Commercial unmanned aerial systems (UAS) available to consumers
vary greatly in size and capability. Purpose built systems are offered by
producers for a variety of missions. For aerial photography and cinematography,
Dà-Jiāng Innovations Science and Technology Co., Ltd (DJI) has established itself
as an industry leader in small UAS (sUAS). The technology firm offers a range
of options for aerial camera drones that span from those appropriate for
amateur users to professionals. One of their most capable and well-rounded
platforms is the Inspire 2 filmmaking drone.
The Inspire 2 (see Figure 1) is an sUAS designed with
professional photography and cinematography in mind. The aircraft design form
is an electrically powered quadcopter. The drone is satellite navigation
enabled, has an obstacle avoidance system, and can function with a high degree
of autonomy or can be configured to use two remote controls; one pilot and one
camera operator. At first glance, the system looks very similar to the previous
iteration. There have been many changes, however, that have contributed to
evolve it to a more capable and safe aerial cinematography sUAS.
Figure 1. DJI Inspire 2 with Zenmuse
X5S Camera image as published on https://www.dji.com/inspire-2/info
Perhaps the most innovative advances on the platform lie in the
cameras and data storage system. The drone incorporates a first-person view
(FPV) camera for the streaming video to the pilot, as well as a customizable
primary camera payload. The highest resolution camera compatible with the
platform is the Zenmuse X7 (see Figure 2). The camera features a Super 35 sensor,
and is able to shoot 6K video and 24-megapixel still photography (Zenmuse X7,
2017). Its 24-megapixel sensor is rated at 14 stops of dynamic range and can
collect continuous RAW images in burst shooting at a rate of 20 frames per
second (Zenmuse X7, 2017). The lenses can be changed to meet the photography or
cinematography needs. DJI offers four specifically designed for the image
sensor; 16mm F2.8, 24mm F2.8, 35mm F2.8, and 50mm F2.8 (Zenmuse X7, 2017).
Figure 2. DJI Zenmuse X7 Camera image
as published on http://www.dji.com/zenmuse-x7/info#specs
To manage the high-resolution imagery, the camera integrates with
the CineCore 2.1 Image Processing System (Esulto, 2017). The system records in
two formats; CinemaDNG and Apple ProRes (Zenmuse X7, 2017). Both formats allow
for compression of very high-resolution image files. Though not as condensed as
other formats, the reason for using them is the ability to maintain a high
dynamic range and overall better image quality. The drawback is a very notable increase
in file size.
The increased file size is an issue that had to be addressed for the
Inspire 2. Data storage is a challenge with the size of files for
high-resolution imagery. The aircraft does use the industry standard of
Micro-SD cards, but for greater demand, DJI has introduced the use of optional solid-state
drives (SSD) (Inspire 2, 2017). The use of a SSD, CINESSD as it is called by
DJI, allows operators to collect video footage at the camera’s highest
resolution. DJI offers CINESSD drives in sizes ranges from 120GB to 480GB.
Filming video the highest quality video requires a generous amount of storage
space. For this application, quality takes precedence over compression.
Until another data format is developed that will allow for
high-resolution imagery to be compressed without degradation of quality, the
current alternatives should be expected to remain the standard. We have seen
image processing on platforms move from the camera to the vehicle, allowing for
increasingly capable cameras to be fitted to the gimbal mount and yet maintain
smaller form factor. I see the most notable changes in the near future to this
platform to be in data storage. The CINESSD is a step in the right direction,
but even the largest drive available has its limitation when shooting in the
highest resolution. I recommend DJI continue to develop storage technology to
meet the demands of today’s high-end camera systems. This may be achievable
with next generation SSD technology like that used in Intel and Micron
Technology’s 3D XPoint.
