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GNSS: how should we measure parcels in 2010 ?

GNSS: how should we measure parcels in 2010 ?. Cozmin LUCAU, Krasimira GANISHEVA, Beata HEJMANOWSKA GeoCAP, JRC Ispra. Outline. GNSS …. overview Research objectives Field measurements Results for area measurement and point position accuracy impact of corrections: EGNOS , DGPS

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GNSS: how should we measure parcels in 2010 ?

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  1. GNSS: how should we measure parcels in 2010 ? Cozmin LUCAU, Krasimira GANISHEVA, Beata HEJMANOWSKA GeoCAP, JRC Ispra

  2. Outline • GNSS …. overview • Research objectives • Field measurements • Results for area measurement and point position accuracy • impact of corrections: EGNOS, DGPS • impact of measurement method: continuous, stop&go, vertex • Conclusions & perspectives

  3. Outline • GNSS …. overview • Research objectives • Field measurements • Results for area measurement and point position accuracy • impact of corrections: EGNOS, DGPS • impact of measurement method: continuous, stop&go, vertex • Conclusions & perspectives

  4. 1. GNSS …. overview L1 MSAS L1/L2 GPS EGNOS WAAS GLONASS GNSS 1 & 2 GAGAN GALILEO SINGLE FREQUENCY COMPASS DUAL FREQUENCY CODE CONTINUOUS CARRIER PHASE STOP&GO 300 € 10 000 € VERTEX GSM RADIO STANDALONE REAL-TIME IGS RINEX DGPS EUPOS POST-PROCESSING EUREF ????

  5. Several measurements methods Several measurement modes Several types of receivers Global Navigation Satellite Systems 1. GNSS …. overview L1 MSAS L1/L2 GPS EGNOS WAAS GLONASS GNSS 1& 2 GAGAN GALILEO SINGLE FREQUENCY COMPASS DUAL FREQUENCY CODE CONTINUOUS CARRIER PHASE STOP&GO 300 € 10 000 € VERTEX GSM RADIO STANDALONE REAL-TIME IGS RINEX DGPS EUPOS POST-PROCESSING EUREF … … …

  6. Specific needs Adapted tool 1. GNSS …. overview

  7. Area measurement GNSS 15 000 € 100 € 1. GNSS …. overview GNSS receiver complexity (price)

  8. Area measurement GNSS 1. GNSS …. overview GPS 24 (32) satellites GLONASS 18 (25) satellites GNSS receiver Measurement mode • standalone • EGNOS • DGPS • real time • post-processing GALILEO 2014 30 satellites complexity (price) 2(3) satellites +ground stations EUPOS (http://www.eupos.org/) EUREF (http://www.epncb.oma.be/) National/regional/local networks (IGN, RENAG, GPSLombardia, FLEPOS, etc.)

  9. Area measurement GNSS 1. GNSS …. overview GNSS receiver Measurement mode Measurement method • standalone • EGNOS • DGPS • real time • post-processing continuous stop&go vertex complexity (price) time / accuracy (2-3 min vs 6-7 min)

  10. Outline • GNSS …. overview • Research objectives • Field measurements • Results for area measurement and point position accuracy • impact of corrections: EGNOS, DGPS • impact of measurement method: continuous, stop&go, vertex • Conclusions & perspectives

  11. LPIS update ?? ? ? ? BUT 2. Research objectives • better understanding of GNSS to increase the performances of field measurement (area estimationANDboundary position) Correct area estimation !!! !!! Wrong boundary position !!!

  12. 2. Research objectives • better understanding of GNSS to increase the performances of field measurement (area estimationANDboundary position) • assessment of GNSS measurement mode on area measurements results • STANDALONE • EGNOS • DGPS • assessment of GNSS measurement method on area measurements results • CONTINUOUS • STOP&GO • VERTEX • assessment ofpoint position accuracy impact on area measurements results

  13. Outline • GNSS …. overview • Research objectives • Field measurements • Results for area measurement and point position accuracy • impact of corrections: EGNOS, DGPS • impact of measurement method: continuous, stop&go, vertex • Conclusions & perspectives

  14. 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions)

  15. 3. Field measurements B: regular shape, with good visibility A: regular shape, with trees mask on South part

  16. 3. Field measurements A: regular shape, with trees mask on South part

  17. B: regular shape, with good visibility 3. Field measurements

  18. C: irregular shape with good visibility 3. Field measurements

  19. 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions) Reference position of each point was measured using Trimble 5700 with Zephyr antenna in RTK mode (estimate horizontal accuracy < 1 cm) A: 8 points B: 6 points C: 28 points

  20. Pegs used for key points materialization on the field. 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions)

  21. For C field, between C5 and C6 points, no pegs installed (grass border used). 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions) For C field, vertex/stop&go method the operator decides which point needs to be measured to preserve the shape of the feature.

  22. 2005 series 2008 series 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions) • 2 GeoXT receivers: one standalone – GeoXT 1 (2005 series) and one using EGNOS corrections – GeoXT 2 (2008 series) recording data simultaneously by 2 operators ????? Same configuration EXCEPT recording mode GeoXT 1 GeoXT 2 • EGNOS corrections • logging interval: 1s • SN ratio: 39 • max PDOP: 6.0 • elevation mask: 15˚ • standalone • logging interval: 1s • SN ratio: 39 • max PDOP: 6.0 • elevation mask: 15˚

  23. 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions) • 2 GeoXT receivers: one standalone – GeoXT 1 (2005 series) and one using EGNOS corrections – GeoXT 2 (2008 series) recording data simultaneously by 2 operators • 3 sets of measurements, each set with 4 repetitions (CW and ACW) : • first continuous (A, B, C), • then Stop&Go (1 sec per point) / vertex (5 sec per point), (A, B, C) • Each set was carried out at different time period in order to cover at more large satellites conditions; Satellite configuration stable for a given set, max 35 minutes for C field (17 points for stop&go/vertex method) * - stop&go method included

  24. DGPS 1 (GeoXT 1) DGPS 2 (GeoXT 2) 4 data sets 3. Field measurements • 3 fields: A, B, C (± same area but different shapes and visibility conditions) • 2 GeoXT receivers: one standalone – GeoXT 1 (2005 series) and one using EGNOS corrections – GeoXT 2 (2008 series) recording data simultaneously by 2 operators • 3 sets of measurements, each set with 4 repetitions (CW and ACW) : • first continuous, • then Stop&Go (1 sec per point) / vertex (5 sec per point) • Each set was carried out at different time period in order to cover at more large satellites conditions; Satellite configuration stable for a given set, max 35 minutes for C field (17 points for stop&go/vertex method) • - both standalone and EGNOS corrected data were post-processed using our base station data  4 data sets standalone (GeoXT 1) EGNOS corrected (GeoXT 2)

  25. 3. Field measurements: summary • 3 fields: A, B, C • 2 GeoXT receivers: one standalone, one using EGNOS corrections recording data simultaneously* by 2 operators • 3 sets of measurements, each set with 4 repetitions (CW and ACW) : • first continuous, • then Stop&Go (1 sec per point) / vertex (5 sec per point) • 2 measured data sets (stand alone & EGNOS) 4 data sets (with post processing) • * - for continuous mode the operators are at 2-3 meters one after other and for stop&go/vertex method the recording of the data was carried out on neighbors points.

  26. Outline • GNSS …. overview • Research objectives • Field measurements • Results for area measurement and point position accuracy • impact of corrections: EGNOS, DGPS • impact of measurement method: continuous, stop&go, vertex • Conclusions & perspectives

  27. Standalone EGNOS DGPS1 DGPS2 4. Results A. Area measurement: continuous method For continuousmethod the impact of corrections (DGPS) is visible but not very consistent EGNOS corrections does not improve the result Outliers eliminated

  28. With EGNOS, vertex (5s) = stop&go (1s) Standalone EGNOS DGPS1 DGPS2 4. Results A. Area measurement: vertex / stop&go method The vertex method is more accurate than stop&go, except when EGNOS is used

  29. Standalone EGNOS DGPS1 DGPS2 4. Results A. Area measurement: continuous versus vertex / stop&go standalone EGNOS Use vertex method Use continuous method with DGPS DGPS Use stop&go method EGNOS

  30. Continuous Stop&Go Vertex 4. Results A. Area measurement For stop&go and vertex methods, use differential correction (EGNOS and DGPS)

  31. In 2009 and 2010 tests same trend for continuously recorded data using EGNOS corrections Standalone EGNOS DGPS 4. Results A. Area measurement : multi-year results for GeoXT receivers In 2004 – no standalone data

  32. Improvement of results is visible for THALES receiver (tested in 2004) For Leica GS20 the improvement exist but it is not significant (tested in 2004) For GeoXT the impact of EGNOS corrections it is not visible (tested in 2009 and 2010) Standalone EGNOS 4. Results A. Area measurement : EGNOS impact on area measurement, continuous method, using different GNSS receivers In 2004 - no standalone data for GeoXT - tests carried out during different periods

  33. Standalone EGNOS DGPS1 DGPS2 4. Results A. Point position accuracy For stop&go and vertex method the impact of DGPS corrections on point accuracy is significant. Standalone < EGNOS < DGPS Stop&Go < Vertex Results from parcel A (8 key points, n = 12 / point)

  34. Outline • GNSS …. overview • Research objectives • Field measurements • Results for area measurement and point position accuracy • impact of corrections: EGNOS, DGPS • impact of measurement method: continuous, stop&go, vertex • Conclusions & perspectives

  35. 5. Conclusions & perspectives • A. Area measurement • using continuous method the impact of corrections (EGNOS, DGPS, etc.) is limited OK for standalone mode, different results f. of receiver and conditions • use of corrections (EGNOS, DGPS, etc.) for Stop&Go / vertex methods improves significantly the results • B. Point position accuracy • in term of absolute positioning the differentialcorrections improves significantly the results • using EGNOS corrections the results are few improved • Differential corrections improve results in term of area measurement and absolute positioning • Several base stations networks exists • We can use same receiver in : • standalone mode, continuous method for area measurement • EGNOS or DGPS mode, vertex method for point measurement EGNOS  more tests !!!!

  36. 5. Conclusions & perspectives • A. Area measurement • repeat test using other GNSS receivers (Leica, Garmin, etc.) • analyze impact of shape, mask, etc … • B. Point position accuracy • analyze the impact of point accuracy on area measurement taking into account size and shape of parcel • propose a protocol to validate GNSS devices for point position accuracy (function of measurement mode, etc …)

  37. Thank you for your attention!

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