Map Matching using a multi-hypothesis approach

Modern navigation systems use multi-sensor-systems for location determination in combination with GPS or DGPS. Limitations in the availability of satellites due to shadowing and multi path effects in urban areas, magnetic disturbances, wheel slips and error propagation of dead reckoning lead to loss of position information. This can be avoided by map matching which compensates for typical sensor errors. This contribution deals with methods and procedures of map matching, aiming to develop a robust procedure for autarkic rail vehicle localization. Special requirements for railway traffic have to be fulfilled: - High availability and reliability of the positioning information, precise track positioning - Support of GPS measurements in case of multi-path effects or difficult reception conditions - Use of low-cost sensor

Validierung von mobilen Stereokamerasystemen in einem 3D-Testfeld

Ziel ist die Validierung eines mobilen Stereosystems anhand vorher erfasster Objekte eines 3D-Testfeldes, welches insbesondere aus Fahrzeugen besteht. Da die Verifikation in einer quasi realen Verkehrs¬situation erfolgt, muss das 3D-Testfeld temporär immer wieder aufgebaut werden. Die 3D-Daten können mit hochgenauen terrestrischen Laserscannern gewonnen werden. Ergebnis ist eine 3D-Punktwolke. Eine Modellierung und Texturierung mit zusätzlichen Bilddaten ist möglich. Um den Aufwand zu reduzieren, sollte der Vergleich auf Basis der orientierten und georeferenzierten Punktwolken erfolgen. Für den Vergleich stehen dann mehrere Millionen 3D-Punkte zur Verfügung

Fusion von 3D-Indoor- und Outdoor-Daten am Beispiel des Luftbildkamerasystems MACS und des Innenraum-Positionierungssystems IPS.

In dem vorliegenden Beitrag wird die Fusion von Indoor- und Outdoor-Punktwolken am Beispiel des luftgestützten Kamerasystems MACS und des Innenraum-Positionierungssystems IPS dargestellt. Dazu wurden für das Bürogebäude des Deutschen Zentrums für Luft- und Raumfahrt (DLR) in Berlin-Adlershof sowohl die Außenhülle als auch die Innenräume optisch erfasst. Mit Hilfe eines kombinierten Passpunktfeldes wurden die resultierenden diskreten Raumpunkte in ein gemeinsames Koordinatensystem überführt. Die geometrische Genauigkeit des erstellten 3D-Models wurde anhand von punktuellen Messungen mit einem Laserentfernungsmessgerät validiert

Fully automated generation of accurate digital surface models with sub-meter resolution from satellite imagery

Modern pixel-wise image matching algorithms like Semi-Global Matching (SGM) are able to compute high resolution digital surface models from airborne and spaceborne stereo imagery. Although image matching itself can be performed automatically, there are prerequisites, like high geometric accuracy, which are essential for ensuring the high quality of resulting surface models. Especially for line cameras, these prerequisites currently require laborious manual interaction using standard tools, which is a growing problem due to continually increasing demand for such surface models. The tedious work includes partly or fully manual selection of tie- and/or ground control points for ensuring the required accuracy of the relative orientation of images for stereo matching. It also includes masking of large water areas that seriously reduce the quality of the results. Furthermore, a good estimate of the depth range is required, since accurate estimates can seriously reduce the processing time for stereo matching. In this paper an approach is presented that allows performing all these steps fully automated. It includes very robust and precise tie point selection, enabling the accurate calculation of the images’ relative orientation via bundle adjustment. It is also shown how water masking and elevation range estimation can be performed automatically on the base of freely available SRTM data. Extensive tests with a large number of different satellite images from QuickBird and WorldView are presented as proof of the robustness and reliability of the proposed method

In-Orbit Geometric Calibration of Firebird's Infrared Line Cameras

The German Aerospace Center (DLR) has developed and launched two small satellites (TET-1 and BIROS) as part of the FireBIRD mission. Both are capable to detect and observe fire related high temperature events (HTE) from space with infrared cameras. To enable a quick localization of the fires direct georeferencing of the images is required. Therefore the camera geometry measurements with laboratory set-up on ground have to be verified and validated using real data takes. This is achieved using ground control points (GCPs), identifiable in all spectral bands, allowing the investigations of the whole processing chain used for georeferencing. It is shown how the accuracy of direct georeferencing was significantly improved by means of in-orbit calibration using GCPs and how the workflow for processing and reprocessing was developed

Long-term Investigations of Quality and Reliability of the Video Image Detection System m3

Video image detection systems (VIDS) are increasingly being used to monitor the traffic situation. Visual systems are operated with the help of image processing, which has aroused a permanent discussion concerning the quality of such systems. Therefore, different factors influencing the quality and reliability of such systems were examined within the last years. An automatic evaluation during 24 hours a day, 7 days a week has to be carried out to make an examination as comprehensive as possible. These kinds of examinations can be carried out using the “Urban Road Research Laboratory”, which is a specialised measurement section of the German Aerospace Center (DLR) Institute for Transportation Systems. An evaluation approach of the m3 system is described in this paper

Long-term Investigations of Quality and Reliability of the Video Image Detection System m3

Video image detection systems (VIDS) are increasingly being used to monitor the traffic situation. Visual systems are operated with the help of image processing, which has aroused a permanent discussion concerning the quality of such systems. Therefore, different factors influencing the quality and reliability of such systems were examined within the last years. An automatic evaluation during 24 hours a day, 7 days a week has to be carried out to make an examination as comprehensive as possible. These kinds of examinations can be carried out using the “Urban Road Research Laboratory”, which is a specialised measurement section of the German Aerospace Center (DLR) Institute for Transportation Systems. An evaluation approach of the m3 system is described in this paper

Modular Photogrammetric Sensor Systems for Real-time Information Extraction and 3D-Applications

To enable research in the field of real-time information extraction and precise 3D reconstruction from aerial remote sensing data, a set of experimental sensor systems has been developed at the DLR Institute of Optical Sensor Systems. The Modular Airborne Camera System (MACS) stands for the concept of a highly flexible photogrammetric sensor system. It consists of a set of calibrated camera heads, a commanding unit and auxiliary measuring devices e.g. for position and orientation. The processing unit simultaneously operates up to 6 camera heads and handles the data processing, storage and output to a real-time data-downlink. The geometric flexibility is expressed by the possibility to rapidly change the geometric configuration for oblique or wide-swath imaging. Also the spectral range can be adapted, cameras recording visual, near infrared and thermal infrared light as well as hyperspectral sensors can be operated simultaneously. To be able to use a wide range of carriers a further design concept is low weight and small size. Systems have been integrated in (wing)pods (e.g. Stemme S10, Tornado), in standard aircraft and in fixed-wing as well as in multi-rotor UAVs. A high level of autonomy is reached by using a GPS-based fully automatic image acquisition. A rigid and determinable alignment of sensors, optics, position and orientation measurement systems as well as an extensive geometric and radiometric calibration is essential for the photogrammetric 3D capability of the system. It has been developed and verified in several instances over the last years. Industrial grade sensors delivering high frame rates allow very high overlaps of all sensors even at high flight velocities what qualifies MACS especially for 3D-reconstruction of oblique image flights over urban areas. An in-house developed operating software is used in all MACS sensor systems and provides images with an exact timestamp, position and orientation information to ensure an consistent photogrammetric workflow. Main fields of application of the MACS system so far have been real-time monitoring and information extraction for security applications, full 3D data acquisition for simulation purposes, especially in urban scenarios and 2,5D mapping even under extreme conditions in the Himalayas