Rijsdijk M-UAS in the process of juridical verification generated from manual build DEM 10. UAS in...

Unmanned Aerial Systems in the process of Juridical Verification of Cadastral Borders

UAV-g-2013, 4 Sept. 2013, Rostock

M. Rijsdijk Dutch Cadastre

W.H.M. van Hinsbergh Dutch Cadastre

W. Witteveen Dutch Cadastre

G.H.M. ten Buuren Dutch Police

G.A. Schakelaar Dutch Police

M. van Persie * NLR

G. Poppinga NLR

R. Ladiges NLR

([email protected])

UAS in the process of Juridical Verification of Cadastral Borders UAV-g-2013, Rostock

Overview

� Introduction

� Experiments

� Technical aspects

� Recent activities

� Conclusions and recommendations

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Introduction

Task of Dutch Cadaster� Maintaining an actual and complete registration of ownership,

cadastral maps and juridical borders of real estate� Verification: identification of parcel boundary by seller

and buyer� Registration: accurate measurement of boundary by

surveying

Improvement of production process� More efficient, better quality� Opportunities with small UAVs and SFM processing

� Verification on photographs (attendance easier)� Registration by photo-measurements

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Introduction

Research question� How useful are UAS in the juridical verification process of cadastral borders of

ownership at the Kadaster in The Netherlands?� Requirements

– Photographs can be used for verification of border by parties– Borders can be accurately measured with photographs (6cm)

Cooperation started� Dutch Cadaster: cadastral borders and mapping� Dutch Police: crime scene reconstruction� Dutch National Aerospace Laboratory NLR: UAS and geomatics knowledge

Experiments� Austerlitz pyramid� Nunspeet residential area� Nunspeet residential area, commercial� Hanze railway section, commercial

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Experiment Austerlitz

Austerlitz pyramid� Objective: Get acquainted with technology� Flat 180x180m area with pyramid of 30m � Jan 2012, very cold day� AscTec Falcon UAS with Panasonic L3 camera

from Police� Five flights with grids of about 100 photo’s� 24 ground markers by GNSS surveying� Afterwards processing with Bundler/PMVS2/VisualSFM

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Experiment Austerlitz

Austerlitz results� Flight planning works fine, include enough photos at borders� Short battery time due to cold weather� Enhance visibility of control points � In total 480 good quality photos with 80% overlap and 1cm detail� For processing sufficient computer power and memory are required� Lacking step from relative point cloud to referenced ortho-photo� Accuracy limited to 10cm

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Experiment Nunspeet

Nunspeet residential area� Objective: Apply technology in known Cadastral situation� Flat area of 80x200m with 20 new houses� March 2012� Ground control and boundary check points measured by

GNSS surveying, using professional markers� AscTec Falcon UAS with Panasonic L3 camera from Police� Camera calibrated with test pattern� Municipal permission arranged to fly over houses� Three flights with grids of about 100 photo’s� Processing with PhotoModeller Scanner and PhotoScan Professional

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Experiment Nunspeet

Nunspeet results� During third flight problems with platform > aborted� 105 photos covering 70% of the area, 80% overlap, 1cm detail� Control points well visible� Ortho-photo produced with PhotoScan, accuracy 5cm� 3D model lot of artefacts, limited effect on orthophoto� Thorough understanding of relevant aspects and requirements

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Experiment Nunspeet-2

Nunspeet 2� Objective: Gain experience with commercial available services� OrbitGIS hired to acquire photoset and produce ortho-photo� Same Nunspeet area to make comparison with earlier experiment� June 2012� Ground control acquired by Cadaster� Microdrone MD-4 1000 with Olympus E-P3 OGT camera� Two flights in which 360 photo’s were gathered� Processing by OrbitGIS with Orbit Strabo Photogrammetry

software

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Experiment Nunspeet-2

Nunspeet-2 results� 360 photos gathered in two flights with 80% overlap and 1cm detail� Accurate ortho-photo delivered with accuracy of 3cm maximum� Ortho-photo generated from manual build DEM

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Technical aspects

Acquisition� Platforms:

– AscTec, Microdrone, difference in endurance, payload – Special mission planning software– Enough coverage required– Stability during photo capture

� Cameras – Calibration with test pattern and software functionality– Settings for zoom level, exposure time, color balance,

autofocus� Ground control

– Visibility

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Technical aspects

Data processing� Software functionality

� Full processing chain required

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3D Extraction

Software

VisualSFM/

Bundler/PMVS2

PhotoScan

Professional

PhotoModeller

Scanner

Orbit Strabo

Photogramm.

User friendliness + ++ + ?

Settings - - + ?

Full chain - ++ + ++

availability open commercial commercial embedded

- import photo and meta - point cloud generation - DTM/DEM generation

- alignment/bundle block adjustment - mesh optimizaton - textured 3D model generation

- camera calibration - ortho-photo generation - measurements

- geo referencing - product export /GIS integration - stereo display


Technical aspects

� Geometric accuracies – Geometric measurements done in photo’s, ortho-photo, stereo model?

– Use of DEM or DTM for ortho-photo?

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Nunspeet with PhotoScan Professional absolute XYerror

(vector length) cm

XY st. deviation

cm

accuracy of 7 gcp's (as base for model)

model computation error 3.1 1.4

measurement in photo's 3.5 1.6

accuracy of 15 check points (boundaries)

measured in photo's 4.9 2.3

measured in ortho-photo 7.4 6.3


Technical aspects

� Quality of 3D point cloud– Problems with vertical walls, fences, repetitive structures, vegetation– Effect on recognition of boundaries, reliability for clients

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Recent activities

Cadaster test for Hanzeline railway section� Objective: usability of UAS in surveying process for larger (not easy

accessible) areas, comparison with traditional surveying� Agricultural area of 100 ha near Kampen, new borders� Commercially flown by MAVinci. Five flights resulting in 5500 photo’s� Processed by GEO-ID: ortho-mosaic with 2cm detail and 4cm accuracy� Measurement in ortho-photo’s and by surveying: problems to identify border

of ditches, 3D information might help� Evaluation of costs: UAS photo based 4x costs of traditional surveying (pure

measurements in photo’s 8x cheaper than measurements in terrain)

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Recent activities

Student by Dutch Police� Computation of full Austerlitz model with PhotoScanner Professional: 2cm

accuracy for check points.� Evaluation of usability/accuracy for crime scene investigation

– Shoe footprint profile– Person in hole in ground– Outdoor location with building and car

NLR� Building modelling, also based on video observations

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Conclusions and recommendations

Conclusions� Technically UAS based systems can be used for cadastral border

verification and measurement� UAV based systems in combination with SFM processing techniques can

provide ortho-mosaics with sufficient accuracy for Cadastral real estate border measurements

� The detailed ortho-mosaics are suited for involved parcel owners to verify the boundaries

� Measurement of ditch borders is difficult in ortho-photo’s, but could be supported by a 3D model / visualization

� Operationally the cadaster waits with introduction of the UAS based ortho-mosaics� Costs are too high at the moment, compared to traditional methods� Regulations for UAS operation at this moment gives still a lot of

limitations� Drones at this moment are negatively positioned by the press (privacy,

hostile)� Larger areas with single client (like railway) seem more interesting than

smaller private parcels (like new residential quarter)

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Conclusions and recommendations

� Detailed photosets offer new possibilities� 3D model fit well with trend to 3D mapping� Data acquisition has not necessarily to be done by UAS� For construction activities the same mosaic can be used by client to

indicate changed boundaries and support construction process, and cadaster to update the ownership situation

Recommendations� Evaluate possibilities of other products from detailed aerial photo’s,

like 3D point clouds, textured and stereo models for cadastral applications, including mapping

� Look at reduction of gcp collection to reduce costs

� Work out pilot in combination with construction company to investigate shared use of same data

� Further work out business case and criteria for usability

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