************************************************************

    SOFA - SEQUENCES FOR OPTICAL FLOW ANALYSIS
    SYNTHETIC TEST SEQUENCES WITH FULL GROUND TRUTH

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Emanuele Trucco and Ioannis Lalos
Computer Vision Group and Ocean Systems Laboratory

Dept of Computing and Electrical Engineering
Heriot-Watt University

April 1998


DISCLAIMER. All the data and information in this package are supplied
        "as is". No guarantee is given on their accuracy, completeness,
        or correctness. No responsibility can be accepted for damages,
        losses or any other situation caused directly or indirectly
        by the use of this package.


You can use it and redistribute SOFA at will, but *PLEASE REMEMBER*:

a) IF YOU PUBLISH RESULTS obtained by processing SOFA data,
   please include the acknowledgment "SOFA synthetic sequences courtesy
   of the Computer Vision Group, Heriot-Watt University
      (http://www.cee.hw.ac.uk/~mtc/sofa)".

b) IF YOU REDISTRIBUTE SOFA, please make sure that this README
   file is included AND READ.


For information, problems, etc, contact Emanuele Trucco (mtc@cee.hw.ac.uk)

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1) FILES
--------

In this directory there are the following files:

  I)   S1README - this text file.

  II)  S1img1.gif
       S1img2.gif
	.
	.
	.
       S1img20.gif - sequence of images in .gif format 

  III) S1orth1.gif
       S1orth2.gif
       S1orth3.gif - 3 orthographic projections of the scene indicating the 
                     size and the position of the scene in the world reference
		     frame (.gif format)

  IV) S1opfl.gif - the 10th image together with its optical flow (.gif format)



2) INTRINSIC PARAMETERS
-----------------------

Image size in pixels = (256 x 256) 
Focal length = 5.000000 (in world units)
Pixels per unit on Y-axis  = 61.803860 
Pixels per unit on X-axis  = 61.803860 
Image centre in pixels = (127.000000 x 127.000000)



3) SCENE & WORLD REFERENCE FRAME
--------------------------------
 
The scene contains one cylinder and a cube.
Cylinder radius = 30 world units
Cylinder height = 10  world units
Cylinder segments = 20
Cube side = 20 world units

The World reference frame (Xw,Yw,Zw) is a right-handed system and its origin 
(0,0,0) lies in the centre of the cylinder.

For more information you may view the images in the following files : 
S1orth1.gif, S1orth2.gif, S1orth3.gif



4) CAMERA
---------

A Perspective Camera is used for taking different snapshots of the scene.
The camera is moving in a circle route on a plane perpendicular to the Yw-axis 
and always points towards the world origin.

The initial rotation matrix of the camera is given with respect to the default
camera reference frame. 

The default camera reference frame has the same origin as the world reference
frame but it is rotated 180 degrees around the Yw-axis,i.e.

              Yc = Yw, Xc = -Xw, Zc = -Zw.

(NB: c=camera reference frame, w=world reference frame)



5) LIGHTS
---------

There is one static light in the scene. Its location is (55, 50, 20)w and it
radiates light equally in all directions.



6) EXTRINSIC PARAMETERS
-----------------------

Initial position of centre of projection : (70.000000, 50.000000, 0.000000)w

Initial camera rotation with respect to the default camera reference frame:
I)
By angle: 1.664065 (in radians)     -     95.343880 (in degrees)
around the unit vector : (-0.291888, 0.910825, 0.291888)w

II)
Rotation matrix :  0.000000  0.000000  -1.000000  0.000000
                  -0.581238  0.813733   0.000000  0.000000
                   0.813733  0.581238   0.000000  0.000000
                   0.000000  0.000000   0.000000  1.000000


6.1) Motion information
-----------------------

The camera is moving in front of the stationary scene.

-  Camera Translation : | Yw = 50
		        | Xw = R*cos(theta)
		        | Zw = R*sin(theta)

   where theta=0,2,4,6,...,38,40 degrees
   and R = 70 world units

-  Rotational velocity :  fixed axis of rotation: Yw-axis (0,1,0)
			  velocity = 2 degrees per frame 


7) ACKNOWLEDGEMENTS
-------------------

We would like to thank Tiziana Aicardi of the department of Physics,
University of Genova (Italy) for providing Andrea Giachetti's optical flow 
tool ('flowtool') which was used for the creation of the optical flow image 
(S1opfl.gif).