Drone Surveys: HexCam even more accurate with P4RTK

You may not realise it but you’ve probably seen a surveyor at work. You might have paid for a building surveyor to inspect a house you’re hoping to buy whilst hoping they don’t find any dream shattering cracks in the walls.  Or you may have seen surveyors walking around fields, on building sites or next to the road holding a long pole with what looks like a frisbee on the top. Surveying has traditionally been a ground based activity with a lot of legwork, or has involved climbing up scaffolding or looking out of cherry pickers to inspect hard to reach areas such as rooftops.

Drones are already reducing the risks to surveyors and other trades working at height by essentially acting as remotely controlled flying tripods carrying high resolution cameras. High quality video and still images can be beamed back to a surveyor standing safely at ground level and can also be carefully reviewed offline to see if any repairs or a more targeted close-up inspection are needed.

Drone images, captured in the right way and with the right equipment, can now be used for something far smarter. Take enough overlapping images from the right height and the right angles, and powerful software can now be used to produce high quality 3D models called “point clouds” which in turn can be used to generate surveying drawings. How does this happen? Each photo taken by the drone has a ‘geolocation’ (GPS coordinates and height above the ground) hidden within the file and the software uses this information to help locate thousands of points within each image to build up the 3D picture.

The problem with ‘standard GPS’ used in things like smartphones, sat-navs and in most drones, is that it’s not particularly accurate. Fixed locations can appear to wander from one day to the next by up to ten meters and that’s no good for surveyors used to working to sub-centimeter accuracy. One solution is to set out lots of ‘Ground Control Points’ or ‘GCPs’ and locate these precisely using very accurate and expensive surveying equipment. These points then appear in the photos and the software, as it knows their exact surveyed position, will ‘tie’ everything to the GCPs dramatically improving the accuracy of the 3D model. But this still relies on someone doing lots of leg work setting out and measuring GCPs, and the drone’s position (and hence each photo’s geolocation) is still controlled using standard GPS.

So how is expensive surveying equipment able to fix a point on the ground so accurately? Surveyors use a positioning system known as ‘RTK’ or  ‘Real Time Kinetic’. It takes the standard ‘wandering’ GPS signals from multiple satellites, monitors them over time and, using some very clever algorithms, works out the real accurate position. Until now, putting such RTK positioning into drones has been extremely expensive but recent developments in drone technology mean that we can now access high accuracy RTK positioning at much more affordable prices and using much smaller drones.

HexCam can now survey large areas to the same accuracy as traditional ground-based RTK equipment with only a minimal need for Ground Control Points. Site survey times can be cut dramatically and there’s no longer a need to stick that pole in the ground every 10 meters. In fact the drone effectively gives a reading every few centimeters.

As an example, HexCam recently surveyed a 300 hectare site using RTK drone technology.  Traditional surveying methods would have taken approximately 20 days. With the RTK drone,  we captured the data within 2 days, confident in the knowledge that the results were accurate to the same standard.

Drone usage for surveying also removes the need to trudge or drive over rough, environmentally sensitive or perhaps even dangerous terrain, making affordable surveying possible in these tricky environments.  

If you’d like to know more about how RTK positioning helps us to provide accurate drone-based surveying then please contact info@hexcam.co.uk or call us on 01603 327676.

MIPIM 2019: In Cannes with KingFisher APS

March is just around the corner and with it comes the 30th edition of MIPIM in Cannes, France. We are teaming up with KingFisher APS at this world leading property event.

MIPIM is a four day event for the international property market, attended by industry influencers. The property market is facing some challenges in the coming years with growing populations and the growing need for smart cities. Technology is emerging faster than ever and solutions for sustainable growth is high on the agenda. This annual event attracts 26,000 participants from 100 countries to network, share knowledge and come to learn from each other.

KingFisher APS is a leading commercial drone operator, based in London, with a wealth of experience in the property market. Drones offer a safe solution to gather accurate information in the property sector, with very low carbon emissions.

If you are attending MIPIM 2019, we would like to hear from you. Let’s talk about how we can work together to build our future together.

4 Considerations for flying drones in Winter

Flying drones throughout the winter is a necessity to maximise available time for ongoing surveys. Often, conditions in the winter can be perfect for surveying but there are some issues that you should be aware of when flying yourself or hiring in an operator. So here are our top 4 winter drone considerations.

1)      Batteries
The lithium polymer batteries in drones do not cope well with cold conditions. Under some circumstances you can lose 30-50% of your flight time. Generally, batteries need to be kept at least 20oC to function effectively. The cold can also have an impact on the battery life of ground equipment as well. Some types of drone will not allow you to take off if the battery temperatures are too low, but others will allow you to take off, but potentially the drone could fail if power demand increases.

2) Light
Aside from the obvious lack of daylight hours in the winter, the winter sun is much lower even at midday. As a result, working can be more difficult due to the fact that the sun can be low in your eyeline when flying. Often the ground lighting in winter can be an issue, with relatively bright skies and darker ground leading to issues with the camera coping with contrast. Particularly when surveying in the winter for mapping and modelling, harsh shadows can cause very dark areas and loss of detail in images.

3) Fingers
Generally, when we are outside in the winter we move around a lot and wear gloves to keep warm. When flying a drone we tend to stand very still and hands are relatively exposed. In terms of health and safety, it’s really important to be aware of how cold you are getting and to take breaks regularly to warm up and ensure your hands are working properly!

4) Condensation
When moving drones between warmer and colder environments it is really important to acclimatise the camera. Even at different heights the air temperature and humidity can be different. In an early creative wind turbine shoot, the drone got very cold on the ground and, when it got to about 30m up, the lens instantly fogged as the air higher up was a bit warmer. You may also get a lot of condensation on your kit when you get back indoors.



"It's time for sensible discussions" - drone incidents at Gatwick and Heathrow Airport

"Is the car inherently evil?”

In the first decade of the 20th century there were no stop signs, warning signs, traffic lights, traffic cops, driver's education, lane lines, street lighting, brake lights, driver's licenses or posted speed limits. Our current method of making a left turn [USA] was not known, and drinking-and-driving was not considered a serious crime.

There was little understanding of speed. A driver training bulletin called "Sportsmanlike Driving" had to explain velocity and centrifugal force and why when drivers took corners at high speed their cars skidded or sometimes "turned turtle" (flipped over). 

Politicians, police and judges debated how to control them: What was the law of the road, and who was guilty or innocent in cases of lawsuit and litigation?"(ref: https://tinyurl.com/y9wl7c79)

Sound familiar? So... we're here again.

It is the early days of exponential growth of a new technology, people are a little bit scared of unmanned aircraft; existing legislation and infrastructure is struggling to keep up with the pace of change and today it appears that someone has maliciously used that technology to cause major disruption at Gatwick Airport, UK. Myself and a number of my colleagues who have been living and breathing drones for a few years now have been called upon to offer comment in the media.

Why aren't the geofences working? Why can't the drones be shot down? How are they being controlled? Should drones be banned? Should we increase legislation?

Those are pretty much the questions we have been asked all day in varying tones of consternation and frustration.

Let me first say how sorry I feel for all the people caught up in the delays and inconvenience of today. Personally, I feel that Gatwick have responded totally appropriately and it is better to have people delayed and inconvenienced than to have an incident resulting in injury or death.

There are going to be a lot of learning points to take away from this situation. As an industry body we have been warning for 5 years or more that there is the potential for drones to be misused, as can any useful technology. I sat in a conference in 2013 where I explained to key stakeholders how I could potentially do exactly what has been done today, so it doesn't surprise me that it has happened, I am just very thankful that it has actually had a relatively benign outcome that will hopefully get people talking about prevention.

Unfortunately, the prevention is the difficult part at the moment. When open source technology is used, that operates on readily available frequencies, it is very easy to bypass both technological and physical barriers. Nets, birds of prey, frequency jammers etc. are not in themselves going to stop a malicious pilot until it is far too late. It is going to take the defence mechanisms, plus intelligence and education, to minimise the risk of a repetition and, at the end of the day, it may not be possible to stop it.

Geofencing is vulnerable as it relies on software respecting the geofence. All a geofence is is the equivalent of a polite notice saying "please don't fly here", if a drone says "no" or doesn't read the sign there is nothing that can be done.

Physical deterrents require that deterrent to be in the right place, at the right time. If something can fire a net, a drone can fly higher. Frequency jammers are effective up to a point, but there are ways around that.

Legislation is helpful, where people are willing to follow it. But if people say no then what can you do?

When it comes down to it, this isn't a drone issue. Drones are VERY useful; we do a lot of good work with them that either can't be done by other methods or reduces costs or improves human safety. We inspect structures, we map, we model, we create beautiful images. We have done so for the last six years and we do it well.

This is a human issue. A human has used a drone to deliberately disrupt in the same way we use drones to deliberately improve. The same can be said of almost every human innovation since the sharpened stick. Except possibly the Rubik's cube, but I bet if I dig deep enough into the internet I can find someone who has managed to misuse one.

Should we ban drones? Of course not. They are a useful tool. Should we legislate, educate and continue to innovate? Of course! It is what we do. Our instructors have trained thousands of pilots over the last five years. We hear great stories of what they are up to almost every day and I am continuously impressed by the new ideas that I see on an almost daily basis when drones are used properly as part of toolboxes and processes.

The drone industry is now shifting. The drones are not really much more difficult to use than a drill or a DSLR. A "drone operator" as a job in the future is about as likely as "hammer operator" is now, the drone is simply becoming part of the wider toolbox that different industries have open to them.

It is important that they are used properly in the context of the industries they are applied in. It is obvious, over time, that they will become even more automated and there will be further moves towards autonomy.

But all the time people still need educating and enthusing on the use of drones, we'll be here at The Aerial Academy to assist, and all the time pilots are needed to provide skills in data acquisition and post-processing, the team at HexCam will be happy to help.

I hope that the situation at Gatwick is soon resolved and that the people responsible are appropriately prosecuted. I hope that this will lead to sensible discussions on how drone technology can be appropriately legislated and risks mitigated moving forwards. And I look forward to continuing to be involved in this great emerging sector.

That's it... two-pence worth. If you want more I'll need another 4p please. It is nearly double-time for Christmas after all.