Abstract
Abstract. In this paper we present the further evaluation of DLR’s modular airborne camera system MACS-Micro for small unmanned aerial vehicle (UAV). The main focus is on standardized calibration procedures and on photogrammetric workflows. The current prototype consists of an industrial grade frame imaging camera with 12 megapixel resolutions and a compact GNSS/IMU solution which are operated by an embedded computing unit (CPU). The camera was calibrated once pre-flight and several times post-flight over a period of 5 month using a three dimensional test field. The verification of the radiometric quality of the acquired images has been done under controlled static conditions and kinematic conditions testing different demosaicing methods. The validation of MACS-Micro is done by comparing a traditional photogrammetric evaluation with the workflows of Agisoft Photoscan and Pix4D Mapper. The analyses are based on an aerial survey of an urban environment using precise ground control points and acquired GNSS observations. Aerial triangulations with different configuratrions of ground control points (GCP’s) had been calculated, comparing the results of using a camera self-calibration and introducing fixed interior orientation parameters for Agisoft and Pix4D. The results are promising concerning the metric characteristics of the used camera and achieved accuracies in this test case. Further aspects have to be evaluated by further expanded test scenarios.
Highlights
INTRODUTCIONThe increasing number of small unmanned aerial vehicle (UAV)’s for survey activities led to a demand for appropriate aerial camera systems
We have proven the camera’s metric but Agisoft shows a systematic offset for the principal point and is adjusting the focal length significantly for configuration IV and V while Pix4D shows minimal deviations for the principal point with a clear outlier in configuration V (Figure 16)
Exterior orientation parameters can be obtained precisely for every image and the aerial camera system can be carried by unmanned aircrafts less 5kg maximum take-off weight (MTOW)
Summary
The increasing number of small UAV’s for survey activities led to a demand for appropriate aerial camera systems. Only a few aerial camera systems were presented for UAV’s which enable a photogrammetric image processing in a traditional manner (Martin et al, 2014; Brauchle et al, 2014). This implies to determine explicit values for the interior (IO) and exterior orientation (EO) parameters like it is common for conventional aerial mapping cameras. To verify the overall concept an aerial survey was done by using 39 ground control points, as well as precise GNSS observations Based on this data set several aerial triangulations have been calculated. Those will be compared to the results of processing the data set with the structure-from-motion based systems Agisoft Photoscan and Pix4D Mapper by using the same preconditions for IO and EO parameters
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