Topic:
What rules restrict survey origins, and what are their disk-space implications?

Description:
When seismic data is loaded, there are three sets of numbers which act as the
lowest cdp/line pair:
1.) The survey origin, set in the top right of the Data Manager > Load seismic >
    Define storage menu.
2.) The lowest cdp/line pair used when three points (x/y or lat/long pairs) are
    inserted to define a survey.
3.) The first cdp and line actually loaded.
 
This document discusses the relationship between those three issues, and the way
they affect the amount of disk space needed to store seismic data.
 

Solution:
GeoFrame 3.5 does not place any restrictions on those numbers, and does not
use more disk space because of the factors below:

1.) You can load a cdp which is less than the survey origin cdp, and a line
    which is less than the survey origin line. You will receive a warning
    message, but data loads, displays in SeisDV, and displays in Basemap with no
    problem.
2.) You can define the 3 corner points to have cdp's less than the survey origin
    and again, everything loads fine.
3.) The x/y or lat/long you load, stay with the cdp/line for which they were
    loaded.  If you add data which is outside the range of cdp's or lines you
    used in defining the survey everything is properly extrapolated.
4.) Disk space for seismic data is allocated only for data which is actually
    loaded.  Thus, if the three points which define the survey x/y span 1000
    cdp's and 1000 lines, and you actually load only 10 cdp's of 10 lines, disk
    space is allocated for 100 traces (10 lines x 10 cdp's), not 1,000,000
    traces (1000 lines x 1000 cdp's).  




Last Modified on: 07-APR-00