The end-user could be a land surveyor on foot, in a vehicle or in an aircraft. “If on foot, we would equip the user with a portable computer such as PPM’s SKEYEBOOK,” Forsberg says. “This is in effect a Toshiba Toughbook with a built in NovAtel RTK receiver and antenna.
“Alternatively, for those who need a more compact unit, we can use a Tough Tablet with similar construction features. The OPTOnav software runs on that computer connected to a portable camera such as the Canon 5D and 24/50mm prime lens. The choice of lens depends very much on the range to the area of interest and required field of view.”
Forsberg Services also had to think about how the equipment would be aligned, installed and calibrated by personnel with no prior survey experience, such as aircraft engineers.
“In some ways, that has been more difficult than computing positions out of imagery,” Forsberg admits. For example, the inertial module is very particular about the orientation and offsets of peripheral equipment such as GNSS antennas from the IMU. Also, the camera and stabilized turret have to be boresighted to the INS too.
“If any part of this is wrong then the system will not achieve the required remote ground positioning accuracy of better than 50 centimetres (90%) at 500 metres,” says Forsberg. “That means offsets have to be measured to a couple of centimetres and angular alignments should generally be better than 0.025 degrees. The unique bit of this is completing the alignment within a few minutes while using actual survey imagery.”
Forsberg says the OPTOnav system had NovAtel components in it from the start. “The company relationship started with NovAtel in 1993,” he recalls, “when a fellow employee moved from a Houston-based company to NovAtel as a sales manager.
“Later, in 1996, we made an approach to NovAtel for the tracking of NASCAR and F1 vehicles for television. While this didn’t pan out as planned our company was contracted to run NovAtel Europe from about 1998. That continued until 2006. Today we are the dealer for NovAtel in the UK.”
As a result, Forsberg says, NovAtel technologies are extremely well known to his company at all levels, from engineering through to practical survey work and, of course, sales and customer support. “In particular we like their customer support. Customer Support has a reputation for speed and precision in answers.”
Forsberg says he and his team go to many shows and exhibitions, and they don’t see many real-time aerial survey systems. “What makes OPTOnav unique in that we can quickly coordinate points of interest and measure/orientate objects on the fly,” he says.
“Normally this type of data is gathered and post-processed, which can mean an extra day before the data emerges. For defense, when combined with other sensor technology, the application solves many latent problems.”
The GNSS module excels in accurate positioning, timing and inertial navigation. In particular, TerraStar-C corrections offer high levels of precision such that users can, generally speaking, achieve 3D position accuracies of 8-12 centimetres (RMS) on the camera.
And, Forsberg adds, there is a new upgraded version in the works, so this groundbreaking system is about to get even better.