Institute of Photogrammetry and GeoInformation
Filtering of matching data • Filtering process is performed by using variance and Foerstner roundness criteria in the matching kernel windows
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Filtering of matching data • Filtering process is performed by using variance and Foerstner roundness criteria in the matching kernel windows
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Comparison: Laser DEM and HRS DEM Test area Gars (5 x 5 km): part of Bavarian test site
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Absolute differences and standard deviations Comparison of the regularized SPOT-DEM and the reference DEM for selected areas and two surface types (SPOT DEM – Reference DEM) Reference area
Z-bias [m] non-forest / STDV
Z-bias [m] forest / STDV
Height-difference forest/non-forest
DEM-02
7.8 / 5.6
17.8 / 9.7
11.9
DEM-02 matching filter
8.5 / 4.8
15.0 / 8.0
7.5
DEM-02 median filter (DEM)
8.0 / 3.9
17.2 / 8.2
9.2
DEM-06
6.5 / 6.5
19.0 / 9.0
12.5
DEM-06 median filtering
6.2 / 4.2
16.9 / 6.8
10.7
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Comparison: Laser DEM and HRS DEM Laser
HRS-DEM of Gars Area
HRS
Area: 5 km x 5 km, height levels: 406 to 598 meters ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Difference between Laser DEM and HRS DEM
Mean height difference: 6.3 meter (not adjusted orientation), forest: 12 meter, open areas 4.1 meter sigma: 4.8 meter (max. deviation 30 meter) Area: 5 km x 5 km, height levels: 406 to 598 meters ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
DEM and orthoimage of Catalonia
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Barcelona Test Site (DEM accuracy without GCP) Reference area
Size of Area
Mean Height Difference [m]
STDV [m]
Min / Max
SPOT-HRS-DEM Barcelona City
71 km²
11.2
4.4
-47 / +37
Rural Area
161 km²
10.4
5.3
-59 / +53
Moderate Mountain
105 km²
11.1
6.5
-62 / +63
Montserrat (steep mountains)
84 km²
9.8
13.5
-158 / +191
Whole area
1882 km²
10.0
6.3
-158 / +191
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Comparison of SPOT and SRTM DEM Reference area
Size of Area
bias [m]
STDV [m]
Min / Max
SPOT-HRS-DEM Barcelona City
71 km²
11.2
4.4
-47 / +37
Rural Area
161 km²
10.4
5.3
-59 / +53
Moderate Mountain
105 km²
11.1
6.5
-62 / +63
Montserrat
84 km²
9.8
13.5
-158 / +191
Whole area
1882 km²
10.0
6.3
-158 / +191
Catalonia Area
SRTM-DEM Barcelona City
71 km²
1.0
4.7
-22 / +25
Rural Area
161 km²
-1.5
7.2
-98 / +62
Moderate Mountain
105 km²
-1.4
8.7
-218 / +135
Montserrat
84 km²
-1.8
25.2
-484 / +394
Whole area
623 km²
-1.2
8.5
-484 / +394
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Fusion of SPOT and SRTM DEM Catalonia Area SRTM DEM as reference for mean height Reference area
Size of Area
bias [m]
STDV [m]
Min / Max
Barcelona City
71 km²
0.9
3.7
-23 / +28
Rural Area
161 km²
-1.3
4.9
-62 / +48
Moderate Mountain
105 km²
-1.0
5.6
-70 / +78
Montserrat
84 km²
-1.5
11.1
-183 / +201
Whole area
623 km²
-1.0
5.7
-183 / +201
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Improvement of DEM (SPOT + SRTM) with fusion
forest open area build up
forest open area build up ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Fusion of SPOT and SRTM DEM
forest open area build up
forest open area build up ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Improvement of exterior orientation Pitch angle and stereo angle corrections estimated from 6 GCP (pitch angle: HRS1: 0.00007º, stereo angle: HRS2: 0.0004º) Reference area
Size and Accuracy of Ref-DEM
Mean Height Difference [m]
Std. Dev. [m] (DEM points)
DEM-01, Prien
5 x 5 km, 0.5 m
1.2
5.1
DEM-02, Gars
5 x 5 km, 0.5 m
1.1
6.3
DEM-03, Peterskirchen
5 x 5 km, 0.5 m
-0.7
5.5
DEM-04, Taching
5 x 5 km, 0.5 m
-0.7
5.4
DEM-05, Inzell
10 x 10 km, 5 m
0.1
7.5
50 x 30 km, 2-3 m
0.4
4.9
DEM-06, Vilsbiburg
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Test area Gars (rolling area) (results IPI Hannover) RMSE [m]
bias [m]
RMSE bias
RMSE as Function of terrain inclination
DSM: all points
10.2
-5.5
8.5
8.7 + 10.6 ∗ tan α
DSM: open areas
6.7
-3.0
5.9
6.4 + 4.9 ∗ tan α
DSM: forest
17.0
-14.3
9.2
16.4 + 3.4 ∗ tan α
DEM: all points
5.7
-2.0
5.1
5.0 + 5.4 ∗ tan α
DEM: open areas
4.4
-1.3
4.1
4.2 + 1.6 ∗ tan α
DEM: forest
12.3
-8.5
8.6
10.0 + 6.9 ∗ tan α
DEM = DSM filtered with Hannover program RASCOR ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Test area Inzell (mountainous) (results IPI Hannover) 68% forest, DEM only partly by laser scanning, mainly from map with SZ=+/-5m RMS [m]
bias [m]
RMS bias
RMS as function of terrain inclination
DSM: all points
17.2
-10.3
13.8
10.7 +36.1 ∗ tan α
DSM: open area
9.8
-4.7
8.7
6.1 + 39.6 ∗ tan α
DSM: forest
19.9
-13.0
15.0
17.9 + 8.5 ∗ tan α
DEM: all points
13.7
-7.1
11.7
7.9 + 45.7 ∗ tan α
DEM: open area
6.7
-2.5
6.2
4.8 + 26.1 ∗ tan α
DEM: forest
17.4
-10.8
13.7
16.2 + 7.4 ∗ tan α
DEM = DSM filtered with Hannover program RASCOR white = open area black = forest ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Conclusion of DEM generation with SPOT 5 HRS Results HRS-Data of very good quality (image and ancillary data) - two orthoimages match with pixel accuracy, applying a small shift value! Comparison to reference DEM show low standard deviations for single points but still some blunders and artifacts in regularized DEM Absolute accuracy of DEM without GCP is in the order of 10 meter, with few GCP just one/two parameters of exterior orientation can be estimated for absolute height accuracy of 1-2 meter for the DEM Further work Improvement of dense matching (region growing) algorithm by introducing more constraints and object information Improvement of exterior orientation with few ground control points in more cases (which parameters can be / have to be improved?) DEM fusion with SRTM DEMs and other sources ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
OrbView-3 stereo model in city area, same orbit, h/b = 1.4 quality image of matching OrbView-3 stereo model grey value 255 = correlation coefficient = 1.0 grey value 127 = correlation coefficient = 0.5 grey value 0 = correlation coefficient = < 0.5
problems in city with narrow streets and steep areas, high correlation values in open areas
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
IKONOS stereo model, same orbit, h/b = 7.5
Optimal conditions for automatic image matching Nearly all points matched Accuracy of building heights = 1.7m not accepted frequency distribution correlation coefficient
Corresponding to Spx = 0.22 GSD Confirmed by ray intersection Spy = 0.25 GSD
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006
Institute of Photogrammetry and GeoInformation
Conclusion Automatic image matching of very high resolution space images in city areas more difficult like for lower resolution – more strong influence of vertical or inclined objects Images of stereo scene from same day optimal, but 10 days difference in time usually not a problem Vertical accuracy not linear depending upon height to base relation because matching not so accurate for large convergence angle (large base) Optimal height to base relation ~ 3.0, but depending upon object and area Different matching results not caused by different sensors, only caused by different geometric and imaging conditions Only smaller GSD of QuickBird leads to more detailed and more accurate result
ISPRS Technical Commission I Symposium “From Sensors To Imagery”, Paris – Marne la Vallée, France, 3-6 July 2006