OASIS MONTAJ
All GM-SYS distributions include a suite of GXs for building, modifying , opening, and plotting GM-SYS models from within Oasis montaj. Load the Oasis menu file gmsys.omn to access these functions. If Oasis montaj is detected on the target system during installation of GM-SYS, you will have the option of installing these files.
When models are opened using these GXs, a link is established to communicate cursor position and other information between GM-SYS and Oasis montaj. Two buttons on the GM-SYS toolbar control whether
cursor tracking is always active, occurs only on a mouse click, or is disabled.
Notes:
1) Each time a model is opened from within OASIS montaj, a new instance of GM-SYS is started. The
New Model and Open Model functions in these in-
stances of GM-SYS are disabled.
2) Cursor tracking and all included GM-SYS GXs are designed to work with the OASIS montaj Free Interface version.
GM-SYS Modeling and OASIS montaj
10.1 BUILDING GM-SYS MODELS
WITHIN OASIS MONTAJ
Under the New Model submenu of the GM-SYS Menu, there are four methods for building new mod- els from within Oasis montaj; two build models from databases, one method builds models from grids along a digitized profile, and a fourth option copies or “clones” an exisiting model.
1) From current mark... builds a model from the cur-
rent line in the current database. This option expects some portion of the current line in the database to be “marked” or highlighted. The “mark” designates a range of fiducials or locations which will be used to build the GM-SYS profile and does not determine which channel(s) are used. (Hint: You can select all of the data in a line by double-clicking on any chan- nel header).
2) From map profile... can extract model horizons,
data, and topography from specified grids along a digitized profile. Grids may have differing projec- tions and distance units.
3) From selected database lines... builds one or more
models from the selected lines in a database. It does not utilize “marked” data.
These first three options provide dialogs from which you may elect to include observed data, station el- evations, and topography. Additional dialogs allow you to include known horizons, and measured or calculated gradient data in your models. Your new model will inherit the projection information from the database or the first grid sampled, depending upon the method you use.
Note: These techniques generate an intermediate
XYZ file (<modelname>_gms.xyz), and a BATCH file (<modelname>_xyzgms_cmd.bat). XYZGMS is then used to generate the new GM-SYS model files (See Section 9).
XYZGMS will convert multi-segment profiles into a single-segment profile as shown on the fac- ing page. The black line represents the original profile as specified 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.
4) Clone an exisiting model... copies the model struc-
ture of an existing model to a new location, specified by digitizing an origin and a second point to deter- mine azimuth. New gravity and magnetic data may be extracted from specified grids at the new loca- tion. This method can not substitute new topogra- phy, due to the possible complexity of intersecting surfaces, but you may import and merge a new topo- graphic surface once you’ve opened the model in GM-SYS.
The fifth option, New blank model..., starts GM-SYS with no model loaded. Cursor tracking (see Section 10.3) is not enabled in this case.
10.2 WORKING WITH EXISTING
MODELS WITHIN OASIS MONTAJ
Use the Existing model submenu to open, modify, copy, or plot the location of an existing model in your workspace. You may open an existing model for ed- iting within GM-SYS by selecting the Open a
model... option. Selecting Add data to model... al-
lows you to add or replace observed data in an exist- ing model. Clone an existing model..., described in the previous section, duplicates an existing model and extracts new data. Plot model location... can plot the profile trace, gravity station locations, or mag- netic station locations of an existing model on a Geosoft map, based on a selected View within the model. Plot model Plan View... allows you to select any saved View in a model and the plot the Plan View to a Geosoft map,
10.3 CURSOR TRACKING
When a GM-SYS model is created from a database, from grids, or from an XYZ file, a coordinate trans- formation is written into the .ECS file that translates between GM-SYS “profile” (X,Z) coordinates and “real world” (X,Y,Z) coordinates. A dynamic inter- face allows GM-SYS to send the (X,Y,Z) coordinates of the cursor to OASIS montaj and have them dis-
played as a linked cursor within the databases and maps. The cursor will track correctly in 3-D maps when the 3D Viewer is active. If projection infor- mation is associated with the X and Y channels in the source database or with the grids from which the model was created, the projection information will be stored in the .ECS file and will be used to cor- rectly project the coordinates reported by GM-SYS to OASIS montaj.
Two buttons in the GM-SYS toolbar control how the cursor position is relayed to OASIS montaj. Press- ing the left button (default) allows constant report- ing of the cursor position to OASIS montaj. Press- ing the right button causes GM-SYS to report the cursor position only on a mouse click. You may elect to deselect both buttons, which prevents GM-SYS from sending cursor coordinates to OASIS montaj.
10.3 LOADING GM-SYS PLOTS
INTO GEOSOFT MAPS
To generate a Geosoft-compatible plot from GM-SYS, just select the “Geosoft Driver” as the printer selection in the GM-SYS printer setup. This will generate a Geosoft “.PLT” file that can be loaded into a Geosoft Map. Patterns do not translate but are displayed as the solid foreground color.