Mansour,
Sorry, I spoke too soon last time. The actual format of your data is GSC
grid. This would be another good candidate for a conversion routine. I
believe there is a free grid viewer available from them, but I don't know
about a converter.
Does anyone else know of a converter? Maybe try calling someone there, they
use Geosoft so must have a converter of their own.
If it is any help, here is a description of the format from Appendix C of
the standard GSC RFP document.
Good luck
Marc
3.5.2.2.2 Grid archive:
See ANNEX "A" for grid cell size
The grid must be oriented in a north-south direction regardless of flight
line orientation. The grid will be sorted by columns (south to north) from
west to east. Example: an area with 200 rows and 300 columns. The grid
archive would read 200 rows of column 1, then 200 rows of column 2,
......200 rows of column 300.
NOTE: All data should be submitted in its proper UTM zone. Since the
survey area straddles two separate UTM zones, the contractor is requested
to provide two UTM projections of each parameter to simplify the process.
The Technical Inspector must be consulted prior to archive generation.
For any map sheet or area, the number of grid values per row and column
must be constant for that map sheet or area (i.e. a full rectangle of
gridded data). This infers the following:
(i) As the UTM projection of a map sheet boundary is not a true rectangle,
the grid boundary must be a rectangle which encloses the four map sheet
corners.
(ii) If any grid point cannot be given an interpolated value, then a null
value (-9999.000) must be assigned to that grid point.
(iii) To ensure exact matching of contoured maps the grid must extend by at
least 5 grid points beyond the smallest rectangle which contains the map
sheet corners. If more than one grid is required each grid must have a
common origin, to ensure that all grids may be merged back together.
File Contents:
Each file must have (i) a header, and (ii) the gridded data.
Header:
Record No. 1 - area identification by area name, NTS map sheet number if
applicable, geophysical series number, survey year, flight altitude.
Format (A80)
Record No. 2 - central meridian (decimal degrees).
- southern parallel (decimal degrees).
- northern parallel (decimal degrees).
- projection; UTM_NAD83
- grid cell size in metres.
- number of coordinate pairs defining area.
- predominant flight line direction in degrees from north.
- rotation angle of grid, if applicable, usually 0.
- data unit (e.g. nT).
Format (3F10.5, A10, F10.2, 2I5, F10.3, A10)
Record No. 3 - sequence of latitudes and longitude pairs (decimal degrees)
for coordinates defining area beginning with the southwestern corner,
proceeding clockwise.
Format (8F10.5)
Record No. 4 - equatorial radius.
- eccentricity of ellipsoid.
- latitude of projection origin (decimal degrees) 0 for UTM
- scaling factor along a parallel.
- geoid select NAD27 or NAD83. (For this area use NAD83)
Format (F10.2, F10.8, 2F10.5, A5).
Record No. 5 - grid origin described by the number of grid cell columns in
east direction with respect to projection origin.
- grid limits described by number of grid cell columns in east direction
with respect to projection origin.
- grid origin described by the number of grid cell rows in north direction
with respect to projection origin.
- grid limits described by number of grid cell rows in north direction with
respect to projection origin.
- number of grid cell rows.
- number of grid cell columns.
Format (6I10)
Data:
The above must be followed by a string of grid values, a column at a time,
that is, each column will begin a new record:
e.g., WRITE(,) (GRID(IROW, ICOL),IROW=1,NCROWS)
(Format (8F10.3))
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Data Donkey - Geophysical Data Processing, Consulting and Software Development
Creator of the POWER TOOLBOX utilities for OASIS montaj
contact: mailto:[EMAIL PROTECTED] tel (306) 931-6853 or
http://www.datadonkey.com
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