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Let us assume that reflecting interface i is given through two
points belonging to it, A and B. Since traveltimes are
computed independently for each CMP, we use a coordinate system
with the origin in the midpoint between source and receiver (both located at
the surface). In this CMPcentric coordinate system, interface i can
be expressed as
 
(1) 
where is the dip of the interface:
 
(2) 
and d_{i} is the distance from the CMP point to the
interface:
 
(3) 
Figure shows a threeinterface example.
peglegmodel
Figure 1 Three interface reflectivity model
for illustrating the meaning of the notations d_{i} and . Notice the sign convention for angles.

 
Similar to Levin and Shah (1977), we use the method of images to compute
traveltimes. Let us denote with the image of
point through reflector
i (see Figure ). Through simple analytical geometry we find that
 
(4) 
imex
Figure 2 Image point concept
illustration.

 
Next: Cascading imageconstruction operations
Up: Liner and Vlad: Multiple
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Stanford Exploration Project
10/23/2004