Topic:
How do you load 2D segy with non-integer sp increments?

Description:
I thought that IESX was not able to read non-integer shot point increments
from the trace header.
 
Is it the same with IESX.11?

Solution:
IESX has always been able to read non-integer shotpoints from the trace headers.
  
It then determines the required increment from the values encountered.  Every 
trace must have a UNIQUE SP number in the header.  Non-integer and varying SP 
increments can be loaded this way.
 
However by default it reads the SP from the header as IBM (32 bit Integer). 
This format was defined by the SEGY standard for SP numbers, but does not 
accomodate non-integer SP numbers.  It has become common for processing 
companies to "workaround" this SEGY definition by putting the SP in the headers
as: 1. IBM (flt.pt.), or 2. IEEE (flt.pt.), or 3. multiplying the SP by 1000 so
that 101.5 becomes 101500 and can be stored in the IBM (32 bit Integer) format.
 
IESX can load any of these above situations directly from the header.
 
1.) Set the shotpoint header format to IBM (flt.pt.)
 
2.) Set the shotpoint header format to IEEE (flt.pt.)
 
3.) Set the shotpoint header format to IBM (32 bit Integer), the Key parameter
    source: SP > Expression and define an expression SP = SP/1000.
 
What has changed with IESX.11 is that the SEGY Dump utility will now allow you 
to view header locations that are stored in non-standard format such as IBM
(flt.pt.) or IEEE (flt. pt.).  To read these values in SEGY Dump enter the SEGY 
Dump panel then enter the new option: Trace header locations... and set your
formats here.  These locations will be displayed at the beginning of each trace
dump.




Last Modified on: 25-NOV-98