Go fly zone

Broadcast 

Lighter airframes, heavier payloads and longer flight-times are on the wish-lists of Unmanned Aerial Vehicle (UAV) filming practitioners but what is concentrating minds more than these incremental advances are collision avoidance and object tracking systems.

To some there is a clear need for a greater level of protection to avoid in-air accidents as the UK's skies fill with drone aviation hobbyists. To others, the automated in-flight detection and avoidance systems in development across the industry, will add fuel to an inevitable injurious, even fatal, disaster.

This is a serious issue blamed in part on a lax regulatory system that has not kept pace with skyrocketing UAV use propelled by the plummeting costs of components and the ease of buying remote controlled aircraft online.

Charges are being brought against a man who allegedly flew a drone over landmarks including the Houses of Parliament and several football stadiums without proper monitoring and at risk of collision to buildings.

“The way licences are issued there is no requirement to have any technical knowledge of how drones operate,” says Jamie Stevens, owner Helicam Media and qualified drone pilot. “There is no requirement to fly them manually without the aid of GPS. If something were to go wrong and the GPS was lost would they be able to fly it properly?”

The current standard permission from the Civil Aviation Authority (CAA) allow the UAV to be no closer than 50 metres away from any structure or person that 'isn't under your control'. Some UAV film companies can achieve special exemptions in congested areas, based around specific planning and specific safety redundancies.

Where many UAV pros tend to design and build their flying machines from scratch – brushless electric engines, propellers, airframes – many more enthusiasts and, it's claimed, commercial start-ups, are using off-the-shelf drones.

“It's like taking a weapon out of a box hoping it will operate and if there are any issues they'll just contact the manufacturer,” says Stevens. “When I am flying something over people's heads, I want to know exactly how it was put together, not hoping it is assembled right.”

He floats the idea that drones be fitted with registration barcodes so that ground-based police or air traffic officials could scan and check them using lasers.

“In the future we see a shift to airworthiness testing much the same as commercial aircraft,” says Batcam co-founder Jon Hurndall. “Only then, will regulation on distances be eased as the technology is proven and trusted.”

Several companies are developing auto-follow tracking systems. The $1m Kickstarter-funded Hexo+ claims to require no pilot or cameraman and is controlled via a 3D model of the camera’s point of view on a smartphone app. There is no avoidance system included in the first version either, although Hexo+ states that it is working on it.

“The more automated a protection system the more that can go wrong,” says Toby Pocock, MD at Skyvantage and CAA licensed drone pilot. “Our license or 'permission for aerial work' is based on a human operator. Trust me, when you put all your faith into some automated system it will almost certainly let you down.”

Other auto-follow systems include AirDog from Helico Aerospace Industries, a $500,000 Kickstarter project which is controlled by a wrist-worn wireless module at a range up to 1000 feet (300m). It is testing LIDARs, which use light sensors, ultrasonic sonars and microwave radar for its collision avoidance system.

It is also investigating how to keep its gyroscopes and accelerometers at a constant temperature because of issues caused by changing temperatures (such as filming snowboarders in sub zero cold) which it admits causes the sensors to drift and the drone to crash immediately after takeoff.

“This [type of technology] is not something we would trust or use, certainly until it was tested in many different locations and environments,” says Pocock.
Batcam's five year business plan incorporates various assumptions about how the UAV market and regulation will progress. “If, for example, collision avoidance is brought to a level where it is trustworthy, then we would expect to see an easing on distances to the public,” says Hurndall. “Imagine an overhead UAV over a football match. Even if we were flying low to the pitch, the UAV could be nimble enough to dodge a ball being kicked toward it. It's a really exciting prospect and will bring a new dimension to sports broadcasting.”

Most R&D is going into making systems lighter. Airframes are already composed of carbon fibre so the greater gains can be made by reducing the weight of batteries – which increase flight times. On average, drones flight times range between 7-15 minutes and limited battery life make the vehicles problematic for live broadcast even where regulations permit.

“For every pound we add, the less time we can fly. Better batteries is probably going to be the next breakthrough,” said Tom Hallman, president of US UAV specialist Pictorvision, at the Hollywood Professional Alliance last month last month.

CAA rules restrict operation of drones above 7kg 'without permission' over central London. “Staying under that magic 7kg weight helps speed up planning for jobs and reduces your acceptable distance from the public,” says Hurndall.

Similarly, the weight and size of onboard recorders limits flight time. “You want something that is light enough not to affect flight times significantly and small enough to mount directly onto the gimbal,” Hurndall explains. “We either record internally in the camera, or use the Atomos Shogun, which is particularly great with the Panasonic GH4 as you get an 4K 10bit output.”

Since sports broadcasters want unprecedented camera shots which follow competitors it is only a matter of time before UAVs are as much a fixture of OBs as the wire-hung spider-cams. In the US, Fox Sports has tested drones at several events including Supercross where riders were filmed in an empty stadium.

In Qatar, UAVs have been used for several years to film camel races. Dutch UAV specialist Airfilms flies drones above the track sending HD signals by RF to a car driving alongside and from there back to an OB van.

The gimball is arguably the most essential piece of drone filmmaking, stabilising the camera against the movement of the UAV. “Without these it is simply not possible to acquire super stable video,” says Pocock. “Vibrations and unwanted movement in the camera will seriously affect the shot.” 

Early models were servo operated which, according to Dean Wynton, director and UAV pilot at Aerosight, meant “a lag in the response time and were not as smooth as brushless motors.” 

Newer gimbals are packed with accelerometers and gyroscopes making “a massive difference to stability” says Wynton.

The Z15 Zenmuse, for example, is claimed by manufacturer DJI to achieve sub-pixel stabilisation. It costs £2000, a hefty price tag in the done market but nothing compared to a full-scale helicopter gimbal which costs north of £200k.

While AirDog, Hexo+ and others from UAV brand Parrot are aimed at the consumer and action sports market their designs for autonomous one-person control are impacting professional development.

David Bradley, MD at Bradley Engineering, says the firm is “not actively marketing” its Gekko remote control gimbal because the industry is dominated by lower-spec technology.

“It's a pro piece of gear for a specialist camera-operator with PTZ, focus controls and colour balance which operates on a professional radio frequency rather than on cluttered Wi-Fi bands,” he says. “Until the market matures I don't think many people would understand it.

“Auto technology is great for certain applications but the first thing any cinematographer would do is switch all the automatic functions off because they want to get a unique shot with a unique look,” he adds. 

Inexpensive pocket cameras like GoPro Hero are the go-to imagers for aerial photography but rival camera manufacturers have wised up to the demand. Arri  became the first cinema-class camera manufacturer to adapt its models for UAV use with the Alexa Mini, a version of bigger brother Alexa with a 35mm sized sensor in a compact carbon-fibre housing.

“Arri is the first step camera manufacturer to take the UAV market seriously,” says Hurndall. “Size, weight and video quality are obviously tradeoffs but critical elements for any manufacturer to consider.”

DJI's Inspire drone comes with a camera capable of recording 4K at 30fps. The gimbal can also be dis-mounted from the vehicle and used as a handheld mount (as can Bradley's Gekko).

Hurndall reveals Batcam is currently developing a system that it hopes “will revolutionise” live aerial filming. “It will be a complete system ready for professional broadcast,” he says.