Seven or eight years ago the concept of Google Earth seemed a far flung idea, the thought of making that very expensive aerial photography was inconceivable, however such online applications have changed the way we look at the world (quite literally) forever. So what is in store for the future as aerial and other imaging technology advances? James Eddy, Technical Director of Bluesky investigates.
In just a few years a new generation of maps have become mainstream. How long will traditional cartographic methods of creating maps from aerial photographs and field surveys continue. New technology has meant a step change in mapping. We are now in the era of rapid digital data capture, processing and dissemination,, and perhaps most importantly greater understanding Anyone with internet access can now be a cartographer with the introduction of crowdsourced mapping.
Before we delve too much into the future it is worth looking at the data capture technology that is evolving today. The latest generation of digital survey cameras not only offer exceptionally high clarity and resolution, but have better shadow penetration and larger radiometric range. They also capture sufficient metadata to allow the rapid production of products such as Digital Terrain Models (DTM) and orthophoto. Sensors also simultaneously capture Colour Infrared (CIR) data used for creating maps showing such things as vegetation health and ground water. But aerial survey has moved on from just aerial photography, specialist sensors are now affordable and commonplace, and not just the domain of universities and research institutes.
One of the biggest benefits of the digital era is perhaps the data processing. Gone are the months of post processing to digitise and orthorectify the imagery. GPS and IMU (inertial measurement units) capture the location and attitude of the camera or sensor whilst it captures an image to centimetre-level accuracy. This saves a significant time in during post processing. It is getting to the point whereby fully orthorectified aerial photography will be created in flight, allowing new data to become available for use minutes after it has been taken. Once Galileo and the Chinese Compass GNSS systems are fully operational, we may see further improvement in accuracy, and perhaps completely eliminate the need for any ground control.
Medium format aerial digital cameras, which can fit in a suitcase, are also coming to market and these will allow high quality photography to be acquired at a much lower cost. The use of Unmanned Aerial Vehicles (UAV’s) such as drones or remote controlled helicopters will become commonplace, as sensors become smaller and data storage continues to improve, and hopefully Air Traffic become more accepting. These developments reduce the cost of aerial mapping overall allowing more regular surveys and more specialist surveys for new developments, environmental monitoring, natural disasters and public safety or security planning.
Earth observation satellites are often crammed with a multitude of sensors capable of measuring a wide range of the electromagnetic spectrum to monitor the land, atmosphere and the oceans, but usually on a macro scale. Whilst not all of these sensors would be suitable for use on an aircraft or UAV, some would allow us to monitor the earth on a more micro scale, a street corner rather than a city. For example with the need to create a sustainable environment, there is an increasing interest in airborne thermal surveys; satellites have carried thermal sensors for many years but new microbolometer thermal cameras designed specifically for airborne surveying allow high precision thermal mapping are now emerging. These are already being used by local authorities in Europe to measure the heat loss from buildings in order to improve energy efficiency in their communities. However there are also other applications such as determining the ‘heat island’ effect of large conurbations or the effectiveness of air conditioning and power lines.
Airborne remote sensing technology is evolving rapidly with other types of sensor. Lidar systems for example are now widely used and generally accepted mapping sensors with many more applications than just measuring the height of things. Bathymetric lidar meanwhile is allowing water depths to be mapped quickly and accurately for the first time along coastlines, estuaries and lakes. Sensors are also evolving using longer ‘microwave’ wavelengths such as Synthetic Aperture Radar (SAR) which allow data collection day or night and in almost any weather conditions. Multispectral and hyperspectral sensors have been around for a while, but with smaller, lower cost sensors, improved analysis of the data, greater understanding of the data, and most importantly a greater need to monitor the environment, we will perhaps see an increase in the use of these types of sensor.
With the threat of global warming and the ongoing threat of natural disasters, there is a growing interest in the environment. This has led to a demand for the monitoring of change, whether natural or man made. . It has been acknowledged that remote sensing (and not just satellite) is a valuable environmental monitoring resource, with the setting up of GMES by the EC and the European Space Agency. This will bring about more regular surveying using a wide range of sensors is allowing scientists to build a much more complete picture of the environmental conditions on the ground. Accurate models can be created to show the impact of, for example, rising sea levels, increasing pollution or illegal logging. Over the coming years GMES will enable earth observation (EO) data to be used in mainstream applications by organisations who are not traditional EO data users.
Environmental issues will also lead to an increase in the ongoing monitoring of the Earth. More frequent surveying will allow developments and the terrain to be remotely monitored with regular automated mapping of changes on the ground. However, the biggest development might be in near real-time monitoring. Currently satellites offer opportunities for near real time data capture, however there is no reason that an aerial survey could not be carried out on a regular basis to give near real time data. For example, traffic queues and air pollution could be monitored and transportation policy adjustments made every day.
With the improving range of airborne sensors highlighted above, one of the most important developments in the future will be multisensor data fusion. Here the integration of data into a single multi-layered dataset will give immediate and more comprehensive information of the situation on the ground. Data fusion also applies to other geographic information. So, there will be an increasing trend to integrate existing GIS layers and geo-referenced data held on other systems such as street lighting and traffic flow layers as well as data from mobile video capture, photography and laser scanning systems.
The new technology mentioned sofar represents an evolution of existing technology. But the real revolution in mapping will come from the move from 2D to 3D and improvements in data streaming technologies. As discussed at the beginning of this article, maps are already changing with aerial photography giving a more realistic view of what is on the ground. Now Google and Bing are fighting to capture public interest in 3D mapping and big players in entertainment are driving forward with ever more sophisticated innovations in Virtual Reality. Even some Sat Navs now offer a 3D view.
Extensive 3D modelling is already happening using vertical and oblique aerial photos. Extensive street level photos meanwhile adds ground level 360 degree imagery into the mix and with ground level laser scanning and video capture are building street level ‘asset’ databases . This technology called Augmented Reality is already appearing on the iPhone and other large screen smartphones or PDA’s. It will not be long before you will be able to zoom in from space onto any street location in the world and view everything from that spot on the ground, and even enter public buildings, such as shops and libraries.
This is where we enter the world of the ‘Metaverse’. This is a virtual world where you can re-create the real world on screen and visit directly from your PC or phone. You can already download user-generated layers for Google Earth 3D that provide locations of landmarks, houses and walking trails and through Google’s free 3D modelling software (SketchUp) users can create visualisations. Perhaps your Avatar (a representation of yourself typically as a 3D model as used in computer games) will be able to visit the inside of the apartment for rent or home for sale, or the shoe department in the department store, or your perhaps your local supermarket to do your weekly shop.
Aerial surveying will continue to have a significant input into this new generation of maps, and we will see an increase in the numbers of surveys taking place for a wide range of applications; cartographic, environmental, natural disaster, humanitarian, and of course this new virtual world we are all about to enter.
