a case study of pleiades tri-stereo imagery: nadezhda malyavina, head of racurs production...
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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, interpretability, 3D modeling potential.
Petr Titarov, Software developer, Racurs
Elena Kobzeva, Chief Engineer, Technology 2000
13th International Scientific and Technical Conference
From Imagery to Map: Digital Photogrammetric Technologies
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
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
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Pushbroom imagery orientation models
Pushbroom imagery orientation models
Rigorous Universal Replacement
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Universal pushbroom models
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Test dataset description
Pleiades Tri-Stereo Imagery
Parameters Images
Image ID DS_PHR1A_201306010719183 _ SE1_PX_E060N56_0920_01800
DS_PHR1A_201306010719416 _ SE1_PX_E060N56_0920_01876
DS_PHR1A_201306010719523 _ SE1_PX_E060N56_0920_01876
Imaging date and time 2013-06-01 07:19:53.4 2013-06-01 07:20:16.6 2013-06-01 07:20:27.4
Viewing angle along track 10.1° -2.7° -8.5°
Viewing angle across track 1.4 ° 1.9° 2.1 °
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 Pan Image, GSD 0.7 m
MS Image, GSD 2.8 m MS Image, GSD 2.8 m
Test dataset description
Ground points set
Ground coordinates accuracy: 0.2-1.0 m RMSE
Points measurements in the images accuracy: 1 pixel
Pleiades imagery orientation accuracy assessment: methodology
Scheme #
GCPsnumber
Orientation model Objective
I 0 RPC Supplied RPC accuracy assessment
II 0 RPC + shiftAssessment of accuracy achievable using supplied RPC and tie points (but no ground control)
III 1 RPC + shift Assessment of accuracy achievable with RPC and a single ground control point
IV 4 RPC + affine Assessment of accuracy achievable with RPC and the typical ground control point configuration, applying affine refinement
V 4 RPC + shift To compare the efficiency of affine and shift RPC refinements
VI 10 RPC + shiftTo find out if the accuracy improves with increasing the number of ground control points in the case of applying shift RPC refinement
VII 10 RPC + affineTo find out if the accuracy improves with increasing the number of ground control points in the case of applying affine RPC refinement
VIIIall
availableRPC + shift Assessment of the best achievable accuracy in the case of applying shift RPC refinement
IXall
availableRPC + affine Assessment of the best achievable accuracy in the case of applying affine RPC refinement
X 4 Affine 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).
XI 10 Parallel-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).
XII 10 DLT
XIII 10 Affine
Pleiades imagery orientation accuracy: single images
Image phr1a_p_201306010719533_sen_624609101-001
Scheme GCPs count Orient. model GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
I 0 RPC - - 33 3.1 4.9
III 1 RPC+shift 0.0 0.0 32 1.0 2.3
IV 4 RPC+affine 0.4 0.5 29 1.0 1.9
V 4 RPC+shift 0.6 0.8 29 1.0 2.0
VI 10 RPC+shift 0.7 1.0 23 1.1 1.9
VII 10 RPC+affine 0.7 1.0 23 1.0 1.9
VIII 33 RPC+shift 1.0 2.2 0 - -
IX 33 RPC+affine 0.9 2.3 0 - -
X 4 affine 0.0 0.0 29 2.6 4.2
XI 10 par.persp. 0.8 1.3 23 2.2 3.9
XII 10 DLT 1.2 1.7 23 1.9 3.0
XIII 10 affine 1.6 2.4 23 1.8 3.4
Pleiades imagery orientation accuracy : single images
Image phr1a_p_201306010720166_sen_624610101-001
Scheme GCPs count Orient. model GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
I 0 RPC - - 38 3.9 4.6
III 1 RPC+shift 0.0 0.0 37 0.8 1.5
IV 4 RPC+affine 0.1 0.2 34 0.7 1.7
V 4 RPC+shift 0.3 0.4 34 0.7 1.5
VI 10 RPC+shift 0.6 0.9 28 0.7 1.3
VII 10 RPC+affine 0.5 0.8 28 0.7 1.3
VIII 38 RPC+shift 0.6 1.4 0 - -
IX 38 RPC+affine 0.6 1.2 0 - -
X 4 affine 0.0 0.0 34 4.5 7.6
XI 10 par.persp. 2.0 4.1 28 2.5 4.4
XII 10 DLT 0.8 1.2 28 1.5 3.0
XIII 10 affine 2.8 4.8 28 2.8 5.7
Pleiades imagery orientation accuracy : single images
Image phr1a_p_201306010720273_sen_624611101-001
Scheme GCPs count Orient. model GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
I 0 RPC - - 38 4.2 5.4
III 1 RPC+shift 0.0 0.0 37 0.9 1.8
IV 4 RPC+affine 0.1 0.2 34 0.8 2.1
V 4 RPC+shift 0.3 0.3 34 0.8 2.1
VI 10 RPC+shift 0.5 0.9 28 0.7 1.8
VII 10 RPC+affine 0.5 0.8 28 0.7 1.9
VIII 38 RPC+shift 0.7 1.8 0 - -
IX 38 RPC+affine 0.6 1.7 0 - -
X 4 affine 0.0 0.0 34 6.6 11.3
XI 10 par.persp. 2.8 5.8 28 3.7 6.3
XII 10 DLT 1.9 2.6 28 2.3 4.7
XIII 10 affine 3.9 6.5 28 4.0 7.9
Pleiades imagery orientation accuracy: single images
Conclusions:
Planimetric accuracy of supplied RPC was RMSE 3.1-4.2 m (the specification is CE90 = 8.5 m).
The accuracy of 0.8-1.0 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 0.7-1.0 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.
Pleiades imagery orientation accuracy: the triplet
Triplet orientation without tie points
Scheme GCPs count
Orient. model GCP RMSE, m
GCP MAX, m
CPs count
CP RMSE, m
CP MAX, m
dS dZ dS dZ dS dZ dS dZ
I 0 RPC - - - - 38 3.8 2.2 4.9 4.9
III 1 RPC+shift 0.0 0.0 0.0 0.0 37 0.8 2.3 1.3 5.3
IV 4 RPC+aff. 0.1 0.1 0.1 0.1 34 0.8 2.0 2.0 4.3
V 4 RPC+shift 0.3 1.6 0.5 2.1 34 0.7 2.1 1.5 4.4
VI 10 RPC+shift 0.6 1.4 1.1 2.5 28 0.7 2.3 1.4 4.9
VII 10 RPC+affine 0.5 1.5 1.0 2.7 28 0.8 2.4 1.8 5.0
VIII 38 RPC+shift 0.7 2.2 1.4 5.9 0 - - - -
IX 38 RPC+affine 0.6 2.1 1.2 6.1 0 - - - -
X 4 affine 0.0 0.0 0.0 0.0 34 13.5 51.4 36.9 125.6
XI 10 par.persp. 2.5 11.5 5.5 23.7 28 3.4 13.7 7.3 34.3
XII 10 DLT 0.9 3.1 2.2 6.1 28 1.9 19.1 4.9 49.3
XIII 10 affine 2.4 10.3 5.1 21.4 28 3.5 12.9 7.2 30.1
Pleiades imagery orientation accuracy: the triplet
Triplet orientation with tie points
Scheme GCPs count
Orient. model
GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
dS dZ dS dZ dS dZ dS dZ
II 0 RPC+shift - - - - 38 3.6 2.2 4.5 5.7
III 1 RPC+shift 0.2 0.6 0.2 0.6 37 0.7 2.2 1.4 5.6
IV 4 RPC+affine 0.1 0.1 0.1 0.1 34 0.8 2.0 2.0 4.3
V 4 RPC+shift 0.3 1.6 0.5 2.2 34 0.7 2.1 1.5 4.7
VI 10 RPC+shift 0.6 1.4 1.1 2.4 28 0.7 2.3 1.4 5.4
VII 10 RPC+affine 0.6 1.4 1.1 2.4 28 0.7 2.3 1.4 5.2
VIII 38 RPC+shift 0.6 2.1 1.2 5.0 0 - - - -
IX 38 RPC+affine 0.6 2.0 1.1 5.0 0 - - - -
X 4 affine 0.0 0.0 0.0 0.0 34 8.0 38.0 19.3 67.8
XI 10 par.persp. 4.5 28.7 9.5 64.2 28 5.0 31.9 12.6 95.2
XII 10 DLT 3.6 30.5 7.4 67.3 28 4.5 34.6 11.1 106.2
XIII 10 affine 4.5 30.9 9.5 70.5 28 5.4 33.8 13.6 105.8
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 0.7-1.0 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 0.7-0.8 m and the vertical accuracy of 2.2-2.3 m were achieved. Increasing GCPs number to 4 allowed improving the results but not significantly, the vertical accuracy became of 2.0-2.1 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:
Pleiades imagery orientation accuracy: stereopairs vs. the triplet
Triplet orientation (maximum B:H=0.37)
Scheme GCPs count
Orient. model
GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
dS dZ dS dZ dS dZ dS dZ
I 0 RPC - - - - 25 3.6 2.0 4.5 4.9
III 1 RPC+shift 0.0 0.0 0.0 0.0 24 0.8 2.2 1.2 5.3
IV 4 RPC+affine 0.1 0.1 0.1 0.1 21 0.7 2.0 1.1 4.3
V 4 RPC+ shift 0.3 1.6 0.5 2.1 21 0.7 1.9 1.4 4.0
VI 10 RPC+ shift 0.6 1.3 1.2 2.1 15 0.6 2.2 0.9 4.3
VII 10 RPC+affine 0.5 0.6 0.8 1.2 15 0.7 2.1 1.2 4.4
Pleiades imagery orientation accuracy: stereopairs vs. the triplet
Forward + backward stereopair orientation (B:H=0.37)
Scheme GCPs count
Orient. model
GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
dS dZ dS dZ dS dZ dS dZ
I 0 RPC - - - - 25 3.5 1.9 4.5 4.3
III 1 RPC+ shift 0.0 0.0 0.0 0.0 24 0.8 2.2 1.3 4.9
IV 4 RPC+affine 0.1 0.2 0.2 0.2 21 0.7 2.0 1.1 4.7
V 4 RPC+ shift 0.3 1.7 0.6 2.0 21 0.7 1.9 1.4 3.6
VI 10 RPC+ shift 0.7 1.3 1.2 2.2 15 0.6 2.2 1.0 3.9
VII 10 RPC+affine 0.5 0.7 0.8 1.1 15 0.7 2.1 1.3 4.0
Pleiades imagery orientation accuracy: stereopairs vs. the triplet
Forward + nadir stereopair orientation (B:H=0.25)
Scheme GCPs count
Orient. model
GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
dS dZ dS dZ dS dZ dS dZ
I 0 RPC - - - - 25 3.3 2.6 4.2 7.7
III 1 RPC+shift 0.0 0.0 0.0 0.0 24 0.8 2.8 1.4 7.8
IV 4 RPC+ affine 0.0 0.6 0.0 0.8 21 0.7 2.2 1.2 6.4
V 4 RPC+shift 0.4 1.6 0.5 2.5 21 0.7 2.2 1.3 6.3
VI 10 RPC+shift 0.6 1.5 1.0 2.4 15 0.7 2.7 1.3 6.7
VII 10 RPC+ affine 0.5 1.0 0.8 1.6 15 0.7 2.5 1.4 6.5
Pleiades imagery orientation accuracy: stereopairs vs. the triplet
Nadir + backward stereopair orientation (B:H=0.11)
Scheme GCPs count
Orient. model
GCP RMSE, m GCP MAX, m CPs count CP RMSE, m CP MAX, m
dS dZ dS dZ dS dZ dS dZ
I 0 RPC - - - - 25 4.1 3.5 4.9 9.4
III 1 RPC+shift 0.0 0.0 0.0 0.0 24 1.0 3.0 1.7 8.0
IV 4 RPC+ affine 0.2 1.8 0.3 2.5 21 0.7 3.4 1.5 10.1
V 4 RPC+shift 0.4 2.7 0.6 4.0 21 0.7 3.3 1.2 8.8
VI 10 RPC+shift 0.6 2.4 1.0 4.6 15 0.7 3.3 1.4 8.0
VII 10 RPC+ affine 0.5 2.2 0.7 4.3 15 0.7 2.9 1.5 7.8
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).
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
Creating 3D models using PHOTOMOD: deriving DEM
Creating 3D models using PHOTOMOD: generating orthoimagery
Creating 3D models using PHOTOMOD: 3D vectorization
Creating 3D models using PHOTOMOD: automatic 3D modeling
PHOTOMOD. Object texturing
PHOTOMOD. Model texturing using close-range imagery
PHOTOMOD. Import of “special” objects
PHOTOMOD. Creating 3D model of the city of Yekaterinburg
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
Interpretation results
Imagery Number of recognized objects
Images only
Add. Info
Field ve-rification
Not re-cognized
Pleiades 103 92 21 20
WV 2 106 90 19 19
A3 126 78 15 14
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
PHOTOMOD. Comparing different types of objects
Single-storey private houses Multistory city buildings
Pleiades A3 Pleiades A3
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)
Assessment of objects positioning accuracy
Parameter WV2 ortho Pleiades ortho Pleiades stereo
Number of measurements 371 366 371
Mean error, m 1.3 1.5 0.9
Maximum error, m 4.0 5.4 3.5
Error distribution – vector map of scale 1: 2 000
Error distribution – vector map of scale 1 : 5 000
35%
40%
25% 35%
40%
25%
58%33%
9%
85%
15%
1%
81%
17%
2%
97%
3%
0-0,4 mm
0.4-08 mm
larger than 0.8 mm
0-0,4 mm
0.4-08 mm
larger than 0.8 mm
PHOTOMOD. Drawing contour lines
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
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: 10000. If additional sources of data are available and field verification is possible, it is possible to create and update 1 : 5 000 scale maps of moderate-sized inter-settlement areas.
Accuracy and interpretability of Pleiades imagery are comparable to ones of WordView-2.
Conclusions:
Acknowledgement
RACURS and TECHNOLOGY 2000
express their gratitude to
ASTRIUM GeoInformation Services
for the Pleiades Tri-Stereo Imagery Product over the city of Yekaterinburg
A Case Study of Pleiades Tri-Stereo Imagery
Thank you for attention !
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