A 1.736Mb PDF of this article as it appeared in the magazine complete with images is available by clicking HERE
If the question "What is mobile mapping and when did it start?" was asked to ten different people in the geospatial industry, it would likely solicit ten different answers. This is because everyone shares different opinions of what mobile mapping truly is and how it began. There are some who believe that mobile mapping includes aerial mapping since airborne sensors collect data from a moving platform. Others might tell you that mobile mapping began with the release of terrestrial laser scanners. Not long after the first static scanner hit the market, companies were attempting to integrate them with GPS receivers and telescoping booms on different platforms. As the speed and capabilities of the terrestrial laser scanners increased, solutions that utilize this LiDAR technology in innovative ways while integrating them with a GPS/INS solution are still considered by many as a mobile mapping solution. Others may add that taking an airborne LiDAR sensor and placing it on a vehicle for testing in a hostile environment qualifies as mobile mapping. Additionally, there are many different mobile mapping solutions in operation that only utilize passive imaging sensors without any integration of LiDAR or laser scanning technology. So, it becomes quite evident that mobile mapping means many different things to many different people.
While all of these different points of view have merit with regards to mobile mapping and mobile LiDAR, the unarguable fact still remains that the first ever mobile LiDAR sensor specifically designed and built for terrestrial mobile mapping and mobile laser scanning came to the market just a short four years ago. Many may not recognize this as the birth of mobile mapping, but it certainly has revolutionized the industry since its debut. This development in LiDAR technology is considered by many to be the birth of an industry as hardware manufacturing companies finally started offering an application specific solution that is designed around a mobile mapping premise only.
Since Optech first launched the Lynx Mobile Mapper, many other manufacturers have started offering their own mobile mapping solutions to the market. These solutions vary widely with regards to capabilities, accuracies, applications, and costs associated with the purchase of a solution. This wide variance in systems and technology often confuses potential end users of the data, as well as, companies looking to procure a mobile mapping system. Because of the many varieties of mobile mapping solutions, a potential system owner must become a resident expert in all of the associated technologies of mobile mapping to include LiDAR, digital imaging, GPS/INS, auxiliary sensors, etc. often making it difficult to decide which system will best fit their business practices and applications.
Hopefully, by addressing some of these general concerns, this article is able to offer some insight into utilizing this fantastic technology. Addressing a few of these concerns in no particular order:
A point cloud is a point cloud/a laser point is a laser point
As a LiDAR community, we know this couldn’t be any further from truth. However, many end users of the data that are contracting services are not as educated as we are on LiDAR technology and the differences in capabilities between sensors. They often don’t have the time or the technical resources to research the technology thoroughly. Without a thorough understanding of what is achievable from a particular system and/or service provider, the end user often finds themselves making a decision based on price and not qualifications or technical capabilities of the best solution for their needs, and this could spell disaster for the entire industry and market. End user education should be the highest priority of the entire LiDAR community. While not all projects require data that can only be generated from the very best LiDAR sensors, it is important to understand that not all LiDAR sensors are capable of meeting the demands of every project. Additionally, while all mobile mapping systems are able to generate LiDAR points that are acceptable for GIS or mapping grade accuracies, very few LiDAR sensors are able to achieve survey or engineering grade tolerances. If the LiDAR sensor specifications will not achieve these tolerances independently, it is impossible for the mobile mapping systems to achieve these tolerances as a complete solution.
Higher laser pulse rates means better data and better solutions
The LiDAR industry has been haunted by this fad for decades. It dates back to the very beginning of the airborne LiDAR market in a time often referred to as the "rep rate wars" referring to the differences in laser repetition rates between airborne LiDAR sensor manufacturers. In the early days of airborne LiDAR, an increase in laser pulse repetition rates (PRR) had a dramatic effect in overall data quality. It could mean the difference between putting one point per square meter on the ground versus putting eight points per square meter on the ground in a swath that would generate a more representative surface model. Also, with an increase in PRR, it allows for an airborne survey to be conducted at higher altitudes or AGLs (Above Ground Level). This is extremely attractive for airborne service providers because it can directly affect their ROI and profit margins on a project. The higher the AGL for each individual flight line while maintaining point density and distribution on the ground will directly impact the coverage of an area per flight line. Covering more project area with each flight line, a project needs fewer flight lines during data acquisition. Since aircraft are expensive to both operate and maintain, the PRR directly impacts the success of an airborne service provider. We still see this evident today as the manufacturers are continuing to push the envelope with innovating new sensors with higher PRR to increase both point densities and flight line coverage area.
However, from a mobile mapping perspective, the PRR has less of an impact on overall project success. While it is still important, the PRR of mobile LiDAR sensors has already reached a point that greatly exceeds what is needed on most projects. The PRR of mobile systems really could be summed up as a "catch 22." Higher PRR means more points on targets and an increase in the likelihood of acquiring data on smaller targets at range. However, with these excessively high PRR’s, the ability to process the data in a timely and efficient manner becomes hindering to the overall success of a project. How important is generating ~7,000 points per square meter on the surface compared to generating ~4,000 points per square meter when the final deliverable files for the end users can only support one point every three feet or one point every five feet in creating surface models? The added time in processing and the time required to properly decimate the data sets into usable file sizes increases the overall project timelines.
In addition, project owners and contracting entities are attracted to the speed and efficiency that mobile LiDAR and mobile mapping can provide for their projects. With higher PRR and larger data sets, processing data efficiently becomes ineffective. The advantages of mobile mapping should be to speed up the entire project life cycle, and not just the data acquisition. Only by speeding up both data acquisition and data processing to deliverables, can mobile mapping truly help in condensing the entire project timeline. If this doesn’t take place, mobile mapping doesn’t offer a clear advantage to surveying conventionally in relation to project timelines.
Finally, more data doesn’t mean better data. In fact, better data could be characterized by the accuracies, precision, the amount of "noise" found in the LiDAR sensor. Appreciatively, Riegl addressed this issue with the VMX-250 and the release of the new VMX-450. In addition to increasing the capabilities of new VQ-450 LiDAR sensor with regards to PRR and mirror speed, they addressed the issue of data integrity and calibration. By calibrating and accounting for the errors of each component throughout the entire optical path of the LiDAR sensor, the VQ-250 and VQ-450 LiDAR sensors are generating unprecedented PRR while achieving accuracies and precision that was previously only obtainable from static terrestrial laser scanners. Mobile mapping system manufactures should follow this trend by making solutions that not only generate "more" data but, more importantly, "better" data.
You must own a mobile mapping system to participate in the market
There have been several different articles published over the last few months regarding work that has been completed by companies renting or contracting manufacturers to conduct the data acquisition on their behalf. This has been a heated topic of discussion from the very beginning of mobile mapping, and it is a concern that potentially can cause irreparable damage to the market and industry.
There are, however, many different views to this dilemma. Some feel that it does the entire mobile market a great service by making it readily available for even small firms to participate in this new emerging market, and many small surveying and mapping firms believe that by contracting the manufacturers to conduct the data acquisition ensures that they achieve the best possible data available without having the worry of introducing a potential future competitor to an important client. Contrary to popular belief, LiDAR manufacturers are not the best resource for collecting project data. There is a huge void between building cutting edge LiDAR sensor technologies and applying them on actual projects in the real world.
Additionally, for hardware manufacturing companies, the fastest and highest level of profit margins and ROI actually resides in system sales. By offering equipment for rental, the manufacturers are hindering their own sales efforts. One might ask, "Why would I ever consider spending the better part of one million dollars when I can just rent your system as needed on a project-to-project basis?" Also, as it should be, a market that requires a great risk often bears a great reward. A potential system owner will face plenty of competition among other service companies. In no way do they want to also compete with their solutions provider. By renting equipment, manufacturers are biting the very hand that feeds them, and they are 100% eliminating any reward for a company who has taken the risk by investing the enormous capitalization costs that are associated with purchasing a mobile mapper.
Every mobile LiDAR service provider in the world goes through a learning curve. The best practices and training offered by system manufactures doesn’t even begin to scratch the surface of what it really takes to be successful on a project that requires engineering design tolerances. Each mobile service provider must form their own protocols and best practice procedures. These are often formed through pain staking trial/error and good old fashion "sweat equity." Once the provider has come up with these standards for achieving the best possible data, they often are not willing to share this information with anyone including the manufacturing companies. It becomes intellectual property and a competitive advantage of each firm. So, the best way to ensure overall project success for a firm interested in utilizing the technology through a third party is to partner with an established and experienced firm that is in the data acquisition business and not in the hardware manufacturing business.
While partnering with existing firms may seem frightening to smaller firms, it is the best way to acquire quality data. The best way to choose a partner is to speak with several of the providers that are available before an actual need on a project comes up. If a company is interested in being a part of the technology without having to spend the initial capitalization, the company should start interviewing and speaking with current system owners immediately. Also, there are very experienced, medium – sized firms like Surveying Solutions, Inc. (SSI) out of Michigan that pose less of a threat for future competition and make the partnering process a lot easier when compared to partnering with a very large national firm.
With so many different mobile mapping systems available on the market today, it is important for companies to consider all possible options to ensure project success. Each mobile system has a place in the market and a best application use. Understanding the strengths of each system and applying the system that excels for a particular application will help to continue the success and acceptance of this market for years to come. Finding the best avenue and business strategy for implementing the technology may not be as difficult as previously thought. While mobile LiDAR is not a "magic bullet" for all projects, it is definitely a powerful tool when utilized properly in the right applications. It is a technology that everyone can utilize throughout the entire industry. The trick is just finding the best avenue of utilization to fit your business model.
Brian Bailey is the Geospatial Services Director for Surveying Solutions, Inc., a provider of mobile LiDAR services utilizing the Riegl VMX-250. Prior to SSI, Mr. Bailey spent four years with Optech as the US Sales Manager for the Lynx Mobile Mapper, where he launched the Lynx product line to the US market. The author can be reached at email@example.com.