-B3, 2012 
  
  
D 70 80 90 10 
imma 
ink transform. 
  
) Gamma 
  
»1, Gamma 
  
5i, Gamma 
row three) using 
miglobal Match- 
rn Analysis and 
Evaluation of 
tric differences. 
elligence 31(9), 
omy and evalua- 
algorithms. Intl. 
ddlebury Stereo 
tric local trans- 
European Con- 
PHOTOGRAMMETRIC MODEL BASED METHOD OF AUTOMATIC ORIENTATION 
OF SPACE CARGO SHIP RELATIVE TO THE INTERNATIONAL SPACE STATION 
Yuri B. Blokhinov *, Alexey S. Chernyavskiy, Sergei Y. Zheltov 
State Research Institute of Aviation Systems (FGUP GosNIIAS), Moscow, Russia 
(yury.blokhinov, achern, zhl)@gosniias.ru 
Commission III, WG III/1 
KEY WORDS: Digital, Photogrammetry, Modelling, Orientation, Automation, International, Space, Real-time 
ABSTRACT: 
The technical problem of creating the new Russian version of an automatic Space Cargo Ship (SCS) for the International Space 
Station (ISS) is inseparably connected to the development of a digital video system for automatically measuring the SCS position 
relative to ISS in the process of spacecraft docking. This paper presents a method for estimating the orientation elements based on 
the use of a highly detailed digital model of the ISS. The input data are digital frames from a calibrated video system and the initial 
values of orientation elements, these can be estimated from navigation devices or by fast-and-rough viewpoint-dependent algorithm. 
Then orientation elements should be defined precisely by means of algorithmic processing. The main idea is to solve the exterior 
orientation problem mainly on the basis of contour information of the frame image of ISS instead of ground control points. A 
detailed digital model is used for generating raster templates of ISS nodes; the templates are used to detect and locate the nodes on 
the target image with the required accuracy. The process is performed for every frame, the resulting parameters are considered to be 
the orientation elements. The Kalman filter is used for statistical support of the estimation process and real time pose tracking. 
Finally, the modeling results presented show that the proposed method can be regarded as one means to ensure the algorithmic 
support of automatic space ships docking. 
1. INTRODUCTION 
The primary goal of the projected television measuring system 
of the planned Space Cargo Ship (SCS) for the International 
Space Station (ISS) is to carry out the monitoring of mutual 
position of SCS and ISS in the process of spacecraft docking 
approach. Continuous video tracking should be done in 
automatic mode and should perform the following 
measurements: angles of deviation SCS from the line of sight, 
distance and radial speed of SCS, and angles of rotation 
between the active and passive ships. 
In order to perform these calculations at each stage of tracking 
on the basis of the analysis of consecutive images of ISS, it is 
necessary to carry out a preliminary processing and analysis of 
these images for the purpose of detection and recognition of ISS 
or its nodes and their subsequent binding to the coordinate 
system of the ISS. Starting at a distance of 500 m the task of 
exterior orientation is solved for every single video frame. The 
detection and recognition of details of the ISS and the use of 
their characteristic features is made using computer vision 
methods. The coordinates of reference points the ISS coordinate 
system are measured by using a highly detailed three- 
dimensional model of the ISS. The 3D coordinates are then 
registered to the corresponding positions of these points on the 
image. 
The main property of the problem under consideration is that 
the process of video-assisted docking is performed on a wide 
range of distances starting at 500 m and ending at 0 m. This 
leads to high object appearance changes in the course of 
docking (Figure 1). Because of this property, the detection and 
  
* Corresponding author. 
tracking task must be solved by a set of different algorithms 
depending on the current distance between SCS and ISS and 
this is the reason to use very detailed digital model of the ISS 
including 16000 vertices. Formulas of exterior orientation 
which form the basis for calculation of orientation elements and 
errors of their estimations remain valid in all cases. 
  
Figure 1. The ISS viewed from a distance of 600 m and 30 m 
Another important requirement that defines and restricts the 
choice of algorithms and the sequence in which various 
algorithms must be used is the real-time constraint. 
Measurement should also be highly accurate. In order to meet 
all these prerequisites, the contour-based algorithm was used. 
Its essential characteristics are investigated in this work. In 
order to increase the reliability of orientation parameters 
estimation and ensure pose tracking in real time, the statistical 
treatment of the resulting time series were also used; the ones 
allowing to obtain statistically validated forecasts.