1. DEPARTMENT OF GEOMATIC ENGINEERING The LANDMAP project for the Automated Creation and Validation of multi-resolution orthorectified satellite image products and a 1 DEM of the British Isles from ERS tandem SAR interferometry Landmap: creation of base map data from space Kamie Kitmitto MIMAS, Manchester Computing, UK Jan-Peter Muller, Alec Walker, Jeremy Morley, Joel Barnes, Ryan Keenan, Paul Cross, Ian Dowman, Karl Mitchell, Sanjay Rana University College London, UK Kumar Chugani Selektra Limited Andy Smith Phoenix Systems, Kingston-upon-Thames, UK Neil Quarmby IS Ltd. http://www.landmap.ac.uk

2. DEPARTMENT OF GEOMATIC ENGINEERING Overview LANDMAP objectives Context UK national archive of satellite data for education LANDMAP deliverables GIS for optimal scene selection & GPS QC LANDMAP IfSAR-DEM production system Accuracy assessment of IfSAR-DEM Status and future prospects

3. DEPARTMENT OF GEOMATIC ENGINEERING LANDMAP Objectives Creation of a set of base image maps of the British Isles through orthorectification of the national Higher Education satellite archive, current and future ERS Tandem multi-pass SAR interferometry to create –3rd party royalty free 1 (25m) DEM to be used for orthorectification –Orthorectified SAR products to be used as a base map for LANDSAT & SPOT geocoding All processing to be fully automated and independent of ANY external copyrighted data-sets so that it can be applied anywhere in future using any satellite data –dead reckoning : no need for Ground Control –Use of GLOBE-DEM to provide phase flattening Development of national IfSAR processing facilities for UK Higher Education for large-scale projects

4. DEPARTMENT OF GEOMATIC ENGINEERING Example LANDMAP multi-sensor tiepointing

5. DEPARTMENT OF GEOMATIC ENGINEERING Context Topography required both for georadiometric correction of satellite data and scientific applications such as improving hydrological modelling ERS Tandem IfSAR could be used to create global topography at grid-spacings down to 1 (30m) almost everywhere except tropical forests & water bodies ERS Tandem IfSAR can also be used to densify existing 30 (~1km) and future 3 SRTM DEMs and with multiple passes can achieve accuracies up to 1m Zrms ERS Tandem IfSAR-DEMs can be used to fill in gaps from SRTM 3 (~100m) above 60º and improve accuracy Many applications require changes in the land surface topography (e.g. aviation, telecomms) which differential IfSAR could provide using IfSAR-DEMs

6. DEPARTMENT OF GEOMATIC ENGINEERING UK National Archive of Satellite Data for Education National coverage of remote sensing satellite data acquired to support teaching, learning and research across all sectors of Higher Education Existing level 1 SPOT panchromatic (182 scenes) and LANDSAT- 5 data (35 scenes) from 1980s currently not used by non-RS specialists due to difficulty in relating these to other data with geographical co-ordinates Acquisition of 1999/2000 archive of LANDSAT-7 scenes to relate to census dataLANDSAT-7 ESA kindly agreed to acquire additional ERS Tandem ascending (nigh time) coverage during Autumn 1999 to fill gaps & to complement LANDSAT-7 data Raw SAR data provided through InfoTerra from DERA Space.

7. DEPARTMENT OF GEOMATIC ENGINEERING LANDMAP Deliverables Output datasets (satellite data in both strip and mosaic formats) –1 (30m) Digital Elevation Model product (WGS84 and GB National Grid) –Kinematic GPS profiles for quality assessment of DEM and geocoded products –Orthorectified archive of ERS-SAR amplitude and phase coherence data-strips –Orthorectified archive of LANDSAT 30m & 15 m PAN and SPOT 10m data –Mosaic of orthorectified IfSAR, LANDSAT & SPOT products –Multi-sensor satellite data in various fused formats Output Services –Quality Assurance of geometric properties all of the above products –GIS layer masks and cut-lines showing origin of DEMand image products –Web based training materials on use of ERS-IfSAR data for mapping and interferometry –Integrated set of software tools, a guide to best working practice, and a streamlined work flow for the processing of remote sensing satellite data –End of project workshop/seminar (RSPS Conference 12-14 September 2001 DTI Conference Centre, London) National automated System/Procedures and resources on MIMAS for IfSAR-DEM and orthorectification of satellite imagery using ortho IfSAR phase coherence as base map

8. DEPARTMENT OF GEOMATIC ENGINEERING GIS for Optimal Scene selection and GPS quality control data Planning ERS tandem data selection needed to optimise –the longest possible strip length (data acquisition time period) –same season with a clear preference on Autumn/Winter (leaf-off) –best possible IfSAR imaging geometry determined by the perpendicular inter- antennae/spacecraft distance –Limited budget for ERS data acquisitions –3 phases/passes for DEM: descending, ascending, gap-fillers DESCW metadata ingested into ARC/INFO GIS GIS spatial handling facilities employed to select best strip data for subsequent processing GIS employed with 3rd party digital road data to select optimal routes for kinematic GPS transects for IfSAR-DEM quality assessment as well as planimetric quality assessment of satellite orthoimage products

9. DEPARTMENT OF GEOMATIC ENGINEERING ERS Tandem data selection for 4 Passes (daytime, night-time, gap-fillers) to maximise coverage & imaging geometry 1st pass coverage2nd pass coverage

10. DEPARTMENT OF GEOMATIC ENGINEERING ERS Tandem data selection for 4 Passes (daytime, night-time, gap-fillers) to maximise coverage & imaging geometry 3rd pass coverage4th pass coverage

11. DEPARTMENT OF GEOMATIC ENGINEERING GIS was also employed to select optimal routes for Kinematic GPS profiling to assess the quality of Individual strips, their overlap, the final merged results from the 3 phases and orthorectification

12. DEPARTMENT OF GEOMATIC ENGINEERING LANDMAP IfSAR-DEM production system LANDMAP IfSAR-DEM processing uses Phoenix Systems PulSAR for SAR focussing and InSAR Toolkit for interferogram/phase coherence for ERS SAR strips Strip processing developed to minimise number of individual scenes to be processed (e.g. 82 to 13 for 1st pass) Precision orbital elements (PRCs) used from D-PAF Coarse 30 (1km) DEM from CEOS-GLOBE and DTED0 used to correct for inaccuracies in PRCs & to enable dead reckoning without control points Low phase coherence mask used to eliminate water features which cause problems for phase unwrapping All output products in geoTIFF format for subsequent use in GIS, standard image display and processing software

13. DEPARTMENT OF GEOMATIC ENGINEERING GLOBE-DEM import DEM reprojection PulSAR focusing Orbit & registration analysis SAR image co-registration Master | Slave SAR ortho & phase adjust Interferogram/coherence GLOBE-DEM (SAR co-ords.) Phase unwrapping Height interpret+ortho Geocode IfSAR DEM On MIMAS Irwell each 5-scene strip takes 3-7 days to process, creating 30GB of data, employing 5% of the CPUs, 0.9gb of RAM. Each Pass creates around 500gb of data products, all of which are backed up onto DLT4000

14. DEPARTMENT OF GEOMATIC ENGINEERING LANDMAP 1st Pass DEM Pseudocolour IfSAR DEM at 30 (Descending ERS data) 1st Pass gaps filled by GLOBE-DEM

15. DEPARTMENT OF GEOMATIC ENGINEERING First-pass Phase Coherence N.B. Large areas With PC>50% Lower phase Coherence over Scotland & Wales. No apparent relationship to height difference with OS® PANORAMA®

16. DEPARTMENT OF GEOMATIC ENGINEERING Accuracy assessment of IfSAR-DEM Assessment of IfSAR-DEM accuracy –3rd party DEMs such as the OS® PANORAMA 50m DTM –comparison of hydrological networks derived from IfSAR-DEM cf. existing blue line (e.g. IH MLF ) Assessment of planimetric and elevation accuracy through 2 special dedicated 2 week campaigns to collect kinematic GPS around British Isles ITE Monks Wood land cover map is also being used for assessment of accuracy EA laser altimetric DEMs being employed for detailed understanding of what level the heights represent in canopy Best accuracy appears to be around 2.5m Zrmse vs. IH-OS 50m DEM (further details in Walker, Muller, Naden, IGARSS99) but more typically 8-14m Zrmse vs. kGPS

17. DEPARTMENT OF GEOMATIC ENGINEERING Factors affecting Accuracy of IfSAR-DEM Surface level for scattering centres which are often assumed as the top of observable canopy affected by tree cover, depth of penetration, tower obstacles Atmospheric effects due to time delay effects from water vapour variability Phase unwrapping artefacts Planimetric accuracy due to PRC and timing errors Artefacts in the GLOBE DEM which cannot be corrected by ERS-1 RA as there are insufficient density of such points in the UK Phase coherence effects due to land cover and local surface wind/water conditions (little, if any evidence found for correlation with height differences)

18. DEPARTMENT OF GEOMATIC ENGINEERING Accuracy assessment of IfSAR-DEM : Kinematic GPS showing the effects of canopy tops cf. kGPS road surface

19. DEPARTMENT OF GEOMATIC ENGINEERING Accuracy assessment of IfSAR-DEM : Atmospheric artefacts detected by comparison with OS® PANORAMA N.B. Severe artefacts in Eastern Scotland but very few other regions. These will be removed using multipass fusion. Red-PC G/B- IfSAR-OS IfSAR-OS

20. DEPARTMENT OF GEOMATIC ENGINEERING Accuracy assessment of IfSAR-DEM : Phase unwrapping artefacts MCFU (original) InSAR (original) MCFU/InSAR N.B. MCFU/InSAR produces tile artefacts due to the local adjustment wrt GLOBE which will be eliminated using multi-pass combinations

21. DEPARTMENT OF GEOMATIC ENGINEERING IfSAR DEM - KGPS

22. DEPARTMENT OF GEOMATIC ENGINEERING Panorama DEM - KGPS

23. DEPARTMENT OF GEOMATIC ENGINEERING DTED DEM - KGPS

24. DEPARTMENT OF GEOMATIC ENGINEERING IfSAR/LIDAR Comparison

25. DEPARTMENT OF GEOMATIC ENGINEERING Planimetric accuracy OSCAR road lines, 1:50,000 map derived (Crown Copyright 1999) in Green, kGPS trails in Blue superimposed on SAR amplitude image

26. DEPARTMENT OF GEOMATIC ENGINEERING N.B. Most areas with height differences 9m and much of the low lying areas with Z1m DEM as of 6 th of March 2001. Excellent results for IfSAR-OS® height differences where there are no atmospheric effects or problems with dropped lines

27. DEPARTMENT OF GEOMATIC ENGINEERING Status and Future Prospects Final DEM completed by 3rd April 2001 Orthoimage creation will now proceed with ERS Imagery LANDSAT 5 & 7 and SPOT will follow - May 2001 Public Web page to introduce techniques and to deliver DEMs & metadata using a point-and-click interface based on ArcIMS and OpenGIS Web Mapping testbed under development, due by Q3/ 2001 Final LANDMAP products due for release Q3/ 2001 URL: http://www.landmap.ac.ukhttp://www.landmap.ac.uk