PNOA LiDAR and IGN open data: a guide to download and use

The open mapping data published by the IGN (Spain’s National Geographic Institute) is the PNOA orthophoto, the PNOA LiDAR point cloud and the digital models derived from it (DTM and DSM). It is free, it is downloaded from the CNIG Download Centre and it is useful for preliminary studies, options and context; detailed design usually needs data that is more recent, denser and of verified accuracy.

This guide sets out which products exist and at what resolution, how to download them, under which licence they can be used and when your own flight is worth it. The figures come from the technical specifications and the coverage pages published by the IGN itself (consulted in October 2026). Before using any dataset, read the metadata sheet for its area.

What the PNOA is and what the IGN publishes

The PNOA (Plan Nacional de Ortofotografía Aérea, Spain’s National Aerial Orthophoto Programme) is the IGN programme, run with the regional governments, that periodically flies the whole of Spain. It was created to produce orthophotos and, since 2009, it has included flights with an airborne LiDAR sensor. Four families of open data come from those flights:

• PNOA orthophotos: corrected aerial images, in colour and, in many editions, with an infrared version.
• PNOA LiDAR: classified point clouds.
• DTMs (MDT): grids of ground heights, derived from the ground points.
• DSMs (MDS): grids that include buildings and vegetation, derived from the first returns.

All of them are distributed from the CNIG Download Centre (Centro de Descargas of the Centro Nacional de Información Geográfica), the IGN’s download platform. Its public dissemination policy, set out in Order FOM/2807/2015, allows the IGN’s products to be downloaded free of charge and reused.

PNOA orthophotos

A PNOA orthophoto is an aerial image corrected geometrically so that it can be measured. The IGN offers the most-current series, a mosaic of flights of different dates, and earlier series to see how an area used to look.

• Resolution: the most-current orthophoto is published with a 25 cm pixel over much of the territory and 50 cm in other areas. The flight date varies from one area to another.
• Reasonable use: locating a project, a preliminary study, comparing dates, an indicative check of boundaries.
• Limit: at 25 cm per pixel small features cannot be identified, and the accuracy of the national orthophoto is intended for planning scales, not for detailed design.

The difference from an aerial photo is covered in what is an orthophoto; what a flight of your own delivers is on the drone orthophoto page.

PNOA LiDAR: the point cloud

PNOA LiDAR is the IGN’s airborne laser flight. It produces a point cloud with coordinates, intensity, return number and class, in ETRS89 (or REGCAN95 in the Canary Islands), with orthometric heights referred to the EGM08 geoid. It has been flown in three coverages, each improving on the last.

How to read the table:

• «Up to» means it is the specified limit: the IGN sets that accuracy as a requirement of the flight. It is not the accuracy of the cloud at every corner of the tile, which gets worse under dense vegetation or on steep slopes.
• The specified horizontal accuracy is up to 30 cm in the first two coverages and up to 25 cm in the third.
• The second coverage varies by lot: the IGN page gives a density from 0.5 up to 4 points/m² (14 in Navarre) and a vertical accuracy of 15 to 20 cm depending on the lot. The figure for each area is on the page for its lot.
• The third coverage is still being completed: according to the IGN, it started in 2021 in Catalonia and in 2023 in the other regions, with the end planned for 2025.
• Classification improves: the first and second coverages distinguish five basic classes; the third at least thirteen, including ground, vegetation by height and buildings.
• Imagery captured during the flight, which can be used to colour the cloud, is available from 2016 in the second coverage and in the third.
• Format: the points are distributed as LAZ, the compressed version of LAS.

To put those densities in context: at 0.5 points/m² there is one point every 2 m². At 5 points/m², one every 0.2 m². A drone LiDAR flight records a much higher density, in the order of tens to hundreds of points per square metre depending on the sensor, height and flight speed. How the sensor works is explained in what is LiDAR and how it is used in mapping.

Digital terrain models: MDT02, MDT05 and MDT25

The IGN generates the DTMs from the points classified as ground in the LiDAR cloud. The process includes editing to remove artefacts, gap filling by interpolation where there is no data, and quality control. Reservoirs and the sea are set to a constant height. They are published in several grid steps:

• MDT02: 2 m grid step, where coverage allows.
• MDT05: 5 m grid step. It is the most widely used terrain model and the one with the broadest coverage.
• MDT25 and MDT200: coarser grids, for regional analysis and small-scale maps.
• 0.5 m model of the third coverage: the IGN technical specifications set a model with a 0.5 m grid step for it (vertical RMSE of up to 15 cm), against 2 m in the second coverage and 5 m in the first. The IGN page for the DTM only mentions steps of 2 or 5 m, so check in the Download Centre whether it is published for the area.

Each cell stores a single height. A 5 m grid smooths embankments, ditches, terraces and walls, because a feature narrower than the cell disappears or is averaged. MDT05 is a good starting point for slopes, catchments and district-level hydrology.

Digital surface models and the LiDAR Map

The IGN’s MDS (DSM) is the model «with obstacles»: it records the highest height in each cell, whether ground, vegetation, building or pole. It is generated from the first returns of the ground, vegetation and building classes, and is published with a 2 or 5 m grid step depending on the area.

The Mapa LiDAR is a different product: a raster visualisation of the cloud, with a 2.5 m pixel, combining a shaded surface with layers for vegetation, buildings and water. It is for looking at the shape of the ground and of what stands on it, not for measuring.

MDT (DTM) is the bare ground, MDS (DSM) the surface with whatever stands on it, and MDE (DEM, digital elevation model) is the general term covering both. The full comparison is in DTM vs DSM: differences and when to use each; what a survey of your own delivers is on the digital terrain model (DTM) and digital surface model (DSM) pages.

Comparison table of IGN products

The figures are those specified by the IGN; the actual coverage of each area and its date are checked in the Download Centre.

How to download IGN data step by step

The process is similar for every product. Menu names may change when the CNIG updates the portal, but the logic is the same.

1. Go to the CNIG Download Centre, accessible from the IGN website. Downloading is free; depending on the product it may ask for a free registration.
2. Choose the product: orthophotos, digital elevation models (DTM and DSM) or LiDAR (point clouds). If in doubt, start with the coarsest product and work down.
3. Locate the area. You can search by municipality or province, draw a polygon on the map or select sheets of the National Topographic Map.
4. Choose the coverage or edition. In areas with several flights, download the most recent one unless the aim is to compare dates. The PNOA website has a page with the status of each coverage.
5. Add the files to the basket and download them. LAZ clouds weigh tens or hundreds of megabytes per tile, and a whole district is several gigabytes. DTMs and orthophotos weigh less.
6. Keep the metadata sheet of each product: flight date, density, reference system, specified accuracy and the licence attribution. That sheet is what is cited in the project.

How to open the data

• LAZ clouds: QGIS reads them natively; so does CloudCompare, which is free, and professional LiDAR software.
• Raster DTM and DSM: QGIS, ArcGIS, Global Mapper or AutoCAD Civil 3D.
• Reference system: check that the project works in the same UTM zone as the data (29, 30 or 31 depending on the sheet; the Valencia region, Comunitat Valenciana, is split between 30 and 31) and in the same height system. The IGN uses orthometric heights with the EGM08 geoid; mixing them with ellipsoidal heights produces height shifts of tens of metres.

IGN data licence and how to cite it

The products in the Download Centre are published under the Creative Commons Attribution 4.0 licence (CC BY 4.0). It allows the data to be copied, distributed and transformed, including for commercial purposes, on one condition: credit the author, link to the licence and indicate whether changes have been made.

Every plan, report or figure that uses IGN data must carry an attribution. The wording fita uses on its own website is:

• «© Instituto Geográfico Nacional», for the digital models and the point cloud.
• «PNOA cedido por © Instituto Geográfico Nacional», for orthophotos.

A full citation in a technical report also includes the product name (for example MDT05), the download or flight date and the reference system. The metadata sheet of each product gives the exact wording the IGN asks for. If the data is processed, for example to generate contour lines, the figure should state that it is a derived work.

How to check a dataset before using it

Downloading is only the first step. Deciding whether the data is fit for purpose takes four checks on the metadata sheet:

1. Capture date. It is not the publication date: a tile may come from a flight a decade ago.
2. Actual density or resolution of the area, and classification. The first coverage has 0.5 points/m² and the third 5; with few classes, ground under vegetation is harder to tell apart.
3. Specified accuracy. The IGN figure is a requirement of the flight. It does not replace control of the specific site.
4. Reference system and heights. UTM zone, ETRS89 and type of height.

If any of them does not fit what the project requires, public data is context, not a basis for calculation.

When you need your own flight

Public data solves the outline design, the study of options or catchment hydrology. A construction design, site control or a volume calculation usually needs more. There are five main reasons.

Capture date

Several years pass between two PNOA coverages. If earth has been moved on the parcel, something has been built, trees have been felled or there has been a flood, the cloud describes terrain that no longer exists. A solar plant layout, construction progress monitoring with drones or a quarry volume calculation needs today’s terrain.

Density

With a density of only a few points per square metre (0.5 to 5 as specified values, and somewhat more in some lots), the model does not capture ditches, walls, kerbs, small embankments or the shape of a stockpile. Features smaller than a metre disappear or are smoothed out. A drone LiDAR survey records a much higher density and models those features. From the resulting model, reliable contour lines at a small interval can be produced.

Vegetation

Under trees or dense scrub, a low-density cloud has few ground points and the DTM interpolates between them: the resulting ground may be smoother than the real one. A flight of your own checks the coverage of ground points and indicates where the model is reliable.

Work in progress

A construction site changes every week. To measure progress, compare campaigns or calculate volumes, you need a capture date that the project controls and the same method on every campaign. IGN products are not designed for that.

Required accuracy

A vertical accuracy of up to 10 cm, as specified for the third coverage, is fine for planning and outline design. Earthworks, a plant’s drainage network or a road’s design levels need higher accuracy and, above all, a control that can be demonstrated.

In a drone flight supported by its own ground control points, typical accuracy is 2 to 5 cm, expressed as root mean square error (RMSE) on open ground or well-defined surfaces, in the project reference system (ETRS89 / UTM, with orthometric heights unless another reference is requested). It is checked against independent checkpoints that are not used in the adjustment. It depends on the sensor, the GSD, the ground control and the vegetation. GSD is the resolution of the image, not its accuracy. The accuracy for each project is agreed in the proposal and documented in the control report. The article how to check a topographic delivery explains what it should contain.

Other cases

• Small areas on the edge of several tiles with different dates.
• Power lines: a power line inspection with drones needs specific density and classification of conductors and vegetation.
• Tender documents that require a control report for the job itself. The LiDAR survey specification lists what to ask for.

Combining IGN data with your own flight

It is not an either-or choice. A sensible workflow is:

1. Download the MDT05 or the PNOA cloud for the whole study area for the analysis of alternatives and the context.
2. Define the final project boundary.
3. Fly LiDAR or drone photogrammetry over that boundary only, with ground control points and accuracy control.
4. Integrate the two models: your own within the project boundary, the public one in the surroundings, with the date, accuracy and attribution of each documented.

That way, the flight is concentrated where accuracy matters and the project keeps its context. For flooding, the article on flood zone maps and the role of the DTM explains the limits of each source.

Frequently asked questions

Is PNOA LiDAR data free for commercial use?

Yes. IGN and CNIG products are published under the CC BY 4.0 licence, which allows commercial use on condition that the IGN is credited as the author and the licence is linked. The metadata sheet of each product gives the attribution.

How often is the LiDAR map of Spain updated?

There is no schedule that is the same for the whole country. Coverages are flown by area in cycles of several years: the first between 2009 and 2015, the second between 2015 and 2021 and the third from 2021 in Catalonia and from 2023 elsewhere, with the end planned for 2025. The exact date of each tile is shown in the Download Centre.

What resolution does the IGN DTM have?

It is published with a 2 m grid step (MDT02, where coverage allows) and a 5 m step (MDT05), as well as coarser grids such as MDT25. For a district-scale study, MDT05 is usually enough. For design work, compare the date, resolution and accuracy of the data with what detailed design requires.

Can I generate contour lines from PNOA LiDAR?

Yes, with QGIS or any GIS from MDT02 or MDT05. With intervals of 5 or 10 m the result is reasonable. With intervals of 1 m or less you need a denser and more accurate model than public data usually offers. The article on contour lines, interval and how they are made from a DTM goes into detail.

If your project is in the Valencia region or anywhere else in Spain and the public data falls short in date, density or accuracy, our drone surveying service and the point cloud page explain what we deliver and with what quality control.

Written by the fita team, drone mapping and surveying in Xàtiva (Valencia, Spain).