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Lilien Auger

Lilien Auger

Co-founder

Dev & AI Engineer

Work

Lilien co-founded TerraLab and codes on all of it: the three QGIS plugins, the AI models behind them, and the servers those models run on. He also answers the mail users send and takes the calls they book.

Background

42 Paris alumnus. He was an AI engineer at Publicis before TerraLab. His open-source work has passed 500 GitHub stars.

Elsewhere

LinkedIn
Meet the rest of the team

Posts by Lilien Auger

A 3D view of Paris blocks around the Batignolles, each building raised to its measured height and coloured from pale yellow to dark red, beside the figure 3.07 m, the median height per story measured on 243,603 buildings.
Open DataQGISGuide

How Tall Is a Story? Floor Heights Measured on Real Buildings

We measured 307,225 French buildings: a story is 3.07 m (10.1 ft) at the median, and a 5-story building stands 16.2 m (53 ft) to the gutter.

Lilien AugerLilien Auger
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The same dense block of Dandora, Nairobi, on April 2026 drone imagery, cut into four vertical strips, each carrying one dataset's building outlines: orange Microsoft rectangles, yellow Google rectangles, magenta Overture outlines and blue OpenStreetMap outlines that follow the roofs.
Open DataQGISGuide

Microsoft Building Footprints vs Google vs Overture, Tested

Microsoft matched 25% of a French town's cadastre buildings, OpenStreetMap 83%. Then Nairobi: five free sources, timed downloads, checked on drone imagery.

Lilien AugerLilien Auger
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Hillshaded relief of a forested slope and the valley floor at Bagnères-de-Luchon, France, split in two: blurred on the left from the 30 m Copernicus DEM, sharp on the right from IGN's 1 m LiDAR HD model, with roads and a river visible, under the title Free DEM in QGIS.
Open DataQGISTutorial

Free DEM Download: SRTM, Copernicus and LiDAR in QGIS

Over one Pyrenean valley, four free 30 m DEMs sat 12 to 18 m above the LiDAR ground under forest. Where to get each DEM free, and how to load it in QGIS.

Lilien AugerLilien Auger
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The same view of central Paris cut in three vertical strips: 6,041 bike crashes as red dots on a grey street map, the same crashes as a yellow to red heat map with a red cross at Châtelet, and as orange hexagons coloured by crash count, under the title Heat maps in QGIS.
QGISTutorial

How to Make a Heat Map in QGIS (and With One Prompt)

6,041 bike crashes in Paris mapped three ways in QGIS: Heatmap renderer, kernel density raster and hexagons, then one sentence to an AI agent: 2 min 34 s.

Lilien AugerLilien Auger
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Aerial photo of the old town of Nice with the Parc du Château polygon in yellow and other city parks in pale green, beside the KML text of that park's placemark: its name, its HTML description, its style and its longitude, latitude and altitude coordinates.
QGISGuide

What Is a KML File? Open, Edit and Convert KML and KMZ

KML is map data written as XML in WGS 84; a KMZ is the zipped form. How to open, edit and convert both, and why a KMZ saved in QGIS fell to 134 bytes.

Lilien AugerLilien Auger
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Sentinel-2 true colour image near Querência, Mato Grosso, Brazil: dense Amazon forest on the right, green and pale crop fields, bare pink fields and a wetland river on the left.
QGISGuide

NDVI vs EVI, SAVI, NDRE and NDWI: Formulas for QGIS

NDVI flattens out over dense canopy. EVI, SAVI, NDRE, NDWI and NDMI each fix a blind spot. Raster Calculator formulas and a measured test in Brazil.

Lilien AugerLilien Auger
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The same block of houses with swimming pools in Tournefeuille, France, in three vertical strips: sharp at 20 cm, blocky at 3 m and an unreadable mosaic of 10 m Sentinel-2 pixels.
AI SegmentationQGISGuide

Satellite Imagery Resolution Compared: 30 m to 30 cm

One French suburb at six pixel sizes. At 10 m, 0.2% of its buildings cover 16 pixels; at 50 cm, 96% do. Counts of 20,911 buildings and 2,966 pools.

Lilien AugerLilien Auger
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The same fields and industrial estate west of Rennes, France, on 29 July 2026: sharp at 10 m from Sentinel-2 on the left, blocky at 30 m from Landsat 9 on the right.
QGISGuide

Sentinel-2 vs Landsat 8 and 9: Bands, Resolution, Revisit

Sentinel-2: 10 m pixels, 5-day revisit. Landsat 8 and 9: 30 m, a thermal band, an archive to 1972. Bands side by side, and clear views counted at three farms.

Lilien AugerLilien Auger
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Map of France with communes coloured by LiDAR HD flight year, 2021 to 2026, grey where the cloud is not published.
Open DataQGISTutorial

LiDAR HD from IGN: download and open in QGIS

The classified LiDAR HD cloud covered 78.4% of France on 6 September 2026, 30,933 of 34,877 communes. Map per commune, products, clicks in QGIS.

Lilien AugerLilien Auger
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A LiDAR HD point cloud from the French national survey, coloured by class, over the Bibliothèque nationale de France.
GeoAIQGISGuide

Photogrammetry vs LiDAR: Which One for Which Job

Photogrammetry rebuilds a surface from overlapping photos. LiDAR measures it with a laser. One gives colour and a cheap flight, the other sees under the trees.

Lilien AugerLilien Auger
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A Sentinel-2 false colour image of the Ravenna floods of May 2023, vegetation in red and flood water in dark blue.
GeoAIQGISGuide

Multispectral vs Hyperspectral: Bands, Cost and Free Data

Multispectral records 4 to 13 wide bands, hyperspectral 100 to 300 narrow ones. A table of bands, free satellites, drone sensor cost and data size.

Lilien AugerLilien Auger
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An architect's site plan of Bartow Station, drawn to scale with the building, the tracks and the property lines.
AI EditQGISGuide

Plot Plan vs Site Plan: What 19 Permit Offices Ask For

A plot plan draws one lot, a site plan the whole project. We read 19 US permit checklists: the name on the form says little about what the drawing holds.

Lilien AugerLilien Auger
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Drone photograph looking straight down on the church and village centre of Ebing, Bavaria.
GeoAIQGISGuide

What Is an Orthomosaic? Orthophoto vs Orthomosaic Map Explained

An orthomosaic is one map-accurate image stitched from many drone or aerial photos. How it is made, how it differs from an orthophoto, and how to use it.

Lilien AugerLilien Auger
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Building footprints of Shivajinagar, Bengaluru, each building its own polygon on a dense grid of streets.
AI SegmentationGeoAIGuide

Semantic vs Instance vs Panoptic Segmentation: The Difference

Semantic segmentation labels every pixel with a class: building or not. Instance segmentation draws every building as its own object.

Lilien AugerLilien Auger
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The Gas Works Park site in Seattle in 1973, a former gasworks on the lake shore before it became a park.
AI EditQGISGuide

Greenfield vs Brownfield Sites: Meaning and Differences

A greenfield site has never been built on. A brownfield site has, and may still hold slabs, sheds or contamination. What each costs and how to tell them apart.

Lilien AugerLilien Auger
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The QGIS interface with a choropleth map of median income in Houston, the layer panel on the left.
AI SegmentationQGISTutorial

How to Add a Basemap in QGIS: XYZ, WMS, QuickMapServices

Browser panel > XYZ Tiles > double-click OpenStreetMap. Then satellite tiles by URL, QuickMapServices, a national WMS, and the ground size of each zoom.

Lilien AugerLilien Auger
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Coloured LiDAR hillshade of drumlins near Hood Canal, Washington, the bare ground with the forest removed.
GeoAIQGISGuide

DSM vs DTM vs DEM: Digital Surface, Terrain, Elevation Models

A digital surface model (DSM) is the top of everything: roofs, trees, ground. A digital terrain or elevation model (DTM, DEM) is bare ground. Which to use.

Lilien AugerLilien Auger
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A glossy colored site plan of Broadway Gardens, Letchworth: warm grey buildings with drop shadows, charcoal roads, green lawns and round tree canopies.
AI EditQGISTutorial

Colored site plan: the same block four ways

Flat, watercolor, pencil and glossy, all rendered from one aerial image of Letchworth Garden City. Every prompt in full, and where the model invented water.

Lilien AugerLilien Auger
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A flat architectural site plan of Broadway Gardens, Letchworth, generated from satellite imagery: white building footprints, grey roads, green lawns and tree canopies.
AI EditQGISTutorial

Turn a Satellite Image into a Site Plan in QGIS

Load imagery in QGIS, draw a zone, and get a georeferenced four-class site plan back in under a minute. The manual route, the AI route, and where each breaks.

Lilien AugerLilien Auger
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An aerial view of Besançon with the Doubs in flood, brown water covering the quays and the riverside park.
QGISGeoAIAI Edit

How to Simulate a Flood in QGIS: 5 Methods

From the official hazard map to a generated aerial view of the water. Which method gives a number, which gives a picture, why an elevation model changes both.

Lilien AugerLilien Auger
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Aerial view of apartment blocks generated on former car parks, with the title Google Earth AI alternative.
QGISGeoAIAI Edit

Google Earth AI Alternative for QGIS

Google pulled image generation from Google Earth after one day. AI Edit runs the same Nano Banana model inside QGIS and returns a map layer, not a screenshot.

Lilien AugerLilien Auger
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An aerial view of a commercial strip road rebuilt with cycle tracks, street trees and planted forecourts.
QGISGeoAIAI Edit

How to Redesign a Street in QGIS: 5 Methods

Five ways to show a street rebuilt, from hand-drawn vector layers to a generated aerial view. Only one gives back a picture that stays on the map.

Lilien AugerLilien Auger
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AI Segmentation in QGIS: aerial imagery on the left, AI-detected building polygons on the right.
AI SegmentationQGISTutorial

AI Segmentation for QGIS: The Complete Guide

Draw a zone, name the object, get every polygon as a clean vector layer. The full run in QGIS, the three-step review in any order, and Semi-Auto mode.

Lilien AugerLilien Auger
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