GeoProfiler vers. 0.2 help

Plugin creators: M. Alberti and M. Zanieri.
The original concept is by M. Zanieri, while the implementation is by M. Alberti.

geoProfiler purpouse is in helping to create geological profiles, by automating the import of georeferenced data related to topography, geological outcropsm, attitudes and others.

Fig. 1. The module interface, with the various commands expanded.

This experimental module is a successor to qProf, an independent QGIS plugin, whose code has now been largely rewritten and incorporated as the geoProfiler module within qgSurf.

The original qProf plugin will continue to exist but probably only bug-fixes will be applied and no new feature will be added.

geoProfiler is not currently at parity with the qProf functions, lacking a few features. On the other hand, it has more advanced features for the creation of parallel profiles.

The main missing features of the current geoProfiler version with respect to qProf are:
a) no processing for GPX input data is available;
b) no slope calculation is performed.

Two major improvements with respect to qProf are that geological profiles are no longer restricted to straight lines and that parallel profiles can be automatically created by duplicating a source profile trace.

In current version the workflow is segmented into two main parts:

a) the (eventual) creation of the topographic profile (or parallel profiles), that will be stored as a 3D line layer into a geopackage;

b) the incorporation of geological elements (intersections with outcrops and lineaments, projections of quoted point and of geological attitudes) into the topographic profile(s) .

The creation of topographic profiles is accomplished by using the functions provided under the 'Create 3D topographic profiles' tree (Fig. 1). The topographic profile is stored as a 3D line layer into a geopackage.

Loading it (or another 3D line layer created outside the module) into the TOC, allows to use the 'Choose working 3D profiles layer', so that it can be used as the base for the addition of the geological elements.
That is accomplished by using the tools in 'Create geological profile' (Fig. 1).

When needed the user can plot the profile.

Fig. 2. Example of topographic profile with standard parameters. Data: Aster, Southern Italy (Calabria- Lucania boundary, Thyrrenian coast to Ionian coast.

We need to create a 3D line profile, or set of parallel profiles, as the first step, unless created in a previous session (Figs. 2, 3).

Fig. 3. Functions for creating a topographic profile.

When created with this module, the 3D line layer storing the profiles will be saved in a new or already existing geopackage.
The line layer may already exist, so that the new profiles will be appended to the layer. Otherwise, the profiles will be inserted into a new layer.

The profile trace can be loaded from an existing 2D or 3D line layer, using "Load trace from 2D line layer" or can be digitized in the canvas with "Digitize 2D trace in canvas" (Fig. 3). After activating the button, you add a point with a left click, and terminate the line with a right click. It is possible to delete the digitized line by cliking the "Clear last trace" button.

Afterward, we need to define the input DEM that will provide the elevation information for the 3D line layer, by double-clicking on "Define DEM as elevation source", where the user can choose which one of the loaded DEMs to use (Fig. 4).

Fig. 4. Choice of source DEMs.

Having defined both the source profile trace and the DEM, the final step is the generation of the 3D topographic profile, by double-clicking 'Generate 3D profile lines'.


It is possible to define the number of parallel profiles and their lateral spacing (Fig.5). By default, the number is 1, so if you do not define this parameter the plot will consist of just one profile. Otherwise, when creating more than a profile, the number to insert is an odd number (e.g., 3, 5 7 and so on), since the parallel profiles will be at the left and right of the base profile.

This step already allows to plot a profile, that would be a single topographic profile with default parameters (e.g., Fig. 2).

Disposing of a 3D line, previously created with this module tools or created in another way, allows to plot, add geological data, customize the resulting plot.
In order to do this, we must first load this 3D layer within the current QGIS project and afterwards, choose this layer with 'Choose working 3D profiles layer' (Figs. 1, 6).

Fig. 6. The plugin interface for geological data ingestion.

There are various kinds of geological data that can be plotted into profiles. Based on their own geometric nature and the geometric relationship with the profile plane and the topographic line, we can distinguish between data that are constrained to lie in the topographic surface and others that are not linked to the topographic line in the profile.

In the latter case we have simple points (e.g. seismic hypocenters) and plane data with point-like extension at the profile scale (e.g. geological attitudes), that can be projected onto the profile plane irrespective of the topographic profile position.

In the former we have surficial line (e.g., fault traces) and polygonal features (e.g., geological outcrops) that are constrained to the topographic profile. Here we say that these geological features intersect the profile plane at the topography line.

Geological data can be projected on the profile (e.g., points or geological attitudes) or can intersect the profile (e.g., faults, geological outcrops). Geological data are stored in point, line or polygon layers.

In details, these processings can be:

• the projection of points on the profile section;
• the projection of geological attitudes;
• the intersection of geological lines (e.g., faults) on the profile section;
• the intersection of geological polygonal elements (e.g., outcrops) on the profile section.

When considering point data projected onto the profile plane, an obvious example is that of seismological data such as the hypocenters of a seismic sequence.
To plot this kind of data, we need to define the source layer, the field storing the elevation value for each point, the maximum allowed orthogonal distance of the point from the profile plane and the field that will be used to label the points when useful (Fig. 7).

Fig. 7. Example of point projections UI.

By double-clicking the "Plot" item and fine-tuning the plot parameters from the "Graphical parameters" we obtain a profile where the points are plotted normally to the profile plane, with the height extracted by the "Z field"-defined values (Fig. 8).

Fig. 8. Seismic hypocenters of the 2007 Colfiorito sequence (Central Apennines) plotted in a profile with parameters as in Fig. 9.

The case for attitude projections is similar to the point projections but it adds also a local plane-like nature for the projected data.
The source for geological attitudes is therefore still a point layer, but we need also to define the sources for the plane attitude, as given by its dip direction (or strike azimuth, following the Right-Hand-Rule) and the dip angle. Moreover, to limit the distance of the attitudes from the profile plane we set the "Max. profile distance" value and, when labelling data, the chosen "Id" field values will be used.

Fig. 9. Geological attitudes projection UI.

The geological attitudes are projected on the section plane perpendicular to the profile line, and are represented by a marker and a short segment representing the intersection between the geological plane and the profile plane (example in Fig. 10).

Fig. 10. Example of geological attitudes projection along a profile in the eastern sector of Mt. Alpi zone (Basilicata, Southern Italy).

Line intersections is the first of the two cases of intersections between features and profile plane. Line features, such as the surficial traces of faults, plot as points lying on the topographic profile. We have to define just two elements: the input layer representing the features and a field storing the id/code/category for each feature, to be used when labelling them in the profile (Fig. 11).

Fig. 11. Line intersections UI.

In Fig. 12 the faults are represented in the plot as labelled triangles, plus the previously described seismic hypocenters (projected as points). It is therefore possible to reason on the relationships between active seisms and the mapped fault traces.

Fig. 12. Example of labelled fault intersections, together with seismic hypocenters of the 2007 Colfiorito sequence (Central Apennines).

Last case is the intersection of polygons lying on the topographic surface with the profile plane. As is the linear intersection case, we must just define two parameters: the input polygonal layer and a code/category field whose values will be used to categorize the intersections (Fig. 13).

Fig. 13. Geological polygon intersection UI.

In the following example (Fig. 14) the features intersecting the profile plane fall into just two categories, whose symbolization is chosen by the user. Under each feature intersection its code/category is written, as an help for the visualization/analysis.

Fig. 14. Example of geological polygon intersection on 3 parallel profiles in the Timpa San Lorenzo zone (Calabria, Southern Italy).

The graphical parameters window ("Define graphical parameters" in Figs. 1 and 6) allows to fine-tune the plot graphical parameters. It is possible to define the figure width and height (expressed in inches), the vertical exxageration value (1 means scale of horizontal axis equal to scale of vertical axis), and the maximum and minimum elevations (Fig. 15). Values for the vertical exaggeration and minimum and maximum elevation in the plot are precomputed, the user may however modify them.
It is possible to save the currently defined graphical parameters ("Save graphical parameters" in Figs. 1 and 6) and to load them ("load graphical parameters") in a subsequent session. A note of caution for the polygonal intersections case: loading an obsolete parameters file could cause errors when using modified category field or input values.

Fig. 15. The window for the definition of the graphical parameters.

The user can change the color for the topographic profile by defining it via the "Topographic elevations" menu item (Fig. 16).

Fig. 16. The window for the definition of the topographic profile color.

The point and attitude projections, as well the line intersections, present almost the same interface, that allows to define marker parameters and the presence of labels (Fig. 17).

Fig. 17. The window for the definition of the point projections.

In the polygon intersections case, the user defines the colors to apply, categorized by the category field previously set (Fig. 18).

Fig. 18. The window for the definition of the polygon intersections parameters.

The profile plot is created by double-clicking the "Plot" item (Figs. 1 and 6).
Just the source profile and the DEM definitions are required between plotting the profiles.
Default plot and graphical parameters will be used unless you define them using the graphical parameters definition ("Define graphical parameters" in Figs. 1 and 6).
When you modify the graphical parameters or you add geological information by using the items under "Choose geodata to plot", the plot will show the updated settings and data when the "Plot" item is double-clicked again .

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Doc version 2025-12-26, by Mauro Alberti - alberti.m65@gmail.com