a gazetteer involves a fantastic amount of gathering source data, analysis and research, and many waves of mind-numbing proofreading. You need people with surgical attention to detail and an aversion to burnout to make a successful gazetteer. Fortunately, I wasn’t involved in the research or copy editing portions of the process. I was there to make the actual maps, and what fun that was.

Back in the day, roads and other line features were often traced from source maps and scribed by hand using a variety of line weights and fills. I was hired as a map technician, I think, mainly because of my mechanical drawing skills. In the hiring process, the publisher had me take a “scribe test” in which I used sample pieces of scribe coat and a scribe tool to produce lines for a map.

Scribe tool illustrationIllustration by Chelsea Ellis
The scribe tool has a sapphire tip that scrapes clean lines in the scribe coat for map features, essentially creating a negative from the scribe coat.

Scribe coat is a heavy film coated with a material that is easily scraped away using a specialized scribe tool. The scribe tool has a sapphire tip — a real gemstone — that is meant to be dragged along the scribe coat to scrape clean lines for map features, essentially creating a negative. It takes a certain touch to manually scribe: too heavy handed and a gouge could be made in the film underneath; too light handed and a clean line wouldn’t be rendered.

I must have done well in my scribe test, because for the next two months, I hand scribed all of the roads for the Maine state atlas in production and duplicated sheets for printing.

To create “dupes” of my sheets, I dutifully taped a protective cover of newsprint over each corner of the scribe coat sheet (one false move and a dropped sheet could ruin my day) and transported my work to the vacuum-frame room.

The vacuum frame, an essential part of any conventional mapmaker’s work, is an exposure machine that has a large bed fit with a heavy, hinged glass lid.

In the large bed of the vacuum frame, I would lay a sheet of blank, yellow duplication film emulsion side up, lay my work over the film, and close the glass lid. Turning the vacuum frame on, I would hear the vacuum remove the air in the bed, creating a close contact between the original scribe sheet and the duplication film. A timed UV exposure would then create a duplicate image by exposing all of the road lines I created with my scribe tool onto the yellow duplication film. After the dupe was “burned,” I would then run it through an ammonia processor that would transform the dupe film into a layer that would be used in the printing process.

Next … stripping layers into CMYK “flats” and the joy of negative corrections!

To be continued …


Kris Berglund

Kris Berglund is currently the Vice-President of Sales at Blue Marble Geographics and has been with the company for over fifteen years. Kris has been involved with digital mapping technology for over twenty years, and demonstrates a diverse level of experience in cartography, geomatics, technical sales & marketing and business development.