General remarks on the SW3D software

Remarks concerning Fortran compilers

Some Fortran compilers (like Linux g77 ver.0.5.20, Linux fort77 ver.1.13, or very old HP-UX (ver.8) or Apple Macintosh compilers) do not adhere to the ANSI Fortran 77 standard to that extent they could correctly compile packages like MODEL or CRT (they incorrectly compile DO loops). HP-UX ver.10.20 compiler fort77 does not compile all programs correctly (problems with names of subroutines). Note that Linux compiler g77 ver.0.5.23 or ver.2.90.23 (980102) already compiles DO loops correctly and is used by the authors (option -O is not recommended). Linux fort77 ver.1.14a also compiles DO loops correctly but has other problems. Linux compiler g77 ver.0.5.24 or ver.2.91.66 (981002) (and many other versions) does not write files to unit 6 correctly. The authors use compilers by Lahey under MS-DOS.

Perl scripts

Perl scripts are used to control the compilation of the Fortran code, to run the programs according to the history files and sometimes to complete some system-dependent tasks.

Perl interpreter is usually a part of the Unix installation and is available for most other operating systems. Perl interpreter should be available at


Plotting programs generate 2-D plots (e.g., synthetic seismograms) in PostScript. The figures may be printed on any PostScript printer, viewed on the screen, included into papers, etc. There are also several PostScript figures on the compact disk. To view the figures on the screen, it is not bad to have installed a PostScript viewer and to enable it in the HTML browser as a helper. The authors use GhostScript or GhostView.

VRML browsers

Virtual Reality Modeling Language (VRML) is a powerful tool to display 3-D models, rays and other 3-D objects relevant to seismic modelling. In particular, we recommend VRML97 (Virtual Reality Modeling Language ISO/IEC 14772). Packages FORMS and MODEL are equipped with the programs to triangulate structural interfaces and velocity sections and display them together with rays and source and receiver points in 3-D by means of VRML. The compact disk contains examples of generated VRML files.

To see the VRML files, it is recommended to have installed a VRML97 browser and enable it in the HTML browser as a helper. If you have no VRML97 browser, please, ask your system administrator to install one for you. Unfortunately, many presently available browsers support just VRML version 1.0C or have severe bugs. The authors have no access to Silicon Graphics computers, where they might expect good VRML97 browsers. Under Linux, they succeded to install and use browser vrmlview. However, it has several bugs which may be fixed in future versions. For example, the ambient light in "vrmlview" makes all objects white, so it cannot be used. The ambient light is thus poorly simulated by sets of directional lights on this CD-ROM.


Visualization software GOCAD (Geological Object Computer Aided Design) is a product of the GOCAD consortium. GOCAD is an integrated and geologically oriented CAD software that provides various tools to construct a wide range of earth models, for application in geology, geophysics and reservoir engineering. GOCAD has been developed for many operating systems (see T-Surf). Packages FORMS and MODEL are equipped with the programs for conversion of points, lines, triangulated surfaces and 3-D grid of points into GOCAD. The compact disk contains examples of generated GOCAD files.

For the discussion how to display 3-D seismic models through the VRML and GOCAD refer to Bucha (2001).


Bucha, V.: Displaying 3-D seismic models through the VRML and GOCAD. In: Seismic Waves in Complex 3-D Structures, Report 11, pp. 337-355, Dep. Geophys., Charles Univ., Prague, 2001.