True Digital Orthos and 3-D City Models

TopoSys GmbH, has developed a line of turnkey, LiDAR/Imaging systems and software that provides a fast, cost-effective solution to gather, process and generate final deliverables such as true digital orthos and digital 3D city models.

Unlike with conventional ortho-images, true ortho-images correctly project vertical walls of buildings, and rooflines are not offset. To accomplish this, image data is blended with the elevation model through simultaneous acquisition by the TopoSys LiDAR/Imaging systems. This capacity to synchronously acquire and record digital image data in four spectral channels, utilizing high-point-density LiDAR, eliminates leaning edges and allows all captured objects to be computed in their proper positions.

TopoSys systems are made up of a family of three sensor systems—Falcon III, Harrier 56/G3, and Harrier 24—all powered by TopPIT processing software.

The Falcon III utilizes a unique, technologically advanced fiber-optic linear array LiDAR sensor with an effective measurement rate of 125kHz and an integrated four-channel (R, G, B, NIR) optical line scanner, providing the capability to simultaneously acquire high-resolution multi-spectral imagery, plus elevation data.

Harrier 56/G3 represents the leading edge in LiDAR scanning and digital-image acquisition. Full-waveform echo digitization and a 200kHz pulse-rate Riegl LMSQ560 Laser scanner, combined with a calibrated 39M-pixel camera. Harrier 24 is an optimized, entry-level system for helicopter-based mapping that combines a calibrated 39M-pixel camera with a low-cost 10kHz Laser.

With achievable point densities from between ten to forty points per square meter, plus overlapping measurements and a consistent, specific scan pattern, the precise classification of objects such as buildings, railways, power line cables and other structures becomes routine.