The interferometric utilization of Synthetic Aperture Radar data from L-band and C-band has an important role for the monitoring of land surface deformations like former evaluations have proven [1]. Meanwhile several multi-sensor ground-stations are available, equipped with bi-directional artificial corner-reflectors (CR) and permanent GNSS stations, attached to fine leveling baselines. The long wavelength of L-band SAR missions like ALOS-2 (λ = 22.9 cm) provides highly coherent interferograms, but here large-sized CR are required e.g. for absolute motion calibration. SAR missions with shorter wavelengths, like the C-band onboard the Sentinel-1 mission (λ = 5.6 cm) provide, in general, less coherent interferograms, but a smaller CR size is sufficient. In order to assess the capabilities of L- and C-band SAR data the impulse response function will be calculated at corner-reflector sites and the coherence will be estimated in rural areas of the Saar test site. The test site is located in the Saar-Lorraine coal basin at the French-German border, a nowadays post-mining district with highly urbanized settlements as well as large stretches of forested and rural areas. The area is characterized by century long active deep mining – mainly for hard coal – including extensive groundwater management measures. Here, the active coal mining started in the 18th century and ended in 2006 (Lorraine) and 2012 (Saar) [2]. Meanwhile some of the underground mines got progressively flooded. As a consequence surface uplift occurred and is expected to be ongoing in the near future [3]. For a 12 by 14 km area in the Saar district dense and highly accurate leveling campaigns have been performed bi-annually since 2013. Thus, besides good knowledge of subsurface geology and mining activities also precise in-situ measurements of the ground motion are available. The recent and ongoing surface deformations will be monitored using multiple methods including a network of CR at multi-sensor ground stations [4] and publicly accessible Persistent Scatterer Interferometry datasets from the Sentinel-1 based Ground Motion Service Germany [5]. In late 2020 first ALOS-2 acquisitions of the Saar area from the ESA-JAXA cooperation were made available to the authors. The ALOS-2 data are evaluated and placed in relation to Sentinel-1 acquisitions. Finally, an outlook on the possible complementary use of geodetic and C- and L-band data in the Saar district as well as for other mining areas in Germany is given. [1] Wegmueller et al. 2005: Monitoring of mining induced surface deformation using L-band SAR interferometry. IGARSS 2005; DOI: 10.1109/IGARSS.2005.1526447 [2] Corbel et al. 2017: Coal mine flooding in the Lorraine-Saar basin: experience from the French mines. IMWA 2017. https://www.imwa.info/docs/imwa_2017/IMWA2017_Corbel_161.pdf [3] Heitfeld-Schetelig 2016: Gutachten zu den Bodenbewegungen im Rahmen des stufenweisen Grubenwasseranstiegs in den Wasserprovinzen Reden und Duhamel. http://www.bid.rag.de/bid/PDFs/SA//GWA_Reden_Duhamel/3_IHS_Bodenbewegungen/IHS_Saar_Gelaendehebungen_WH_Reden_Duhamel_2016_04_20.pdf [4] Spreckels et al. 2020: GNSS, Nivellement und Radar – einheitliche Multisensor-Standorte als Referenzpunkte zur Überwachung von Bodenbewegungen. Geomonitoring 2020. DOI: 10.15488/9351 [5] BGR, 2021: https://bodenbewegungsdienst.bgr.de

In letzten Jahren ist das Interesse an der Radarinterferometrie fur die Bodenbewegungserfassung stark gewachsen und kommerzielle und behordliche Dienste ste-hen zur Verfugung. Das Ziel des neuen DIN-Normungsverfahrens ist es, vereinheitlichte Be-griffe, validierte Verfahren und Standards bei den Vermessungsprodukten und der Qualitats-sicherung zu etablieren und damit fachkundig und rechtssicher fur die betriebliche und be-hordliche Praxis einsetzbar zu machen. Dieser Beitrag beschreibt den Kontext der Initiative, den Stand der bisherigen Validierungen und Standardisierungen und Beispiele von aktuellen Bodenbewegungsdiensten und Corner-Reflektoren.

This paper describes the development of an Optical 3D Shaft Inspection System needed for the survey and monitoring of Water Handling Shafts in the German Ruhrgebiet. The development is part of the RAG R&D project “ABSMon”. The end of the German hard coal mining at the end of 2018 has been determined with the Steinkohlefinanzierungsgesetz (SteinkohleFinG) from 2007-12-20. About three hundred years before now the near surface hard coal mining began in the southern Ruhr Area and in our days advanced to the northern Ruhr Area with mining depth of around -1.500 meters. The mine workings are kept dry by mine water pumping. When the active mining activities will have finished a controlled Water Handling will raise and keep the mine water to levels predetermined by the Mining Authorities. A monitoring with a mobile wireline shaft survey system is needed to run the Water Handling Shafts for an enduring Water Management. At the moment only laser scanner systems are available, but also optical systems are needed to enable the near real-time inspection with 3D presentation and 3D examination during the measurement campaign. An approach is presented that uses a camera to generate high resolution and textured 3D models of mining shafts and tunnels for inspection purposes. 1 German Aerospace Center (DLR), Institute of Optical Sensor Systems, Dpt. Information Processing of Optical Systems, Rutherfordstr. 2, 12489 Berlin; E-Mail: [juergen.wohlfeil, bernhard.strackenbrock, andre.choinowski]@dIr.de 2 RAG Aktiengesellschaft, Shamrockring 1, 44623 Herne; E-Mail: [volker.spreckels, andreas.schlienkamp]@rag.de DGPF Tagungsband 24 / 2015

Since a few years, micro UAS (unmanned aerial systems) with vertical take off and landing capabilities like quadro- or octocopter are used as sensor platform for Aerophotogrammetry. Since the restricted payload of micro UAS with a total weight up of 5 kg (payload only up to 1.5 kg), these systems are often equipped with small format cameras. These cameras can be classified as amateur cameras and it is often the case, that these systems do not meet the requirements of a geometric stable camera for photogrammetric measurement purposes. However, once equipped with a suitable camera system, an UAS is an interesting alternative to expensive manned flights for small areas. The operating flight height of the above described UAS is about 50 up to 150 meters above ground level. This low flight height lead on the one hand to a very high spatial resolution of the aerial imagery. Depending on the cameras focal length and the sensor's pixel size, the ground sampling distance (GSD) is usually about 1 up to 5 cm. This high resolution is useful especially for the automatic generation of homologous tie-points, which are a precondition for the image alignment (bundle block adjustment). On the other hand, the image scale depends on the object's height and the UAV operating height. Objects like mine heaps or construction sites show high variations of the object's height. As a result, operating the UAS with a constant flying height will lead to high variations in the image scale. For some processing approaches this will lead to problems e.g. the automatic tie-point generation in stereo image pairs. As precondition to all DEM generating approaches, first of all a geometric stable camera, sharp images are essentially. Well known calibration parameters are necessary for the bundle adjustment, to control the exterior orientations. It can be shown, that a simultaneous on site camera calibration may lead to misaligned aerial images. Also, the success rate of an automatic tie-point generation differs extremely between several photogrammetric software packages. In this article, the calibration results of a suitable camera system will be shown. For a small format consumer grade camera, the authors will give the proof of ability for photogrammetric measurements purposes. This includes the results of different processing approaches for DEM generation of environments showing high object height variations.

10 years after the first introduction of a digital airborne mapping camera in the ISPRS conference 2000 in Amsterdam, several digital cameras are now available. They are well established in the market and have replaced the analogue camera. A general improvement in image quality accompanied the digital camera development. The signal-to-noise ratio and the dynamic range are significantly better than with the analogue cameras. In addition, digital cameras can be spectrally and radiometrically calibrated.The use of these cameras required a rethinking in many places though. New data products were introduced. In the recent years, some activities took place that should lead to a better understanding of the cameras and the data produced by these cameras. Several projects, like the projects of the German Society for Photogrammetry, Remote Sensing and Geoinformation (DGPF) or EuroSDR (European Spatial Data Research), were conducted to test and compare the performance of the different cameras. In this paper the current DIN (Deutsches Institut fuer Normung - German Institute for Standardization) standards will be presented.These include the standard for digital cameras, the standard for ortho rectification, the standard for classification, and the standard for pan-sharpening. In addition, standards for the derivation of elevation models, the use of Radar /SAR, and image quality are in preparation.The OGC has indicated its interest in participating that development. The OGC has already published specifications in the field of photogrammetry and remote sensing. One goal of joint future work could be to merge these formerly independent developments and the joint development of a suite of implementation specifications for photogrammetry and remote sensing.

This paper is a part of the DGPF project "Evaluation of Digital Photo grammetric Camera Systems" and encloses the analyses of the working group "Stereoplotting". The digital imagery of the analogue camera Zeiss RMK Top 15, the digital large format frame cameras Vexcel Imaging Ultra-CamX and Intergraph/ZI DMC and the combination of four mid-format cameras Quattro DigiCAM from IGI have been used for stereoplotting. The individual point measurement accuracy has been determined for all cameras and ground sampling distances. The stereo-photogrammetric measurements for ground control points and for topographic point and line measurements have been compared between the cameras and to the terrestrial ground control point coordinates. The aerial flight campaigns are strongly influenced by the current weather conditions at the flying time. For this reason an - as far as possible - impartial evaluation could only be given by the comparison of the individual point measurement accuracy or identical point measurements in the mapping results of different aerial campaigns.

In the past, the application of Persistent Scatterer Interferometry (PSI) was primarily possible in the case of slow (less than a few centimeters per year) uniform movements. In this paper, we show how PSI permits the monitoring of relatively fast (including rates up to > 50 cm/year) and nonuniform movements using TerraSAR-X repeat observations over deep-level mining. To enable this, parts of the PSI methodology were adapted to the special characteristics of the example studied. Apart from a description of the methodology used and the result achieved, error considerations and a validation of the result with in situ measurements are included.

Zusammenfassung: Während der DGPF-Jahrestagung 2008 wurde das DGPF-Projekt zur Evaluierung digitaler photogrammetrischer Kamerasysteme erstmals öffentlich in größerem Rahmen vorgestellt. Ein Jahr nach dieser Vorstellung sind die Testdaten erfasst. Die Auswerteteams haben sich gefunden, und die nach Schwerpunkten durchgeführten Auswertungen finden aktuell statt. Dieser Beitrag versucht eine zusammenfassende Darstellung der wesentlichen Projektparameter, erste Ergebnisse und Erfahrungen werden vorgestellt. Allerdings kann auf die Detailauswertungen nicht eingegangen werden. Die große Resonanz, die schon jetzt durch das Projekt hervorgerufen wurde, belegt seine Bedeutung und Relevanz für die aktuellen Arbeiten im Bereich der digitalen Photogrammetrie.

Zusammenfassung: Wahrend der DGPF-Jahrestagung 2008 wurde das DGPF-Projekt zur Evaluierung digitaler photogrammetrischer Kamerasysteme erstmals offentlich in groserem Rahmen vorgestellt. Ein Jahr nach dieser Vorstellung sind die Testdaten erfasst. Die Auswerteteams haben sich gefunden, und die nach Schwerpunkten durchgefuhrten Auswertungen finden aktuell statt. Dieser Beitrag versucht eine zusammenfassende Darstellung der wesentlichen Projektparameter, erste Ergebnisse und Erfahrungen werden vorgestellt. Allerdings kann auf die Detailauswertungen nicht eingegangen werden. Die grose Resonanz, die schon jetzt durch das Projekt hervorgerufen wurde, belegt seine Bedeutung und Relevanz fur die aktuellen Arbeiten im Bereich der digitalen Photogrammetrie.

An important objective of the Pre-Launch AO Project GEO_165 is the evaluation of TerraSAR-X time series for ground-motion monitoring. For this purpose we ordered a significant series of TerraSAR-X repeat observations in fine resolution, single polarization stripmap mode. For the selected site there is a real monitoring demand and SAR interferometry shall play an important role in the integrated monitoring concept. SAR data of other sensors (ASAR, PALSAR) are also acquired over this site offering possibilities for comparisons. The interferometric analysis is supported by ground-based measurement campaigns (leveling, realtime, static and permanent GPS) and corner reflector installation. Differential SAR interferometry (DINSAR) and Interferometric Point Target Analysis (IPTA) are used to monitor ground movements in selected parts of a German mining area.

In this contribution the geometric characteristics of a digital photogrammetric aerial camera are discussed for the generation of digital elevation models (DEM) and stereo plotting. Due to legal restrictions the German hard coal mining company RAG Aktiengesellschaft (RAG), successor of the Deutsche Steinkohle AG , is obliged to conduct a monitoring on earth surface changes caused by mining activity. To fulfil legal demands in effective manner process chains using photogrammetry, remote sensing and Geo Information Systems (GIS) have been established. Photogrammetric methods are used to generate high resolution DEMs from which - in combination with subsidence information - geometric changes to the topographic surface are deduced. For mine site areas from about 100 km² up to 200 km² DEMs have to be generated by means of digital photogrammetric stereo-workstations with a standard deviation of ±10cm for the height. This accuracy up to now could be attained with analogue wide angle cameras at an image scale of 1:4000 and 80% end lap together with a high number of ground control points.

Underground mining activities lead to ground movements at the earth surface. An area-wide monitoring and the documentation of mining induced influences are required by the mining authorities. Work done in the past confirmed a significant potential of SAR interferometric methods to contribute information to such monitoring. Nevertheless, in spite of advanced SAR interferometric processing techniques and numerous convincing results, there are general limitations to the utility of the application. For the monitoring of mining induced deformation information gaps may occur, especially in the case of high deformation rates. Another common problem of SAR interferometry is the loss of coherence in rural areas. The new generation of SAR sensors shows a significant improvement of the applicability of interferometric techniques for mining related surface deformation. The higher spatial resolution of the TerraSAR-X sensor and its shorter repeat intervals lead to easier phase unwrapping with the possibility to measure high deformation rates. Alternatively, the use of the longer L-band wavelength of ALOS PALSAR offers good possibilities in rural areas and in the case of fast surface movements. The German hard coal mining company RAG Aktiengesellschaft (RAG), in cooperation with the Clausthal University of Technology and GAMMA Remote Sensing set up the R&D project “GeoMon” to investigate the potential of the available new SAR sensors for monitoring surface deformations above an active and an abandoned mine. The results of the interferometric analysis using TerraSAR-X and ALOS PALSAR data will be presented combined with the validation of the results with comprehensive terrestrial measurements.

Due to legal restrictions, the German hard coal mining company Deutsche Steinkohle AG (DSK) is obliged to conduct a monitoring on surface changes (subsidence) caused by mining activity (e.g. topographic surface, groundwater, water, flora and fauna, soil). To fulfill legal demands and to do this effectively, process chains by use of Photogrammetry, Remote Sensing and Geo Information Systems (GIS) have been established. Photogrammetric methods are used to generate high resolution Digital Elevation Models (DEM) from which in combination with subsidence data geometric changes at the topographic surface are deduced. For mine site areas from about 100 km2 to 200 km2 DEMs have to be handled on digital photogrammetric stereo workstations with a height standard deviation of ±10cm. This accuracy up to now could be obtained with analogue wide angle cameras at an image scale of 1:4000 and 80% end lap together with a high number of ground control points (GCP). More and more digital aerial frame cameras like Intergraph DMC and Vexcel UltraCamD are available for mapping application. DSK decided to order photo flights with the Vexcel UltraCamD because only this camera is able to take images at 80% end lap with a ground sampling distance (GSD) of 10cm. A vertical accuracy of about ± 8 to 9cm should be reached. Since 2004 three digital photo flights have been made for DSK with the same camera, no. 8. In December 2004 for the stereo plotting of a site plan for a coking plant, in August 2005 a test flight covering 20 km2 has been made to evaluate the potential of color-infrared images for environmental monitoring purposes and in March 2006 an aerial photo flight for DEM generation of a mine site followed. The stereo plotting showed differences in height of about 25cm for neighbored 60% stereo models based on systematic effects in the digital aerial images. DSK noticed that usual commercial digital photogrammetric workstations were not able to handle systematic image errors determined by bundle block adjustment. The model deformations were acceptable for the horizontal coordinate components, but in the height, deformations exceeded the accuracy limit. The program DEMCOR has been generated at the Institute of Photogrammetry and Geoinformation, Leibniz University Hannover, for a posteriori correction of DEM and the program IMGEO for the resampling of the images for accurate stereo-measurements. So the full accuracy potential can be reached. This paper presents the comparison of UltraCamD and analogue RMK TOP 15 DEM as well as the systematic image errors of a DMC (photo flight Frederiksstad). The photo flights have not been made with the now available latest versions of DMC and UltraCamD processing software. In the meantime Intergraph and Vexcel modified the cameras and the data handling. The described geometric problems still exist for analogue cameras, but they are usually ignored.

In the mining context there is a specific interest in monitoring temporally non-uniform high deformation rates with high spatial gradients. In recent years land surface deformation monitoring with SAR data reached some maturity. Mainly C-band SAR data were used. Nevertheless, there remain important limitations to the availability of the interferometry based deformation information. Reasons include incomplete spatial coverage with information gaps for low coherence areas, problems in resolving high deformation gradients, and problems in resolving temporally non-uniform deformation. The objective of our contribution is to demonstrate that these limitations are significantly reduced at L-band. In vegetated areas and for fast deformations a good applicability of L-band INSAR was found.

This article investigates whether differential synthetic aperture radar (SAR) interferometry can be used to monitor land subsidence. The principle of the technique and the approach used on a specific case are presented. The high potential of differential SAR interferometry to monitor a wide range of deformation velocities ranging from fast (m/year) to slow (mm/year) was demonstrated by the generation of subsidence maps for sites in Germany, Mexico, and Italy. The SAR interferometric displacement maps are validated with available leveling data. Differential SAR interferometry is suitable for operational monitoring of land subsidence due to the accuracy of the maps produced, the extensive SAR data archive over the past 10 years, the expected continued availability of SAR data, and the maturity of the required processing techniques. A strategy for the integration of leveling, global positioning systems, and SAR data is proposed in order to achieve an accurate, rational and cost-effective monitoring.

Subsurface coal mining cause significant surface deformations. In this contribution the potential and limitations of ERS repeat-pass differential SAR interferometry for mining induced surface deformation monitoring is evaluated based on the example of the German Ruhrgebiet. ERS data in ascending and descending mode, including Tandem pairs suited to estimate the topography related phase, are used for the analysis. Especially for urban areas the technique performs well as confirmed through validation with mining information. The main limiting factor identified is temporal decorrelation of the signal which does not allow estimation of surface deformation velocities in forested and in many cases agricultural areas.

Due to legal requirements the German hard coal mining company “Deutsche Steinkohle AG” (DSK) is obliged by assessments on environmental impact to make a prognosis and to forecast influences caused by current excavations. Important data needed are “Digital Terrain Models” (DTM) which describe the topographic situation, information on biotopes and the actual land-cover. Today these data are generated by methods of analytical photogrammetry and by manual fieldwork. With regard to effectiveness and economy DSK has started to evaluate new methods of data taking and data processing by using digital photogrammetry and remote sensing techniques

Due to legal requirements the German hard coal company "Deutsche Steinkohle AG" (DSK) is obliged by assessments on environmental impact to make a prognosis and to forecast influences caused by current excavations. Important data needed are "Digital Terrain Models" (DTM) which describe the topographic situation, information on biotopes and the actual land-cover. Today these data are generated by methods of analytical photogrammetry and by manual fieldwork. With regard to effectiveness and economy DSK started to evaluate new methods of data acquisition and data processing by using digital photogrammetry and remote sensing techniques.

The mining activities of the German coal mining company Deutsche Steinkohle AG (DSK) lead to subsidence -induced large area influences e.g. to the ground water level or to watercourses. Aerial photogrammetry, and thus Digital Elevation Models (DEM) and stereo plotting of mine heaps and industrial sites, is based on the 'TP network' of the Ordnance Survey of North Rhine-Westphalia (LVA-NRW). The terrestrial survey, and thus line-levellings or site plans, generally base on the local cadastral 'AP network'. These networks contain differences of about 1 m to each other. Aerial flight campaigns with modern radar or laser sensors are based on GPS/INS data. Spaceborne satellite data will often be geocoded by using the standard DREF transformation parameters set up for Germany that lead to differences of several meters to local coordinate systems. For the combination and comparison of different DEM and other available data like terrestrial measurements, the current ground reference systems and transformation parameters have to be known. According to the recommendations of the AdV (ADV 1995) and (JAHN 2001) a common homogeneous coordinate system with standardized transformation parameters from the "European Terrestrial Reference System 1989" (ETRS89) to the "Gauß-Krüger" (GK) coordinate system (Deutsches Hauptdreiecksnetz 1990, DHDN90) was defined for the mining areas of the DSK.