2.1.2. Sections: the editing canvas

Cross-sections are the editing surface of StrixGeo. You pick a slice through the project, see the investigations projected onto it, and draw or edit the model between them. The edits commit to the model, not to the section, because the section is a view. A section shows the full classification of every test in its corridor, automatically: the classification lives on the test, so it appears wherever the test appears.

2.1.2.1. The section view

On a section you can work on any of the three model levels by switching the axis (stratigraphic, litho, geotech). You see the column logs at each test, the correlations you have drawn, and the partition fill (bands, onlaps and lenses) that the 2 / 1 / 0 rule produces. That rule is explained in the Litho chapter, where it first does its work. Two view controls scale the drawing:

  • a vertical exaggeration control, to stretch the depth axis so thin layers are readable;

  • a column-spacing control, to spread the tests out horizontally.

Every overlay is drawn in the exaggerated, spacing-adjusted space, so what you edit is what you see.

A section has a corridor, a half-width to each side of the line, and every investigation within that distance projects onto the section. The corridor is always greater than zero; a wider corridor pulls in more tests, a narrow one fewer.

2.1.2.2. Tie-sections

A set of roughly parallel sections describes the ground along its lines, but says nothing about how those lines relate where they would cross. A tie-section fixes that: it is a cross-section drawn across the parallel sections, connecting one test on each of them, so the interpretation stays consistent from one line to the next. StrixGeo can suggest tie-sections for you, sweeping the tests in order and proposing rungs that connect the parallel lines without crossing each other or reusing a test; you accept the ones you want.

A tie-section is not a special kind of object. Once accepted it is an ordinary cross-section, drawn and edited like any other. Its value is that it runs across the grain of the parallel sections, and that matters just before the 3-D build: when StrixGeo fills the space between sections (explained in the Litho chapter), it blends the two nearest sections at each point, and a tie-section gives it material to blend across the parallel lines rather than only along them.

2.1.2.3. The PDF sheet

The cross-section PDF sheet is a landscape drawing sheet, drawn by the app itself and printed to PDF through the app’s own print path. Because the preview in the dialog and the printed PDF are the same drawing, there is no surprise between screen and paper.

What the sheet shows:

  • the profile, the partition you drew, with the fill continuous across the columns, coloured by unit (on the geotech axis, by packing class);

  • the column logs at each test;

  • a map to the side of the profile, with the section line, the tests, a scale bar and a north arrow;

  • a legend of the units;

  • free text fields and a title block.

The sheet offers two ways to set the scale:

  • Fit, where StrixGeo fits the drawn profile to the sheet. Because the sheet keeps its height and grows in width, a long thin section fits by growing the page width rather than shrinking the profile.

  • Explicit, where you set a horizontal and a vertical scale yourself (and can drive the exaggeration and spacing from the app’s own sliders), so the sheet prints at a defined, reportable scale.

You can play with the exaggeration and spacing live in the preview and then export; the sheet is the same drawing either way.

You export a drawn section, with its corridor, at the location you chose. Slicing the finished 3-D model along a single zero-width line and exporting just that slice is a different thing, and it is future work.