AI Agent (by TerraLab) in QGIS to fetch security installations

Mapping Abuja’s Security Infrastructure: How to Fetch Point Layers using TerraLab's AI Agent for QGIS

Geospatial data extraction has historically required jumping between specialized data web portals, building complex Overpass API queries, or manually digitizing locations. However, with the emergence of AI agents built directly into GIS environments, extracting specific spatial data is now as simple as writing a chat message.

In this guide, we will walk through using the AI Agent by TerraLab inside QGIS to automatically pull a comprehensive point layer of security installations within the Abuja Municipal Area Council (AMAC), Nigeria. We will cover police stations, military cantonments/barracks, and the Nigeria Security and Civil Defence Corps (NSCDC) offices.

I decided to try the AI Agent in QGIS, I installed the AI agent by TerraLab via the plugin manager, it was a great expereice to say the least. It literally completed a task for me in way less minutes than I would have done it manually. Here are the details of what I tasked it to do;-

Task/Prompt: I need point layer for all the security agents offices in Abuja Municipal Area Council (AMAC) including Police stations, Millitary cantonments/baracks and Nigeria Security & Civil Defence Corps.

Result: As seen below, it successfully retrieved 53 points for the result. Although, not all were security infrastructures I expected, so I did some manual verification and cleaning.

How to Install and Initialize the AI Agent

Before prompting the agent, ensure you have the plugin installed and ready in your workspace.

1. In QGIS, navigate to the top menu and select Plugins > Manage and Install Plugins.
2. Search for AI Agent by TerraLab and click Install Plugin.
3. Once installed, open the agent interface panel using the keyboard shortcut Ctrl + Alt + A (or click the TerraLab icon in your toolbar).
4. Sign in to your account to activate your monthly free message allowance.

After you are signed in, enter the prompt and once you hit submit, the AI Agent creates an execution plan which you can monitor live in the side panel:

1. Boundary Retrieval: The agent queries global administrative databases to find the official polygon layer for AMAC.
2. Data Extraction: It simultaneously queries regional open datasets using tags like amenity=police, military=barracks, and generic security/government office infrastructure filters tailored to Nigeria's public safety sectors.
3. Reprojection & Layer Creation:

The data is transformed into your project’s Coordinate Reference System (CRS) and compiled into a dedicated point feature layer.

4. Symbology Application: Instead of generic circles, the agent can apply categorized styling, assigning separate colors or icons for Police, Military, and NSCDC sites if that was stated in the initial prompt.

One of the most powerful aspects of the TerraLab AI Agent is its built-in safety net. If the agent misinterprets a layout or grabs points outside your target area, you don't have to manually delete elements. You can use the one-click Undo checkpoint feature in the panel to revert the changes and refine your prompt.

Once you are satisfied with the layer, you can right-click the newly generated layer in your QGIS Layers Panel and select Export > Save Features As... to save the clean dataset permanently as a GeoPackage or Shapefile for your local security intelligence audits.

By leveraging the AI Agent by TerraLab, what used to be a tedious multi-step data mining workflow is reduced to a single conversational task. Whether you are mapping critical infrastructure for urban planning or conducting risk assessments in Nigeria's capital, AI-driven GIS tools ensure your time is spent analyzing data rather than hunting for it.

Happy AIing!

How to create stacked axonometric/isometric map in Inkscape

 To create a stacked axonometric map in Inkscape, you can build the diagram using flat 2D layers and then apply Inkscape’s axonometric grid and transform tools to slant the layers into a uniform 3D perspective.

Sample figure: Axonometric/Isometric Map of Nigeria States + LGA + Wards

Note that the core base maps in the example above were prepared in a GIS software before being imported into inkscape for the layer stacking and transformation into axonometric/isometric map.

Here is the step-by-step workflow to create and stack your map layers perfectly:

Step 1: Set Up an Axonometric Grid

1. Go to File > Document Properties (or press Ctrl + Shift + D).
2. Select the Grids tab.
3. In the dropdown, change Rectangular grid to Axonometric grid and click New.
4. Adjust the Grid units (e.g., px or mm) and set your preferred angles. The default X-angle and Z-angle are usually set to 30.0 degrees, which works perfectly for standard isometric/axonometric drawings.

Step 2: Organize Your Map Layers

Using separate layers will keep your workflow clean and make it easy to move the maps vertically.

1. Open the Layers panel by going to Layer > Layers and Objects (Ctrl + Shift + L).
2. Create a separate layer for each map level you plan to stack (e.g., Layer 1: States, Layer 2: LGAs, Layer 3: Wards etc).

Step 3: Draw or Import Your Flat Assets

It is much easier to design your map elements flat before turning them into 3D.

1. Select your first layer and draw your map elements (roads, site boundaries, shapes) or import an existing 2D vector file.
2. Group the elements of that specific map level together by selecting them and pressing Ctrl + G. Repeat this for every layer.

Step 4: Transform to Axonometric View

If you didn't draw your layers directly on the 3D grid, you can transform flat elements using the Transform Panel:

1. Open the panel via Object > Transform (Ctrl + Shift + M) and click the Rotate tab.
2. Select your flat 2D group and rotate it by 45°. Click Apply.
3. Switch over to the Skew tab in the same panel.
4. Set the Skew X to -26.565° (or 26.565° depending on your preferred orientation) and leave Skew Y at 0. Click Apply.
5. Your flat vector map will now perfectly match a standard 30-degree isometric/axonometric grid line. Repeat this exact sequence for every group on your other layers.

Step 5: Stack and Align Your Layers

1. Turn on Snapping from the top-right corner toolbar. Make sure Snap to grid lines and Snap to nodes/intersections are turned on.
2. Select a layer group and hold Ctrl while dragging it vertically. Holding Ctrl restricts movement to a perfectly straight vertical line.
3. Space out your layers evenly. You can map out a specific distance by counting the grid intersections or using the Align and Distribute panel (Ctrl + Shift + A).

Step 6: Draw Connecting Dash Lines

To show how the layers structurally relate to each other, add vertical guidelines:

1. Select the Bezier Tool (or press B).
2. Click a key anchor point on your bottom map layer (like a site corner or a major intersection point) and draw a straight vertical line upward to the exact same point on the top map layer.
3. Open Object > Fill and Stroke (Ctrl + Shift + F). Go to the Stroke style tab and change the Dashes dropdown to a clean dashed pattern. Lower the opacity or change the color to a light gray so it functions as a subtle guide.

Map of Nigeria Senatorial Districts, Federal Constituencies and State Constituencies

Stacked Map of Nigeria Senatorial Districts on different shades of colors

You can use "SSR technique" (Scale-Shear/Skew-Rotate), to transform any object into top plan, left wall or right wall views. I wrote about SSR technique here.

Transform Menu Settings for Isometric Transformations

That is it!

Axonometric Drawing - SSR (Scale, Shear/Skew, Rotate) technique

 The SSR (Scale, Shear, Rotate) technique is a highly efficient mathematical workflow used in vector graphic programs like Adobe Illustrator and Inkscape to precisely transform flat 2D orthographic drawings into a 3D isometric axonometric projection. Instead of tracing flat blueprints onto an isometric grid by hand, the SSR method automates the deformation using exact numerical inputs.

The technique relies on mathematically shifting the 2D plane so that a standard square conforms perfectly to the true 30-degree / 120-degree orientation of an isometric drawing.

The Three Pillars of SSR

To project a flat 2D face onto one of the three visible planes of a 3D cube (Top, Left, or Right), you apply three sequential operations to your vector object:

1.  Scale: This accounts for the foreshortening effect of looking at an object from an isometric angle. You scale the vertical height of the object down to 86.602% while leaving the width at 100%.
2.  Shear (or Skew): This slants the vertical edges of the object to mimic a parallel projection angle, tilting them by 30° or -30°.
3.  Rotate: This turns the entire asset into the final orientation required for that specific plane, shifting it by 30° or -30°.

The Standard Transformation Values

Depending on which side of the axonometric drawing you are generating, apply these specific transformations in order:

Isometric Plane	1. Scale (Vertical)	2. Shear (Skew)	3. Rotate
Top Plane 🪵	86.602%	30°	-30°
Left Plane 🧱	86.602%	-30°	-30°
Right Plane 🧱	86.602%	30°	30°

(Note: Some software packages require a 30° Shear and a 30° Rotation for the Left Plane, or flipped symbols depending on how the software measures clockwise vs. counter-clockwise angles).

The 86.602% vertical scale factor in the SSR technique is not an arbitrary number—it is the exact trigonometric value of 

It acts as a mathematical pre-compensation filter. When you skew (shear) an object in a vector program by 30°, the software stretches the geometry. Scaling the vertical axis down to 86.602% beforehand ensures that after it stretches, the final lines return to exactly 100% of their original true length, maintaining a perfect 1:1:1 aspect ratio across all 3D axes.

Here is the exact geometric breakdown of why this happens.

1. The Trigonometry of the Shear Step

When you apply a 30° Shear to a flat square, the horizontal lines of your drawing tilt upward by 30°.

In vector graphics, a shear shifts points along one axis proportional to their distance from the other axis. This distorts the right angles of your flat square into an isometric diamond (rhombus). During this distortion:

• The width (horizontal boundary) of the bounding box remains fixed.
• The horizontal lines tilt up at a 30° angle, turning into the hypotenuse of a right-angled triangle.

According to right-triangle trigonometry:

Rearranging this formula to find the new length:

This means that shearing a flat object by 30° automatically stretches its line segments by roughly 115.47%.

2. Eliminating the Distortion (Why we Scale First)

If you don't scale the graphic before shearing it, your final 3D object will look elongated and structurally warped because the lines on the isometric plane are longer than they should be.

To counteract this 115.47% expansion, you must shrink the asset by the exact reciprocal amount before the shear takes place:

By scaling the vertical size to 86.602%, you intentionally compress the object. When the 30° shear step elongates the lines by 115.47%, the two operations cancel each other out perfectly:

3. Isometric Drawing vs. Isometric Projection

There is a subtle but important distinction in technical drawing that explains why this scale factor is so highly regarded:

• True Isometric Projection: When an actual 3D cube is rotated in physical space (45° horizontally, then 35.264° downward toward the camera), all axes shrink uniformly to 81.65% of their real-world size due to perspective foreshortening.
• Isometric Drawing (The SSR Approach): Graphic designers prefer a 1:1 scale so that a 100px line on a flat blueprint remains exactly 100px long on the 3D isometric axis. The SSR technique achieves this "true measurement" standard. By scaling vertically to 86.602% before shearing, the final 3D drawing retains an un-foreshortened, easily measurable 100% scale on all visible faces.

To calculate alternative scale values for other axonometric projections, you must determine how much the shear (skew) angle stretches the artwork and use trigonometry to cancel out that distortion.

The universal formula to find the required vertical scale factor for any parallel projection using the Shear-Rotate method is:

(Where ϴ is the shear angle you intend to use).

Thank you for reading.

Creating REM from DEM in QGIS

 REMs are best produced from LiDAR data, however my region of interest has no publicly available LiDAR dataset. So, I will use high-resolution DEM from "Copernicus Global Digital Elevation Models" distributed by OpenTopography because it offers superior horizontal and vertical accuracy compared to SRTM DEM data. To cite this data, use:-

European Space Agency (2024). Copernicus Global Digital Elevation Model. Distributed by OpenTopography. https://doi.org/10.5069/G9028PQB. Accessed 2026-09-05

This study area is the Uke river (approximately Latitude 8°35'N to 9°05'N and Longitude 7°35'E to 7°55'E) that streches from Karu LGA into Nasarawa LGA all within Nasarawa state. The Uke river is a dynamic, seasonal river system that feeds into the larger Uke-Antau-Mada drainage basin, just east of Abuja.

What is Relative Elevation Model

A Relative Elevation Model (REM), also called a detrended digital elevation model or height-above-river raster, is a specialized 3D map that shows land height relative to a nearby river channel rather than above sea level.

Traditional Digital Elevation Models show absolute height above sea level. Because rivers naturally slope downward from their source to their mouth, this overall slope can hide small, local changes in the landscape.

An REM "flattens" the river's downward slope by setting the riverbed elevation to zero everywhere.

Software takes a standard elevation grid, estimates the water level along the river's center line, and subtracts that predicted river height from the original elevation data.

A value of zero means the ground is level with the nearest river channel, while positive numbers show how high a specific spot sits above that river.

Steps for Creating a Relative Elevation Model

Step A: Reproject and Clip

• Open your downloaded GeoTIFF in QGIS.
• Reproject the layer from WGS 84 (Geographic) to a projected coordinate system for accurate distance measurements. For Nasarawa State, use WGS 84 / UTM Zone 32N (EPSG:32632).

Step B: Extract River Vector and Elevation

1. Manually digitize the centerline of the Uke River as a line vector layer, or extract it automatically using the SAGA Channel Network tool.
2. Use the Extract Vertices tool to convert the Uke River line into a series of dense point features along the channel.
3. Open the Sample Raster Values tool. Use your reprojected DEM to add the exact elevation (Z-value) to every point along the river channel.

Step C: Create the Arbitrary River Plane

1. Open the Inverse Distance Weighting (IDW) Interpolation tool under the QGIS Processing Toolbox.
2. Set the input layer as your sampled river points and select the sampled elevation attribute as your vector interpolation field.
3. Set the extent to match your clipped study area and run the tool. This creates a smooth, continuous "water level baseline surface raster" that mimics the downhill slope of the river.

Step D: Calculate the Relative Elevation Model

1. Open the Raster Calculator.
2. Enter the formula: [Projected_DEM] - [IDW_Interpolation_Surface]
3. Run the calculation.

The resulting layer is your REM. All values of 0 will represent the exact channel bed of the Uke River, while higher values represent the exact height of the surrounding terrain relative to the closest point of the riverbed, perfectly highlighting paleochannels, floodplains, and terrace heights.

Thank you