XYZGMS

XYZGMS is a command-line driven GM‑SYS utility program that reads GEOSOFT format 'XYZ' files with several fields of data and creates a GM‑SYS Profile model. Input data fields may include topography, additional global horizons, gravity data, magnetic data and station elevations. It is typically called by a model-building GX in Oasis montaj.

Application Notes

XYZGMS reads free format ASCII files, (i.e. fields of data separated by spaces). Data fields can be in any order you chose. Geosoft line headers need to be present. You select which 'Line' will be used for building the model.

Capabilities

  • Window and decimate your data to a subset of your data file
  • Select default values for missing data types (e.g. magnetic station elevations)
  • Create all necessary files for a GM‑SYS model including conveniently recalled views
  • Specify a starting X-coordinate offset

Multi-segment Lines

Note that XYZGMS converts a multi-segment line into a single-segment profile as shown below. The black line represents the original profile as digitised by the user. The red line is the location of the model profile in real-world X,Y space with values projected perpendicularly onto the model profile. The model-profile azimuth is based on the first and last points in the original profile. The profile location is then shifted to minimize the average mis-fit.

image/ebx_1238180856.jpg

The first point in the model will be placed at X=0 (GM‑SYS model coordinates) and GM‑SYS model coordinates will be calculated as the distance from that point. The -x0 parameter may be used to shift the starting X-coordinate to any value. Those coordinates may also be shifted using the GM‑SYS utility program CVTGMS.

Profile Azimuth

XYZGMS calculates the profile azimuth and generates a transformation between the profile (X’Z) coordinates and the original input (XYZ) coordinates. The coordinate transformation is saved in <out>.ECS and is used by GM-SYS Profile Modelling to recover the original XYZ coordinates for surface export, grid output, and interaction with third-party software, such as Geosoft’s Oasis montaj™. XYZGMS assigns relative strike angle=90, magnetic inclination=60, declination=20 and field intensity=56,000 as default values. You may change these for each model in GM-SYS Profile Modelling (Profile menu, set field and set azimuth) to the proper values for your profile.

Example

XYZGMS test test -l=L19 -d=5 -t=400 -eg=400 -zg=5

This example will read data from file test.xyz and create a GM-SYS Profile Modelling model named "test". Only every 5th point will be read, topography elevation is constant at 400 meters, gravity data is in the 5th field of the input data file, and the elevation of the gravity stations is constant at 400 meters.

Sample Files

Two sample files are included with the distribution:

  1. gms.xyz is a sample input data file
  2. sample.bat is a sample batch file using gms.xyz

Specifications

Maximum number of columns (characters) in input record, 256 maximum number of data fields in input file: 50, maximum number of data points in output model: 16,000.

See Also: