Unlike the other members of the Field Geophysics Software Suite, the Section Window in GravMag is interactive. You can directly alter your model here.
Depending on what data windows are open, the section window can have as many as three panes: a magnetics profile, a gravity profile, and the cross section under the profile.
Cross-section pane (at the bottom or the entire window if no data windows open, above) shows the different bodies being used, colored and labelled as determined in the Model Window. When the New button is off (just above the section), clicking on a body highlights its vertices and selects it in the Model Window. At that point the body can be dragged around on the section (clicking down on the body and then moving the mouse) or moved using arrow keys. Clicking on a vertex allows that vertex to be moved (again by dragging it with the mouse or using the arrow keys); the vertex becomes hollow to indicate that it is being edited. In v2.1 and later, you can then shift-click on additional vertices so that multiple vertices can be moved together. Changes to a body's shape are reflected in any gravity or magnetic profiles when the mouse is released or with each keystroke.
When the New button is on, the cursor changes to a crosshairs and the button is renamed Done. Clicking in the cross-section will start a new body; each succeeding click adds a vertex until either the first point is clicked a second time, a point is double-clicked, or the Done button is clicked. The initial parameters for the body are defaults of a density of 0.1 g/cc, 0.001 cgs susceptibility, and a remanence of 0.0001 in cgs units pointed parallel to the current field direction. These can be changed in the Model Window. After the body is created, the Done button returns to being the New button.
Next to the New button are the left, top, and right edit fields, the bottom edit field is at the bottom (except in pre-v1.0.14). You can change the edges of the plots in the window by changing these values. Changes take effect when you tab out of the box or select another element of the window.
The position of the cursor on the cross section is shown at the lower left of the cross section pane with the horizontal distance and height (so distance down is negative) when you are editing a vertex.
Gravity and magnetics panes are similar in that they show the values calculated from the current model with stars and those observed as triangles. These panes are only visible when their data windows are open. For the magnetics pane, the values shown are those selected in the popup menu in that window.
You can adjust the size of a pane by moving the gray bar (separator) between it and the pane above or below (the cursor becomes a double line with arrows on either side). The window as a whole can be copied to the clipboard from the Copy item in the Edit Menu, printed using the Print command in the File menu, or saved as a bitmap graphic image using the Save As... command in the File menu. (Printing to a pdf on a Mac will yield the highest quality graphic file). Note that on a PC, removing the suffix when renaming the graphic file when saving might make the file difficult to use; renaming the file and then selecting the file format from the popup list will prevent this problem.
v. 1.0.14 improvements:
You can now adjust the top limit on the section plot. The positions of the observed points are now shown with x's (gravity) and +'s (magnetics). You can now see all of the points and bodies in your profile by clicking on the Show All button in the lower right of the window.