Grid Profile

Use the Grid and Image > Utilities > Grid Profile menu option (GRIDPROF GX) to extract a data profile from up to five grids and place them in a new line of the current database. If a database is not open, you will be prompted to either create one or select an existing one. This capability can be useful for a variety of applications including modeling and removing local trends during gridding.

Grid Profile dialog options

Grid1	The name of the grid file from which to extract the profile. Script Parameter: GRIDPROF.GRID1
Grid2	The name of the grid file from which to extract the profile. Script Parameter: GRIDPROF.GRID2
Grid3	The name of the grid file from which to extract the profile. Script Parameter: GRIDPROF.GRID3
Grid4	The name of the grid file from which to extract the profile. Script Parameter: GRIDPROF.GRID4
Grid5	The name of the grid file from which to extract the profile. Script Parameter: GRIDPROF.GRID5
New line name	The name of the database line in which to place the profile. If the line does not exist, it will be created. If it does exist, the X, Y and grid channels will be created. The line number should be preceded by the line type (L – normal line, B - base line, T - tie line, R - trend line, S - special line, or D - random point line). Default type is "S" See the Application Notes below. Script Parameter: GRIDPROF.LINE
Sample interval	The interval along the profile trace at which to sample the grid. Script Parameter: GRIDPROF.SAMPLE
Method to set profile coordinates	Select the method to set profile coordinates "digitise from map" or one of the "manual input" methods. Depending on your method to set profile coordinates you will either have the Profile Coordinates dialog displayed, which requires manual entry of data points, or the Extract Profile dialog will be displayed. This dialog enables you to interactively select your profile points from the displayed grid. Select OK to begin digitizing and then right-click and select Done. Profiles may be defined interactively, using the digitizing tool, or manually, by specifying up to 5 X and Y positions. In the digitizing option, enter consecutive end points by locating the mouse cursor and pressing the left mouse button at each point. Press the right mouse button to complete the profile definition. Only manually defined locations may be used when GRIDPROF is run as a script (see the note below). The profile defined is then placed in the specified line in the current database. A grid profile channel is created as "G_<channel name>" where "<channel name>" is the name of the grid the profile was extracted from. See the Projections section below for an explanation on how projections are handled for each of the methods. Script Parameter: GRIDPROF.METHOD: 0: Digitizing, 1: Manual Input; 2: Manual Input – map coordinates.

Application Notes

Projections

Care must be taken when choosing between the digitizing methods. Both the "digitise from map" and "manual input – map coordinates" methods assume that the entered locations are given in map coordinates. Because the database X and Y channels may have a different projection than the current map data view, the X and Y locations written to the database may be different from those digitised or entered manually. However, the shadow cursor should map between the two faithfully, and a line path drawn on the map from the database profile should match the locations entered from the map. The "manual input" method assumes that the coordinates are given in terms of locations in the current X and Y channels. If the X and Y channels do not have a projection defined, then the X, Y channel projection is set to be that of the first grid. In either case, the values displayed are the same as those expected from the entered values.

Implement Local Trended Gridding

The bi-directional gridding algorithm (BIGRID) enables you to grid using local trend lines and removes local effects that can degrade the quality of final maps. The basic procedure is to extract a profile from the grid you are working with, convert it to a trend line, and then run the Bi-directional gridding option.

1. Once the profile has been extracted (GRIDPROF GX) and the line created in the database, scroll to the new line and select the ID Cell for the line: right-click and select Edit from the popup menu.

2. In the Edit Line dialog, change the line type to "TREND" and click OK.

3. Now, run the Bi-directional Gridding option. The system will include the local trend line in the gridding process.

Running GRIDPROF as a Script

This GX may now be run as a script; however, the profile positions must be entered using the "manual" option. Points entered using the "digitizing" option are not stored as script parameters. Up to five locations may be entered.

Existing lines in the database will be overwritten. (There is a warning prompt in interactive mode.)