BUILDING A CONSISTENT GEOMETRIC FRAME OVER SPARSE ISLANDS 
USING SPOT 5 DATA 
T. Yoshino 3 , H. Muraki 3 , Y. Yin 3 , M. Bemard b 
3 ImageONE Co., Ltd., Shinjuku Daiichiseimei Bldg. 12F, 2-7-1 Nishi Shinjuku Shinjuku-ku, Tokyo 163-0712 Japan 
yoshino@imageone.co.jp, muraki@imageone.co.jp, yy@imageone.co.jp 
Spot Image, 5 rue des Satellites, BP14359, 31030 Toulouse, France - marc.bemard@spotimage.fr 
KEY WORDS: Mapping, DEM, orthoimage, Reference3D, SPOT, geometric, accuracy 
ABSTRACT: 
Operating in panchromatic mode onboard SPOT 5, the HRS instrument has two telescopes, one pointing forward and one aft of the 
satellite. HRS is thus able to cover an area of 600 km x 120 km in a single pass (i.e. 72 000 km 2 stereoscopic strips). Moreover, the 
extremely precise ancillary metadata of SPOT 5 allows accurate geometric processing with no ground control points. Thus SPOT 5 
stereoscopic imagery becomes one of main satellite data sources for accurate DEM extraction as well as for building a common 
geometric frame over large areas. Spot Image and French National Cartographic Institute (IGN) decided in 2002 to design and build 
a worldwide accurate database called Reference3D™ using HRS data. This database consists of three information layers: Digital 
Elevation Model at 1-arc-second resolution (DTED level 2), Orthoimage at 5m resolution and Quality Masks. The production 
process aiming at drastic accuracy requirements (circular horizontal accuracy better than 16m and elevation accuracy better than 
10m for 90% of the points), is therefore rather complex. Huge efforts have been made to standardize the production process in order 
to offer attractive delivery times and affordable prices. As of June 30th 2008, the Reference3D database will cover more than 30 
million km 2 .Technically speaking, the above-mentioned accuracy requirements, achieved without any control points nor map 
support, would have been regarded as a totally utopian goal by the whole mapping community even one decade ago. However, the 
dramatic progression of space-photogrammetry techniques in the recent years really allows the challenge to be overcome, as shown 
by scientific assessments of the Reference3D products performed by independent users. The 1 st part of the paper will summarize the 
most significant assessments performed by major players within the geospatial community.The large 120km swath of HRS is 
particularly helpful over maritime areas populated by sparse islands, where achieving a global consistent frame is really challenging. 
To confirm this ability, ImageONE Co., Ltd. performed accuracy assessment on two Reference3D geocells over sparse islands 
located off-shore the Northern coast of Japan. The production area also includes a portion of Hokkaido province. 
The paper will then focus on the assessment performed by ImageONE Co., Ltd. comparing Reference3D against digital map and 
National DEM from the Geographical Survey Institute (GSI), government of Japan.In conclusion, the assessments show that the 
120km swath of HRS is a very powerful tool to build highly consistent frame over areas that were once very difficult to map with a 
good relative accuracy. 
Commission VII, WG VII/7 
1. INTRODUCTION 
Digital Elevation Model of 1-arc-sencond resolution (DTED 
level 2), orthoimage of 5m resolution and Quality Masks. 
The Reference3D is a world wide accurate DEM data base 
generated from HRS sensor on board SPOT 5 without any 
ground control points. Some assessments performed world wide 
showed that the Reference3D met its standard specifications. 
Two most significant assessments are presented in this paper, 
one comparing against STRM DEM, another comparing against 
geodetic points of network and nation-wide DTM. In last year, 
twelve Reference3D tiles over Japan became available. This 
paper will focus on the assessment of DEM of two Reference3D 
tiles performed by ImageONE Co., Ltd. comparing against a set 
of points of Japan Triangulation Network and National DEM of 
GSI. The horizontal accuracy assessment of the orthoimage 
from the same Reference3D tiles will also be presented in this 
paper. 
The orthoimage layer absolute horizontal accuracy is 16m 
(circular error for 90% of the points). The Reference3D product 
is delivered as a geographic tile of 1 degree by 1 degree with a 
raster DEM data set of 3601 x 3601 cells. 
The DEM layer absolute requirements are: 
horizontal circular absolute accuracy of 15m at 90% 
vertical absolute accuracy depending on the slope: 
• 1 Om at 90% for slopes lower than 20 degrees 
• 18m at 90% for slopes between 20 degrees and 40 
degrees 
• 30m at 90% for slopes greater than 40 degrees 
2. THE REFERENCE3D 
3. MAJOR ASSESSMENT OF THE REFERENCE3D 
The Reference3D is designed and built by Spot Image and 
French National Cartographic Institute (IGN) using HRS data. 
This world wide data base consists of three information layers: 
Several accuracy assessments of the Reference3D products 
have been performed at international level by independent users. 
The results showed that the Reference3D product met all its 
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