ul 2004 
  
  
ACCURACY OF DTM AND ORTHO GENERATED 
FROM IKONOS STERO IMAGES 
Kaczynski R.", Majde A. , Ewiak I. ? 
Institute of Geodesy and Cartography 
ul. Modzelewskiego 27, 02 - 679 Warszawa, Poland 
d 2 Eu 
rom@igik.edu.pl, ^ rene@igik.edu.pl 
Commission IV WG TV/6 
KEY WORDS: Photogrammetry, DTM, IKONOS, Orientation, Rectification 
ABSTRACT: 
DTM and orthophoto have been generated in IGiK using IKONOS along-track stereo images CARTERRA GEO Pan with B/H ratio 
1:1.8 and the accuracy analysis has been performed. Orientation of stereo images has been performed with ImageStation Multi 
Sensor Triangulation — IKONOS. 10 GCP’s have been used together with orbital orientation parameters data for the orientation of 
stereo images. The accuracy achieved on GCP's is as follows: RMSEx = 0.7 m; RMSEy = 0.6 m; RMSEz = 0.7 m and on the 23 
independent check points: RMSEx = 0.7 m; RMSEy = 0.7 m; RMSEz = 0.9 m. MATCH-T Inpho software has been used for 
generating DEM with grid 25 x 25 m using both aerial photographs in the scale 1:26 000 (as reference data) and IKONOS stereo 
images. MGE Terrain Analyst of INTERGRAPH has been used to compare both DTM's. The analysis was performed on 1820 points 
representing three terrain categories (town, grassland, hilly region). After elimination of systematic errors the following results have 
been achieved for Ikonos data: RMSEz for towns 0.7 m; for grassland 0.5 m and for hilly regions 0.7 m. Ortho has been generated 
with pixel 1 x 1 m; the achieved accuracy RMSx,y from 1 to 2 m is acceptable for mapping not only in the scale 1: 10 000 but also in 
the scale 1:5 000. 
1. DATA USED 3. ACCURACY OF DTM GENERATED FROM STEREO 
IKONOS DATA 
IKONOS along-track stereo images CARTERRA GEO Pan 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
have been collected by Spacelmaging on 4 May 2002 with Sun DTM from IKONOS stereo data has been generated using 
elevation 55? and collection elevation 78.5 and 60.7 degree. MATCH-T Inpho software and checked against the DTM 
Base ratio B/H= 1:1.8. The data has been delivered (after generated form aerial photographs. The results for three 
almost one year from the date the order has been placed !!!) as different terrain types are shown in table 1. 
16-bit in GeoTiff format with ASCII meta data file. 
The test region is located in South East Poland, it covers an area No of RMSz SD Max 
of 80 sq. km representing three different types of terrain: hills, points [m] [m] error 
agricultural land and small towns. [m] 
DTM with grid 25 x 25m and RMSz=0.8m has been generated Town 645 0.7 0.7 2.3 
with MATCH-T Inpho from 24 aerial photographs taken in Grassland 633 1.3 0.9 3.3 
scale 1:26 000 in 1988. This DTM also contains break lines Hilly 542 2.0 14 12 
and obscure areas. "Raw" DTM has been filtered. Final DTM region 
has been used as reference data. 
Orthophoto images have also been elaborated from aerial Table 1. Accuracy of "raw" DTM 
photographs with pixel size 1 x 1m and were used as reference 
data for ortho generated from IKONOS images. Topographic The results after elimination of systematic errors are shown in 
maps in scale 1:10 000 have been used as additional reference table 2. 
information. 
Thirty three natural GCP's have been identified and measured RMSz SD Mean Max 
in field by GPS technique with accuracy of RMSx,y<0.3m and [m] [m] [m] error 
RMSz<0.4m and used for orientation of IKONOS Stereo and [m] 
checking the results. Town 0.7 0.7 0.5 2.8 
Grassland 0.5 0.5 0.4 23 
Hilly 0.7 0.7 0.5 4.0 
2. ORIENTATION OF STEREO IKONOS DATA region 
  
  
  
  
4 
Orientation of stereo IKONOS data has been done on 10 GCP's 
with accuracy RMSx=0.7m RMSy=0.6m and RMSz=0.8m. 
Accuracy of orientation has been checked on 23 independent 
checkpoints. The results: RMSx,y=0.7m, RMSz=0.9m. 
Table 2. Accuracy of DTM after elimination of systematic 
errors 
463