Description of the 3D HAS (Horizon ASCII) File Format
The 3D HAS (Horizon ASCII) format is written with header lines describing
the horizon data contained in the body of the file. The ASCII file is
a columnar format. The file is delimited using spaces. (Not Tabs).
Horizons for one of more 3D areas may be written to the file. An identifying
line introduces each 3D. An end statement terminates the data section
for each 3D.
Header section
The first line of file contains the number of horizons written to this data
file, followed by a space and the null value used in this file (must match
exactly).
Next is the horizon list, which uses one line for
each horizon with white space separating each field.
Format - Horizon name, a mnemonic
representing the event, and a color used to draw the horizon in seismic
displays.
Event Types - P = Peak, T
= Trough, Z = Zero Crossing.
Data records section
The horizon list is followed by the name of the first 3D data area.
Format - The mnemonic "#3D_GRIDNAME" followed by a space and
the 3D data area name. Do not use spaces in the 3D data name.
The data records are written in columnar ASCII. Spaces are used to separate
the fields. A separate line is used for each In-line/Xline location. The
file may be decimated to reduce file size.
Format - In-line Xline
UTMX UTMY
followed by columns for Z Values.
A column will be written for each horizon listed in the HAS header.
Data is written in ascending order sorted by In-line then Xline. The Null
Value is written for each missing value (no pick). In-line and Xline numbers
must be integers. All other values may be decimals. Times are written
in milliseconds.
End of file section
The last In-line/Xline data record for each 3D is followed by a terminator
line.