GeoLibre
The GeoLibre heading groups three tools contributed by the GeoLibre engine itself, alongside the Whitebox suite that fills the rest of the toolbox. They share one subject: the nested structure of depressions and of raised features in an elevation model.
They implement the level set approach developed for LiDAR derived terrain analysis, where a depression is not a single object but a hierarchy. A large basin contains smaller hollows, which contain smaller ones again, exactly as a series of contour lines would show.
Start here
Section titled “Start here”Extract Sinks
Section titled “Extract Sinks”The starting point. It finds the depressions in your elevation model and returns their maximum extent, that is the surface each one would cover if filled to its spill level.
Where Sink, in Depressions & Storage, marks the cells belonging to a depression, this tool gives you the depressions as objects, with their full footprint. Directly useful for mapping ponds, wetlands and prairie potholes.
Delineate Depressions
Section titled “Delineate Depressions”Goes one step further and returns the nested hierarchy: which depression contains which, and at what level each one appears. Instead of one flat map of hollows, you get their structure.
This matters for wetland inventories, where a large seasonal basin behaves very differently from the small permanent pools inside it, and for storage estimation, where the level at which one hollow starts spilling into the next is the whole question.
Delineate Mounts
Section titled “Delineate Mounts”The same analysis turned upside down, applied to raised features. It returns the nested hierarchy of mounts: hills within a plateau, knolls within a hill.
Useful for landform mapping, and for detecting built structures or archaeological features in a high resolution model.
All the tools
Section titled “All the tools”| Tool | What it does |
|---|---|
| Extract Sinks | Returns the maximum extent of each depression in the elevation model. |
| Delineate Depressions | Returns the nested hierarchy of depressions, using the level set method. |
| Delineate Mounts | Returns the nested hierarchy of raised features. |
High resolution pays off. These tools were designed for LiDAR derived models, where hollows of a few tens of centimetres are real and measurable. On a coarse global model they will mostly find interpolation artefacts.
Condition afterwards, not before. Run these on your raw elevation model. Once the depressions have been filled or breached, there is nothing left for them to find.