Frequently asked questions

Pan across the map and zoom in on the area you're interested in, then click “View in 3D”: the relief drapes over the view and tilts. You then explore freely — drag to move, scroll to zoom, right-click (or two fingers) to rotate. The “Back to 2D map” button flattens the view again.

Once in 3D, two sliders appear. Vertical exaggeration amplifies elevation differences — useful for revealing gentle relief; at 1×, heights are at true scale. Tilt sets the camera angle. You can also rotate the view by dragging with the right button (or two fingers).

Two possible causes. Either the area really is flat (a plain, a body of water), or it isn't covered by LiDAR: coverage doesn't extend across all of Québec (see below). Try a hilly region: the Laurentians, Charlevoix, the Eastern Townships, or a valley floor all show marked relief.

In surface mode (the second 3D button), buildings and forest rise from the relief. But Québec 3D drapes a continuous elevation surface: it doesn't extrude building volumes. The 3D mesh interpolates between measured points, so a vertical wall becomes a ramp, never a crisp edge. On top of that, the base tiles are at zoom 16 (about 1.7 m per pixel), one notch below the LiDAR's native 1 m, which softens outlines further. The result is an “organic” relief that shows ground, canopy and built form as a single surface — the way the laser captures them — rather than CAD-style boxes.

In the map panel, click “Elevation profile”, then click on the map to set the start and each bend of the line (on a phone, tap the map). Finish with a double-click or the “Finish” button. The ground elevation curve appears at the bottom of the screen; hover over it to read distance, elevation and slope at each point. Tick “Surface” to add the ground + forest + buildings curve, and the CSV button downloads the profile. Step-by-step guide in our elevation profile article.

Gain / loss adds up the climbs and descents along the line, ignoring changes under 1 metre so that micro-undulations don't inflate the total. Slope is given as a percentage, measured over 5-metre windows (100% = 45°). The maximum height above ground, shown when “Surface” is ticked, is the tallest forest or building above the ground along the line. The line is sampled at up to 800 points, read at the level of detail that matches their spacing — one point every 1.5 to 2 metres for a short line.

Click “Line of sight” in the map panel, enter the height above ground of A and B (mast, antenna, observer), then place both points on the map. The tool checks whether the line A→B clears the terrain and, by default, the forest and buildings (the “surface”), accounting for Earth curvature and atmospheric refraction (k = 4/3). The verdict is colour-coded — clear, Fresnel zone obstructed, or blocked — with the minimum clearance and the first obstacle marked on the map. Full explanation in our line-of-sight article.

A radio wave occupies a cigar-shaped volume around the line joining transmitter and receiver: the first Fresnel zone. Its radius depends on the frequency and the link length — at the midpoint of a 10 km link, about 33 m at 700 MHz and 15 m at 3.5 GHz. An obstacle that enters it weakens the signal even when the view stays direct. A link is considered sound when at least 60% of the radius is clear: the obstacle loss then becomes negligible. Enter a frequency in MHz in the “Line of sight” tool to display this zone and its clear percentage.

Click “Viewshed” in the map panel, set the height of the observation point (30 m for a tower, for instance), the target height (1.5 m for a hand-held phone) and the radius, up to 20 km, then click on the map. All the land in view lights up around the point, with terrain, forest, buildings and Earth curvature taken into account. Click elsewhere to compare another site. The summary gives the visible share and area in km², and a curve shows the visible share by distance. Details in our viewshed article.

Green: a target at the chosen height is in direct view. Amber (“canopy reached”): at ground level the target is hidden by what immediately surrounds it — trees, buildings — but the top of that cover is in view; for a radio wave, the signal reaches it and passes through the cover, weakened. Shaded: terrain or a more distant obstacle hides both the target and its cover. In towns and forests, the green share at 1.5 m is often small: that is the real geometry, which networks offset through diffraction — the tool does not model it.

Yes: navigation is touch-based, and the 3D view uses the phone's graphics acceleration. On an older device, if the relief view stutters, zoom out a little or lower the vertical exaggeration.

From LiDAR surveys of Québec, produced and released as open data by the Ministry of Natural Resources and Forests (MRNF). We retrieve them from Données Québec and turn them into navigable relief. To understand how an airborne laser produces this data, read our introductory article.

The digital terrain models are delivered at 1-metre resolution (one elevation per one-metre cell), with vertical accuracy on the order of a few centimetres. We render this data without recomputing it: the relief you see is the MRNF's.

No. LiDAR coverage focuses on inhabited and developed areas, and expands with each acquisition campaign. Some remote regions haven't been surveyed yet; they appear without detailed relief.

The default map is an analytical hillshade of the relief: simulated oblique lighting that brings out bumps and hollows. No third-party basemap is used — you're looking only at the LiDAR terrain.

The near-infrared LiDAR laser is absorbed by water and doesn't measure its surface reliably. Each body of water therefore carries the elevation captured at the moment of the flight, which varies with tide and campaign: in 3D this can produce plateaus or slight steps on watercourses. This is a limitation of the source data, not a display error. The ground relief itself remains faithful.

Not from this site: Québec 3D is a visualization, not a repository — only the elevation profile of a line can be exported as CSV. The original files (point clouds and terrain models) are available free of charge on Données Québec.

Québec 3D is a tool for exploration and understanding, not an engineering document or an official map. For professional use, rely on the original Données Québec data and on the appropriate certified surveys. See our Terms of Service.

The site is free, with no account, no advertising and no collection of personal data. It is served as a static site: nothing you explore is sent to a server.

Email us at contact@quebec3d.org. The Contact page lists the details worth including in a report (area concerned, browser, screenshot).