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A Case Study of Pleiades Tri-Stereo Imagery: Nadezhda Malyavina, Head of Racurs Production department September 2013, Fontainebleau, France accuracy assessment,

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Presentation on theme: "A Case Study of Pleiades Tri-Stereo Imagery: Nadezhda Malyavina, Head of Racurs Production department September 2013, Fontainebleau, France accuracy assessment,"— Presentation transcript:

1 A Case Study of Pleiades Tri-Stereo Imagery: Nadezhda Malyavina, Head of Racurs Production department September 2013, Fontainebleau, France accuracy assessment, interpretability, 3D modeling potential. Petr Titarov, Software developer, Racurs Elena Kobzeva, Chief Engineer, Technology 2000 From Imagery to Map: Digital Photogrammetric Technologies 13 th International Scientific and Technical Conference From Imagery to Map: Digital Photogrammetric Technologies

2 A Case Study of Pleiades Tri-Stereo Imagery Pleiades imagery orientation accuracy assessment 3D modeling of urban area (the city of Yekaterinburg) Creating and updating topographic maps using Pleiades imagery Contents

3 Pleiades imagery orientation accuracy assessment Pushbroom imagery orientation models Test dataset description Pleiades imagery orientation accuracy Rigorous, rational polynomial (RPC) and universal pushbroom models Pleiades Tri-Stereo product and ground points set Orientation accuracy of single Pleiades images, stereopairs and the triplet

4 Pushbroom imagery orientation models Pushbroom imagery orientation models RigorousUniversalReplacement

5 Rigorous orientation model Ray reconstruction: Ray vertex (sensor position): Viewing direction:

6 Rational polynomial model (RPC) are polynomials: where The coordinates in the RPC formulae are normalized to fall into the range of [-1;1].

7 Rational polynomial model (RPC) refinements RPC adjustment: bias removal RPC adjustment: affine refinement

8 Universal pushbroom models Parallel-perspective model Direct Linear Transformation (DLT) Affine model

9 Test dataset description Pleiades Tri-Stereo Imagery ParametersImages Image ID DS_PHR1A_ _ SE1_PX_E060N56_0920_01800 DS_PHR1A_ _ SE1_PX_E060N56_0920_01876 DS_PHR1A_ _ SE1_PX_E060N56_0920_01876 Imaging date and time :19: :20: :20:27.4 Viewing angle along track10.1°-2.7°-8.5° Viewing angle across track1.4 °1.9°2.1 °

10 Test dataset description Pleiades Tri-Stereo Imagery – Bundle Product Pan Image, GSD 0.7 m MS Image, GSD 2.8 m The images were pan-sharpened using PHOTOMOD Pan Image, GSD 0.7 m MS Image, GSD 2.8 m

11 Test dataset description Ground points set Ground coordinates accuracy: m RMSE Points measurements in the images accuracy: 1 pixel

12 Pleiades imagery orientation accuracy assessment: methodology Scheme # GCPs number Orientation modelObjective I0RPCSupplied RPC accuracy assessment II0RPC + shift Assessment of accuracy achievable using supplied RPC and tie points (but no ground control) III1RPC + shiftAssessment of accuracy achievable with RPC and a single ground control point IV4RPC + affine Assessment of accuracy achievable with RPC and the typical ground control point configuration, applying affine refinement V4RPC + shiftTo compare the efficiency of affine and shift RPC refinements VI10RPC + shift To find out if the accuracy improves with increasing the number of ground control points in the case of applying shift RPC refinement VII10RPC + affine To find out if the accuracy improves with increasing the number of ground control points in the case of applying affine RPC refinement VIII all available RPC + shiftAssessment of the best achievable accuracy in the case of applying shift RPC refinement IX all available RPC + affineAssessment of the best achievable accuracy in the case of applying affine RPC refinement X4Affine Assessment of accuracy achievable with the affine universal model and a minimal set of ground control points, and comparison with orientation with RPC (the ground control points set was the same as in Schemes III and IV). XI10Parallel-perspective Assessment of accuracy achievable with the various universal models and comparison with orientation with RPC (the ground control points set was the same as in Schemes V and VI). XII10DLT XIII10Affine

13 Pleiades imagery orientation accuracy: single images Image phr1a_p_ _sen_ SchemeGCPs countOrient. modelGCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m I0 RPC III1 RPC+shift IV4 RPC+affine V4 RPC+shift VI10 RPC+shift VII10 RPC+affine VIII33 RPC+shift IX33 RPC+affine X4 affine XI10 par.persp XII10 DLT XIII10 affine

14 Pleiades imagery orientation accuracy : single images Image phr1a_p_ _sen_ SchemeGCPs countOrient. modelGCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m I0 RPC III1 RPC+shift IV4 RPC+affine V4 RPC+shift VI10 RPC+shift VII10 RPC+affine VIII38 RPC+shift IX38 RPC+affine X4 affine XI10 par.persp XII10 DLT XIII10 affine

15 Pleiades imagery orientation accuracy : single images Image phr1a_p_ _sen_ SchemeGCPs countOrient. modelGCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m I0 RPC III1 RPC+shift IV4 RPC+affine V4 RPC+shift VI10 RPC+shift VII10 RPC+affine VIII38 RPC+shift IX38 RPC+affine X4 affine XI10 par.persp XII10 DLT XIII10 affine

16 Pleiades imagery orientation accuracy: single images Conclusions: Planimetric accuracy of supplied RPC was RMSE m (the specification is CE90 = 8.5 m). The accuracy of m RMSE (i.e. rather close to the limit set by the measurements accuracy) was achieved with a single GCP, applying shift refinement to the supplied RPC model. The accuracy of m RMSE was achieved with 4 GCPs, applying either shift of affine RPC refinement. Further increasing the number of GCPs did not improve the accuracy. The orientation accuracy achieved with universal methods varied over a wide range and was significantly worse than one achieved with RPC and bias removal.

17 Pleiades imagery orientation accuracy: the triplet Triplet orientation without tie points SchemeGCPs count Orient. modelGCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m dSdZdSdZdSdZdSdZ I0 RPC III1 RPC+shift IV4 RPC+aff V4 RPC+shift VI10 RPC+shift VII10 RPC+affine VIII38 RPC+shift IX38 RPC+affine X4 affine XI10 par.persp XII10 DLT XIII10 affine

18 Pleiades imagery orientation accuracy: the triplet Triplet orientation with tie points SchemeGCPs count Orient. model GCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m dSdZdSdZdSdZdSdZ I0 RPC+shift III1 RPC+shift IV4 RPC+affine V4 RPC+shift VI10 RPC+shift VII10 RPC+affine VIII38 RPC+shift IX38 RPC+affine X4 affine XI10 par.persp XII10 DLT XIII10 affine

19 Pleiades imagery orientation accuracy: the triplet Using supplied RPC and no GCPs, the achieved planimetric accuracy was 3.6 m RMSE in the case of involving tie points and 3.8 m without them; the vertical accuracy was 2.2 m in both cases. So involving tie points in the adjustment procedure did not significantly improve the accuracy; Involving GCPs made the difference between adjustment with and without tie points insignificant. The accuracy of m RMSE was achieved with 4 GCPs, applying either shift of affine RPC refinement. Using a single GCP and applying shift RPC refinement, the planimetric accuracy of m and the vertical accuracy of m were achieved. Increasing GCPs number to 4 allowed improving the results but not significantly, the vertical accuracy became of m. Further increasing the number of GCPs did not improve the accuracy. The universal methods are not suitable for stereoscopic (three dimensional) processing of Pleiades imagery. Conclusions:

20 Pleiades imagery orientation accuracy: stereopairs vs. the triplet Triplet orientation (maximum B:H=0.37) SchemeGCPs count Orient. model GCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m dSdZdSdZdSdZdSdZ I0 RPC III1 RPC+shift IV4 RPC+affine V4 RPC+ shift VI10 RPC+ shift VII10 RPC+affine

21 Pleiades imagery orientation accuracy: stereopairs vs. the triplet Forward + backward stereopair orientation (B:H=0.37) SchemeGCPs count Orient. model GCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m dSdZdSdZdSdZdSdZ I0 RPC III1 RPC+ shift IV4 RPC+affine V4 RPC+ shift VI10 RPC+ shift VII10 RPC+affine

22 Pleiades imagery orientation accuracy: stereopairs vs. the triplet Forward + nadir stereopair orientation (B:H=0.25) SchemeGCPs count Orient. model GCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m dSdZdSdZdSdZdSdZ I0 RPC III1 RPC+shift IV4 RPC+ affine V4 RPC+shift VI10 RPC+shift VII10 RPC+ affine

23 Pleiades imagery orientation accuracy: stereopairs vs. the triplet Nadir + backward stereopair orientation (B:H=0.11) SchemeGCPs count Orient. model GCP RMSE, mGCP MAX, mCPs countCP RMSE, mCP MAX, m dSdZdSdZdSdZdSdZ I0 RPC III1 RPC+shift IV4 RPC+ affine V4 RPC+shift VI10 RPC+shift VII10 RPC+ affine

24 Pleiades imagery orientation accuracy: stereopairs vs. the triplet Conclusions: The accuracy of orientation of the triplet and of the forward+backward stereopair (i.e. the stereopair with the largest base-to-height ratio) was approximately the same. The accuracy of triplet orientation was slightly better than one of the stereopairs which included the nadir image (so the stereopairs had lower base-to-height ratio).

25 Mapping and 3D modeling of urban areas Creating 3D models Deriving DEM Generating orthoimagery 3D modeling of urban area Assessment of suitability for topographic maps creating and updating Interpretability assessment Assessment of objects positioning accuracy Drawing contour lines

26 Creating 3D models using PHOTOMOD: deriving DEM

27 Creating 3D models using PHOTOMOD: generating orthoimagery

28 Creating 3D models using PHOTOMOD: 3D vectorization

29 Creating 3D models using PHOTOMOD: automatic 3D modeling

30 PHOTOMOD. Object texturing

31 PHOTOMOD. Model texturing using close-range imagery

32 PHOTOMOD. Import of “special” objects

33 PHOTOMOD. Creating 3D model of the city of Yekaterinburg

34 Interpretability assessment Source dataset: Pleiades orthoimagery, 0.5m, RGB Worldview-2 orthoimagery, 0.5m, RGB A3 orthoimagery, 0.1m, RGB Topographic interpretation samples set WV-2, GE-1 and Ikonos Scanned topographic plans of scale 1:500, contour interval 0,5 m; Vector topographic maps of scale 1:10 000, contour interval 2 m

35 Interpretation results ImageryNumber of recognized objects Images only Add. Info Field ve- rification Not re- cognized Pleiades WV A

36 Assessment of objects positioning accuracy Source dataset: Pleiades stereopair (9º and -11º), 0,5 m, PAN Pleiades orthoimagery 0.5m, RGB WV2 orthoimagery, 0.5m, RGB A3 orthoimagery 0.1m, RGB as reference data

37 PHOTOMOD. Comparing different types of objects Single-storey private housesMultistory city buildings Pleiades A3

38 Interpretability analysis 1.5 m - wide ledges are indiscernible Shape and size of multistory buildings are reconstructed correctly It is impossible to tell residential buildings from nonresidential ones Some architectural forms may be missing (the ledges are shown on one side of the building and missing on the other)

39 Assessment of objects positioning accuracy ParameterWV2 orthoPleiades orthoPleiades stereo Number of measurements Mean error, m Maximum error, m Error distribution – vector map of scale 1: Error distribution – vector map of scale 1 : ,4 mm mm larger than 0.8 mm 0-0,4 mm mm larger than 0.8 mm

40 PHOTOMOD. Drawing contour lines

41 Contour lines verification using reference data Vector topographic maps of scale 1:10 000, contour interval 2 m Contour lines derived from the Pleiades stereopair

42 Topographic mapping and 3D modeling of urban areas The 3D model created is geometrically accurate and discrete, so it is possible to access separate objects, to set attribute values for them and to perform 3D measurements - in other words, to produce geospatial databases. The model can be used for visualization and for 3D city planning. Stereoscopic measurements ensure better accuracy and interpretability than ones performed in single images, while using tri-stereo imagery reduces “blind zones”. Pleiades images are suitable for creating and updating topographic maps of scale up to 1: If additional sources of data are available and field verification is possible, it is possible to create and update 1 : scale maps of moderate-sized inter-settlement areas. Accuracy and interpretability of Pleiades imagery are comparable to ones of WordView-2. Conclusions:

43 Acknowledgement RACURS and TECHNOLOGY 2000 express their gratitude to ASTRIUM GeoInformation Services for the Pleiades Tri-Stereo Imagery Product over the city of Yekaterinburg

44 A Case Study of Pleiades Tri-Stereo Imagery Thank you for attention !


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