HANDLING OF HIGH RESOLUTION SPACE IMAGES IN Z/I IMAGESTATION
J. Biard , M. Madani*, K. Jacobsen**
Z/l Imaging Corporation, Alabama, USA
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University Hanover, Germany
E-mail: jbiard(@àziimaging.com, msmadani@ziimaging.com, jacobsen@ipi.uni-hannover.de
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Commission I, Working Group 1/5
KEY WORDS: High resolution, Satellite, Orientation, Matching, Analysis
ABSTRACT:
High resolution space images are becoming more and more important as their resolution and availability improve. Images having a
ground pixel size of 0.6 m or 1.0 m are competing with classical aerial photos. The space images cover large areas, reducing the
number of control points needed. If rational polynomial coefficients (RPC) are available, the number of control points can be
reduced even further. Using RPCs, mapping is also possible without control points if only relative accuracy is required, and if an
absolute accuracy in the range of a standard deviation of £12 m is acceptable.
Stereo models and individual images taken by IKONOS, QuickBird and SPOT 5 have been analyzed, as well as IRS-1C level 1B
and Landsat images. The achieved accuracy is sufficient for mapping and orthoimage generation. Digital surface models (DSM) are
generated by image matching, showing the height of the visible surface. DSMs can be reduced to digital elevation models (DEM ),
which can be used for producing orthoimages. It is not necessary to use the same sensor for achieving the DEM, so it is possible to
compute an IKONOS orthoimage based on a SPOT 5 DEM.
1. INTRODUCTION
With a ground pixel size of 0.6m for QuickBird and 1m for
IKONOS images, there is now direct competition between high
resolution space images and aerial photos with a scale of
1:50,000 to 1:80,000. QuickBird images have a swath width of
16.5 km. This can only be achieved with aerial images at a
scale of 1:80,000 from a flying height of 12.2 km, with view
directions that are not optimal for the generation of
orthoimages. In addition, digital images are not influenced by
film grain, resulting in better radiometric quality. In the near
future, several high resolution optical space systems will be put
in operation, resulting in improvements in the resolution,
availability, variety, and cost of space images. This will cause
a permanent growth in the use of space images for mapping.
2. IMAGESTATION DIGITAL MENSURATION
(ISDM) SATELLITE TRIANGULATION
ISDM Satellite Triangulation is a flexible, modular extension to
the Z/I Imaging ISDM product. It performs analytical block
adjustment of satellite images using fundamental, well-
established photogrammetric techniques. At the core is a block
adjustment engine that performs a unified, weighted,
simultaneous least squares adjustment of ground point
coordinates and image parameters. This core is coupled with
modules that implement mathematical models for various
remote sensors. This allows support for new satellite remote
sensor types to be developed and added with relative ease.
The block adjustment engine is flexible. It accommodates
variations in the number and scope of adjustable parameters
associated with satellite images. These parameters can be the
12 well-known exterior orientation parameters (satellite
position, satellite velocity, satellite attitude bias, and satellite
attitude bias rate), or some other number, depending on what is
needed to support the particular remote sensor type. Parameters
can be associated with all images for a particular remote sensor,
with all images in a single data acquisition scene, or with
individual images. Table 1 lists the number and scope of
parameters for the currently implemented satellite remote
sensor types.
The mathematical model used for a particular satellite remote
sensor is implemented in a Microsoft Common Object Model
(COM)-based code module. A remote sensor module
calculates — image-to-ground projections, | ground-to-image
Remote Sensor Type
Parameters
Scope of orientation parameters
SPOT 1-5 Level 1A
Multispectral (ms),
Panchromatic (pan),
& Supermode pan
12 Satellite EO Parameters:
Position X, Y, Z
Velocity Vx, Vy, Vz
Attitude Bias ©, D, K
Attitude Bias Rate Vo, Vo, Vk
Scene composed of all images from a
single orbit pass
QuickBird Basic Imagery, pan & ms 12 Satellite EO Parameters Scene
IRS-1C & 1D Level 1A pan 12 Satellite EO Parameters Scene
Landsat TM ms 12 Satellite EO Parameters Image
Landsat7 ETM+ ms & pan
IKONOS (CARTERRA Geo) pan & 6 Affine Parameters: [Image
ms Line bias, drift, scale
Sample bias, drift, scale
Table 1: Parameters for ISDM Satellite Triangulation Sensor Types
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