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Departement BauVermessungsamt
Evaluation of UAV-based orthoimages for the use in cadastral mapping
H. Eisenbeiss, M. Sauerbier , Ch. Wildi
September 4, 2013
Demo at UAV-g 2011
Departement BauVermessungsamt
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Content
• Introduction
• Motivation/Restriction
• Traffic education area for children “Verkehrsgarten”
• Cemetery Oberwinterthur (City of Winterthur)
• Conclusion
Departement BauVermessungsamt
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Campus Science City Hoenggerberg, ETH Zurich; UAV-g (2011) (R-Pod)
Thanks to the organizers UAV-g 2013 in Rostock!
Departement BauVermessungsamt
City of Winterthur
Land registry office§ Geoinformatics§ Surveying
Surveying section is responsible § Cadastral surveying§ Control of construction survey
In addition we offer different kind of surveying in Winterthur§ Monitoring of construction / construction sites§ Engineering survey§ Terrain measurement …
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Departement BauVermessungsamt
Motivation§ Use of UAVs for cadastral mapping of
§ Parks§ Street sections (Planning and updating the map after construction)§ Waste disposal areas
§ Updating 3D City Models§ Main buildings in the city
§ First results about the accuracy of extraction of geometriespresented at UAV-g 2011(Manyoky et al.)
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Departement BauVermessungsamt
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Cadastral restrictions in Switzerland
Art.3 TVAV• TS1: Central business districts
• TS2: Built-up areas and construction zones
• TS3: Intensively used agricultural and forested areas
• TS4: Extensively used agricultural and forested areas
• TS5: Alpine and non-productive areas
TS2 (HXE)Lateral accuracyLand cover and single objects 10cm
Land ownership
Not exactly defined point
3.5cm
20cm
Height accuracy
Height (DTM 2m Grid)
Not exactly defined terrains
80cm
200cm
Standard Standard deviationdeviation forfor thethe zoneszones TS2 of TS2 of thethe Swiss TVAVSwiss TVAV
Departement BauVermessungsamt
Traffic education area city of Winterthur
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• Stitched image (8 images) à first overview of the area of interest
• Data acquisition was done using a UAS md4-200 from microdrones
Departement BauVermessungsamt
Traffic education area city of Winterthur• The stitched image was used in combination with the field notes for the
interpretation/ processing of the measurement data acquired with total
station and GNSS (office work)
• Image is used for the definition and visualization of the bicycle trainings
tracks
Departement BauVermessungsamt
Traffic education area city of Winterthur: Map showing infrastructure and green areas
Traffic education area city of Winterthur
Departement BauVermessungsamt
Traffic education area city of Winterthur
Traffic education area city of Winterthur: Webpage @ city of Winterthur
Departement BauVermessungsamt
Cemetery Oberwinterthur
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Departement BauVermessungsamt
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Starting position
• Request from the city gardeners of Winterthur concerning the
documentation of regenerated and renewed parks, including cemeteries
• Particularly the cemetery Oberwinterthur was an object which had to be
documented in April 2013
à Updating cadastral map and documentation of the inventory
Cemetery Oberwinterthur
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Departement BauVermessungsamt
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UAS: Falcon 8 (Ascending Technologies)
Remote Control Futaba FX-30
Falcon 8Astec Autopilot
Departement BauVermessungsamt
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Cemetery Oberwinterthur
Data acquisition
• Definition and measurement of the GCPs using GNSS
• Autonomous UAV flight
• Flying altitude 70 m
• Ground resolution 1.5 cm/Pixel
• Camera calibration on-site
• 5 minutes flight time
• Documentation of all required structures using GNSS and a total station
(Trimble )
• 3 days work (one experienced surveyer)
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Departement BauVermessungsamt
Overview GCPs
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Cemetery Oberwinterthur
Departement BauVermessungsamt
UAV image processing
§ Image orientation§ Camera calibration with iWitness§ Import of onboard IMU and GPS data à initial orientations§ Automatic tie point measurement was successful§ Manual corrections (errors at road markings, tree areas)
§ Results§ σ0= 0.23 Pixel § RMSE of GCPs less than 0.3 cm
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Cemetery Oberwinterthur
Departement BauVermessungsamt
Orthoimage generation
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§ Mosaic Pro (LPS) was used§ Existing DTM
§ Additional manual measurements at slope areas, walls and steps
§ Automated seamline generation§ Manual editing of seamlines
Cemetery Oberwinterthur
Departement BauVermessungsamt
Cemetery Oberwinterthur (results)
Departement BauVermessungsamt
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Cemetery Oberwinterthur (results)
Departement BauVermessungsamt
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Erste Ergebnisse
Cemetery Oberwinterthur
Departement BauVermessungsamt
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Results
• Automatic image orientation (mfb geoconsulting) (1/2 day)
• Orthoimage generation (1 day)
• Analysis of the orthoimage and corrections including additional manual
measurements of seed points, vectors etc. (2 days)
• Compared to vector data the main differences occur on walls, slops and
vegetation etc.
• à Accuracy in general 1-5 cm (max. 20cm)
• GNSS/Total station or UAS ?
Cemetery Oberwinterthur
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Departement BauVermessungsamt
Conclusions
§ UAV orthoimages have a great potential for § Specific restricted zones of interest in city areas§ A fast overview; web presence and commercial and
additional information for example: Documentation of a construction site
§ For cadastral mapping you need to check the completeness and correctness of the data (particularly for unknown areas)
§ Fast data acquisition
§ Commercial/open software package and knowledge are necessary
Departement BauVermessungsamt
Acknowledgments
§ IGP ETH Zurich (David Novák, Piotr Tokarczyk)§ Omnisight (Emil Siegrist)
Thank you for your attention!
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