What is Mobile Mapping? A Complete Beginners Guide

Mobile mapping is one of the most exciting uses for localisation technology – particularly GNSS/INS technology like ours. This blog is designed to be the ultimate primer on mobile mapping for anyone looking to learn more about mobile mapping technology and mapping systems such as mobile LiDAR. So, what is mobile mapping?

What is mobile mapping?

Any activity that involves surveying something from a moving vehicle is a type of mobile mapping. Broadly speaking, mobile mapping is grouped into land-based and aerial mapping activities. Land-based mobile mapping, also sometimes called road-based mobile mapping, is where the survey is done from a car. The Google Streetview cars are probably one of the most public examples of road-based mobile mapping. 

Learn more about road-based mobile mapping

Aerial mapping, of course, is surveying done from the air. This might be from a small quad-copter drone, or from a larger aircraft, either manned or unmanned.  

Learn more about UAV mapping and manned aerial surveying

Key mobile mapping technology

In any mobile mapping payload (which is the name for the collection of sensors and technology used for the survey), there are some common components: 

1. The sensors used to gather the survey data 
2. The localisation solution 

The process of combining those two datasets is known as georeferencing. Once the survey data has been georeferenced, it has been given a fixed position on the earth, which means that data can be used for its intended purpose.  

A wide range of sensors can be used for the survey. The most common historically has been the camera, creating a photographic image as the survey result. More recently, LiDAR (Light Detection And Ranging) has become a popular method of surveying. LiDAR uses lasers to measure the distance between the sensor and objects in the surrounding environment, producing millions (or even billions) of “points” which make up the survey. The final output from a LiDAR is known as a point cloud, which resembles a 3D model of the area surveyed.

Beyond that, almost any sensor can be used for surveying. Radar and hyperspectral imaging are often used, but we have worked with customers to help them georeference data from a range of different sensors including gas sensing equipment in the past. As long as you can georeference the data with your localisation technology, you can use your sensor in a survey.

Mobile mapping localisation

These days, the most popular method of localisation for mobile mapping is a combination of GNSS data and an IMU (inertial measurement unit). 

GNSS stands for Global Navigation Satellite System and refers to constellations of satellites in space that provide position data. GPS, for instance, is an example of GNSS.

Learn more about GNSS

An IMU is a collection of gyroscopes and accelerometers that measure changes in velocity, acceleration, and angular momentum, which are used to estimate the heading, speed, and orientation (among other things) of an object. An IMU combined with GNSS data is usually referred to as a GNSS-aided inertial navigation system, or GNSS/INS. Combining the two makes the system more robust – the INS allows you to identify any errors in your satellite data, perhaps caused by a drop in satellite coverage, while the GNSS corrects the gradual position drift that any IMU is subject to.

How mobile mapping works

Typically, the mobile mapping process involves the following steps: 

1. Setup: build your surveying payload, making sure your sensors are tightly integrated to give you the best quality output. 
2. Gather the data: conduct your survey, whether on land or in the air, gathering both survey data and localisation data in real time. 
3. Processing: once the data is gathered, you need to combine the two datasets to produce a final result. There are some sub-steps in here: you will likely run some post-processing algorithms on your localisation data in order to maximise the accuracy of that data, and then you will run a separate georeferencing step where the position data is combined with the survey data.

The specifics of the workflow will vary depending on the sensor you are using. For instance, if you are using a mobile LiDAR device, your will need to add in a boresight calibration step before you survey to precisely align the LiDAR scanner and your GNSS/INS, to avoid blurry images.

Benefits of mobile mapping with OXTS

OXTS is focused on what’s known as direct georeferencing. That means gathering location data in real time, without relying on ground survey data. Older surveying methods use pre-surveyed markers on the ground, known as ground control points or GCPs. 

Using an OXTS GNSS/INS is vastly superior to using GCPs for surveying for a few reasons: 

• GCPs have to be placed in the environment before you survey, making them time-consuming to use and not appropriate for every environment. 

• If you place the GCPs incorrectly it can reduce their accuracy or even make them unusable, leading to costly re-surveying. 

• They require large “sidelaps” in your data (overlapping sections) to work at their best. 

By contrast, using a GNSS/INS requires no pre-placement of markers, and no sidelaps. You fire up your surveying payload and get straight to work. 

OXTS offers a few benefits over other direct georeferencing solutions, too. The biggest advantage is the value for money. Many survey-grade localisation solutions cost vastly more than OXTS, while offering only marginal improvements in accuracy. OXTS uses advanced data processing algorithms and careful calibrations to get high levels of accuracy from more economical components, giving you high performance suitable for the majority of surveyors without the high price tag.

OXTS is also highly experienced in sensor fusion, leading the market with products like WayFinder. Since integrating different sensors is a cornerstone of modern mobile mapping, working with a partner who has extensive experience georeferencing a range of sensors will pay dividends during the integration and build phase of your project. 

Limitations and challenges

The main challenge in mobile mapping is preserving the accuracy of your location data, especially in areas where GNSS signal is weaker. This includes forests, where trees block satellite signals, and urban environments where skyscrapers can reflect signals, distorting them and creating what’s known as multipath errors.

Increasingly, surveyors are trying to tackle the challenge of surveying in areas with no GNSS signal at all, such as indoors or underground. This requires localisation solutions that contain additional sensors besides GNSS antennas and an IMU, and integrating them into the payload in a way that allows the payload to move between indoor and outdoor spaces seamlessly. 

On top of the accuracy challenge, the georeferencing process after the survey can be complex. Survey datasets are often very large in mobile mapping, meaning that georeferencing algorithms need to be as efficient as possible – or run on high-powered computers – in order to function. 

None of these challenges is insurmountable – they just require the right technology, the right expertise, and time to get them right. 

Mobile mapping applications across industries

People use mobile mapping technologies for a huge range of activities. Any time that you need to know the precise location of something, mobile mapping technology can help. Here are just a few examples of what it can be used for:

• Cartographers use mobile mapping to create highly accurate maps faster and more efficiently than using outdated techniques such as ground control points. 

• Construction companies often use mobile LiDAR scanners to survey the ground before building starts, and to survey the construction as work progresses to ensure things stay on track. 

• Autonomous vehicle manufacturers will create (or buy from third parties) maps for their vehicles to navigate with using mobile mapping systems – especially ones capable of accurate navigation in environments like cities where GNSS signal is poor. 

• Utilities companies can map their networks to support predictive maintenance and ongoing management efforts. 

• Environmental organisations can use mobile mapping to track things ranging from air quality to the presence of toxins in the soil or a river. 

• Asset management organisations can use mobile mapping to document the location and condition of the assets they manage. 

The list goes on. The applications for mobile mapping are ultimately only limited by the imagination, and the ability to integrate the sensors required. 

The future of mobile mapping

The challenge of improving accuracy in GNSS-denied spaces – and in transitioning between those spaces and open-sky conditions where GNSS signal is strong – remains the next frontier of mobile mapping technology. Handily, the hardware required to do this is often already in place on a surveying payload. One of the leading methods of GNSS-denied localisation is known as real-time sensor fusion, where data is fed into the GNSS/INS in real time to protect accuracy. One of the best sensors for this is LiDAR, due to its high levels of accuracy. If you can analyse frames taken from a mobile LiDAR, identify planes and edges within those frames (such as walls and corners), and track their movement between frames, you can estimate speed, angular momentum, and other data that allows you to accurately estimate your position without GNSS signal. 

It’s a technology that we’ve been actively developing here at OXTS, culminating in our latest product, WayFinder. Best of all, WayFinder works pretty much out of the box, vastly reducing the complexity of integrating it into your payload.

Contact OXTS for your mobile mapping needs

We hope this article has been a useful primer for the world of mobile mapping. If you’re looking to develop or improve your own mobile mapping setup, but aren’t sure how to get there, OXTS can help. Our expertise in localisation technologies and history working with mobile mappers makes us a powerful partner for your engineers, and we pride ourselves on working closely with your technical teams to implement our technology as smoothly and effectively as possible.