## 3-D two-point ray tracing in pictures

**Petr Bulant**
### Introduction

Two-point ray tracing carried out by means of the CRT program
is controlled by many numerical parameters.
To approach the optimum set of parameters is important and
sometimes complex task.
To plot the normalized ray parameters at the normalized ray domain,
the decomposition of the normalized ray domain into homogeneous triangles,
or the distribution of the ray endpoints,
homogeneous triangles, and receivers at the reference surface
may be very useful for the selection of the optimum numerical
parameters controlling the shooting algorithm.
Program RPPLOT has thus recently been developed to generate
PostScript files with figures of the normalized ray domain
and reference surface containing the above mentioned information.
Program RPPLOT is designed as a post processing program to the CRT
program.

This brief paper would like to illustrate the usage of the RPPLOT
program on the example of two-point ray tracing in the model
with a lenticular inclusion (Klimes 1995).
The example has been presented as a poster at the EAGE
conference (Bulant 1997) in order to explain the shooting algorithm
(Bulant 1996a,b).

The data for this computation may be found in the
subdirectory `len` of the CRT package.
To repeat the computation and to generate Figures 2,4,5,6,7,
run program `crt.for` with main input data file `len-crt.dat`,
and then program `rpplot.for` with main input data files
`len-rp2.dat`, `len-rp4.dat`, ..., `len-rp7.dat`,
respectively.

### Whole paper

The
image of the paper in GIF 150dpi (368 kB)
is designed for an instant screen preview.

The paper is available in
PostScript (8932 kB !, colour figures)
and GZIPped PostScript (2067 kB !, colour figures).

In: Seismic Waves in Complex 3-D Structures, Report 6,
pp. 63-70, Dep. Geophys., Charles Univ., Prague, 1997.

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