Abstract
Abstract. This paper introduces a system for real-time generation of digital surface models (DSM) based on an optical multi-camera system flown on board of a manned airplane or helicopter. The system consists of high end consumer cameras, GNSS/IMU system, and on-board computers for real-time data processing. Usually, generation of digital surface models from aerial imagery is done in an off-line process, leading to delayed availability of height data. The proposed system processes data in real time on board of the aircraft and downlinks the generated DSM to a ground station. This paper evaluates the GNSS/IMU on-line solution quality and its impact on dense stereo matching. The proposed real time sliding window based bundle adjustment significantly improves image orientations and DSM quality, allowing generation of detailed digital surface models with a resolution of 2*GSD. Experiments using two flight patterns are conducted over the city of Landsberg and the resulting DSMs are evaluated against a LiDAR generated reference point cloud. The online bundle adjustment is shown to minimize the effect of systematic GNSS/IMU offsets while adding only a limited delay.
Highlights
Generation of Digital Elevation Models (DEM) from airborne imagery is a one of the basic photogrammetric tasks, and the basis for many applications
The conventional digital surface models (DSM) generation process is divided into image acquisition, for example using UAVs, planes, helicopters or satellites, where images are recorded using optical camera systems
In this work we present a workflow that is capable of generating digital elevation models in real time, synchronized to the image capture, and outputting a steady stream of height data with a constant latency
Summary
Generation of Digital Elevation Models (DEM) from airborne imagery is a one of the basic photogrammetric tasks, and the basis for many applications. The conventional DSM generation process is divided into image acquisition, for example using UAVs, planes, helicopters or satellites, where images are recorded using optical camera systems. Later, these images are transferred via a data link or hard drives to a processing center, where the image and sensor data is processed using several steps, mainly consisting of image orientation, dense image matching and post-processing. In this work we present a workflow that is capable of generating digital elevation models in real time, synchronized to the image capture, and outputting a steady stream of height data with a constant latency. The proposed method was validated against LiDAR ground truth data on two image sets acquired with the 4K sensor system on a helicopter (see section 3)
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