Three Simple Models: Acquire 2-D Lines
In the previous chapter, we developed three simple models and used them to generate single shot gathers and images of rays and wavefronts. In this chapter, we use the same models to acquired 2-D lines of seismic data.
Script acql.sh acquires seismic data over model modell.dat, generated by script modell.sh (Section 4.2). The survey layout:
40 shots (line 28)
Shots are equally spaced at 50m intervals (line 32 and line 35)
60 split-spread traces are recorded from each shot location (line 42)
Geophone spacing is 50m (line 46 and line 49)
Geophone offsets range from −1475 m to +1475 m (line 52)
Shot locations range from 2 km to 3.95 km (line 68)
Geophone locations range from 0.525 km to 5.425 km (line 68)
The final data set has 2400 traces (40 shots x 60 geophones per shot). The generation of this data set took about half an hour on a Sun UltraSPARC III with four processors.
Lines 61 and 62 write variable values to the screen. Notice that line 4 is commented out. We find that once a script is perfected, the messages from line 4 interfere with reading the values printed to the screen by lines 61 and 62.
Previously (Section 4.5), we discussed variables nangle (the number of rays or angles that emanate from the source), fangle (the first angle of the fan of rays that emanate from the source), and langte (the last angle of the fan of rays that emanate from the