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Transformation Scripts

The script contains one line starting with the
letter 'p' and arbitrary many lines starting with 'o'.
o-lines are read one for each input frame. If there
are input images available while there are no more
'o'-lines left, the script is reread from the start.
To accomplish a conversion with fixed parameters 
we therefor need just a two-line script for
arbitrary many frames.

'p'-lines describe target format and 'o'-lines 
source format in 'insert'-mode. The roles are
reversed in 'extract'-mode.


p f1 w320 h300 v180  C0,320,0,240 
o f3 r-2.5 p12 y0 v173

In this case we remap frames made with a fisheye lens 
(f3) with 173° field-of-view (v173) to cylinder format (f1)
with 180° field-of-view (v180). We rotate the images by 
-2.5° (r-2.5), and tilt by 12° (p12). The target frames 
are 320x240 pixels large and cropped from a 320x300 pixel 
size (w320 h300  C0,320,0,240). This cropping simulates 
a shift lens straightening vertical lines.

The roles of o- and p-lines are reversed in 'extract'-mode.
The input-frames are characterized by the single p-line, 
while each outputframe corresponds to one o-line. Again, 
if there are fewer o-lines than frames, the script is
restarted. This mode is better suited for extracting 
virtual camera moves, see examples below. The pan/tilt/rotation 
parameters can be deduced by viewing source frames 
with PTViewer.

Options in the script are specified by an identifying letter 
followed by the value of the corresponding option. 
This is a list of supported options. 

f           Projection  format, one of 
                 0 (rectilinear)
                 1 (cylinder)
                 2 (equirectangular in p-, fisheye in o-line) 
                 3 (fisheye-equidistant)
                 4 (equirectangular)
                10 (fisheye-equisolid) 
w           Width in pixel, required only for destination image
h           Height in pixel, required only for destination pixel
v           Horizontal field of view angle (in degrees).
y           Yaw (pan) angle in degrees (o-line only).
p           Pitch (tilt) angle in degrees (o-line only).
r           Rotation in degrees (o-line only).
a,b,c       Radial distortion parameters. Pixels are 
            shifted radially according to a third order
            polynomial with coefficients a,b,c (o-line only).
d,e         horizontal and vertical shift (in pixels) (o-line only).
g,t         horizontal and vertical shear (in pixels) (o-line only).
C           Crop rectangle, left,right,top,bottom pixelposition 
            (comma-separated, default: no crop).
n           Name, usually ignored except if "skip" (= skip frame) 
            and "same" (= use previous frame again) (o-line only).

Specifying per-frame transformation parameters is tedious. A few 
standard options are therefor implemented as macros which are 
expanded by the build-in preprocessor

LOOP(n)     Repeat the following block in brackets n-times.

o f0 v70 w640 h480 y10
o f0 v70 w640 h480 y11
o f0 v70 w640 h480 y12
o f0 v70 w640 h480 y11
repeates these 4 lines 100-times. Please use brackets 
exactly as shown.

SPLINE(n1,n2,...)   Connects start, intermediate and 
           end values of pan, tilt, rotation and zoom 
           level using a smooth spline function with 
           specified number of frames. 
o f0 v70 w640 h480 y0 p0 r0
o f0 v75 w640 h480 y10 p5 r6
o f0 v60 w640 h480 y20 p10 r10
o f0 v55 w640 h480 y30 p30 r5
o f0 v50 w640 h480 y50 p10 r3

In this example we start with the first o-line, then 
use 30 frames to smoothly move to the second o-line, 
then 100 frames to the third, etc. Any number of 
intermediate points may be connected by the spline.

GRID(p1,p2,np,yl,yr,nh) Create a grid of prerendered 
          images for use in object viewer. 
          p1,p2 - pitch down/up
          np -number of pitch positions.
          y1,y2 - yaw left/right.
          nh -number of yaw positions.

p f2 v360
o f0 w180 h120 v75 r0 y0 p0 

Using 'extract'-mode, this script creates
37x72 frames with 5 degrees spacing vertically
and horizontally which cover the full spherical
view. They can be used to display panoramic
views in Object-viewers.
SKIP(n)   Skips n frames.

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