Data sources
Every report is traceable to these public registers.
Schaduwplan does not calculate a single figure that a third party cannot also verify. All input comes from public Dutch registers — below you will find which ones, what they do, and where you can consult them directly.
For use as evidence this matters: if a municipality (gemeente) or judge questions a value in our report, they can trace that value back to the source, down to the building identification.
Per source
What each layer contributes to your report
In the order we use them when assembling the scene.
BAGBasisregistratie Adressen en Gebouwen (Key Register of Addresses and Buildings)
Address + building + construction year · Kadaster · via PDOK
The official register of every registered building and every address in the Netherlands. For each building it provides the construction year, the usable floor area (GBO, NEN 2580) and the status (in use / demolished / under construction). Without BAG, Schaduwplan does not know where your house stands.
License: Open data (CC0). Attribution not required, but customary.
3DBAG
3D building geometry · TU Delft + 3DGI
An open 3D model of every BAG building in the Netherlands, generated from AHN laser scans. For each building it provides heights (eave, ridge, roof-height percentiles), roof type and a 3D shape we use to assemble the scene in the viewer and calculate the shadow.
License: Open data (CC BY 4.0). Requires attribution: "3DBAG by tudelft3d + 3DGI". Appears in the footer of every report.
AHN4Actueel Hoogtebestand Nederland (Current Elevation File of the Netherlands), fourth survey
Terrain and roof height (LiDAR) · Rijkswaterstaat + water authorities · via PDOK
A nationwide laser scan from an aircraft, recorded in 2020–2022 with a precision of a few centimetres. 3DBAG and the Kadaster height data are both derived from AHN4. Schaduwplan uses both the derived datasets and the raw raster: when 3DBAG is outdated for a specific building, we request the height directly from AHN4 via PDOK's WCS service.
License: Open data (CC BY 4.0). Maintained by the water authorities and Rijkswaterstaat.
AHN5Actueel Hoogtebestand Nederland (Current Elevation File of the Netherlands), fifth survey
Terrain and roof height — more recent than AHN4 · Rijkswaterstaat + water authorities · via Ellipsis Drive
The fifth AHN survey, carried out on a rolling basis per province since 2023 (see "where are we flying now"). The height algorithm has changed compared with AHN4: each raster cell now takes the highest point instead of the weighted average — better for roof edges and ridges. Schaduwplan requests AHN5 when 3DBAG's snapshot is older than the most recent AHN flight for the area (for example, roof additions built after 2022).
License: Open data (CC BY 4.0). Officially distributed via Ellipsis Drive — the hosting partner contracted by AHN for AHN5+.
AHN6Actueel Hoogtebestand Nederland (Current Elevation File of the Netherlands), sixth survey
Newest survey state — kilometre tiles · Rijkswaterstaat + water authorities · via Ellipsis Drive
The sixth AHN survey, in rotation since 2025. It delivers kilometre-tile resolution (1×1 km) instead of the older AHN map sheets (5×6.25 km), so the seams between flight strips sit closer together. For areas re-flown in 2025 or later, Schaduwplan uses AHN6 as its source — sometimes two to three years of construction activity newer than AHN5 or AHN4.
License: Open data (CC BY 4.0). Also distributed via Ellipsis Drive.
Cadastral Map (Kadastrale Kaart)
Parcel boundaries · Kadaster · via PDOK
The official parcel boundaries of every plot of land in the Netherlands. Schaduwplan shows your private parcel as a blue line on the map and records in the report whose plot is being shaded. With housing-corporation or owners' association (VvE) property, private homes are often part of a larger shared parcel — we show that as a separate layer.
License: Open data (CC BY 4.0). Attribution: "Kadaster, Kadastrale Kaart".
PDOK Locatieserver
Address search + coordinates · Kadaster
The national address search engine. When you type an address, Schaduwplan requests the BAG match here, including the exact coordinates (WGS84 for the map, RD — Rijksdriehoek — for calculation). PDOK stands for "Publieke Dienstverlening Op de Kaart" (Public Services on the Map).
License: Open data (CC0). Free to use via the OGC standard.
BGTBasisregistratie Grootschalige Topografie (Key Register of Large-Scale Topography)
Streets + water · Ministry of the Interior (BZK) · via PDOK
A detailed topographic map: roadways, footpaths, watercourses, public-space labels. Schaduwplan uses this layer solely for orientation in the viewer — it does not affect the shadow calculation or the PDF outcome.
License: Open data (CC0).
TNO standardTNO sunlight guideline — light and strict standard
Sunlight standard reference · TNO
The most widely used guideline for sunlight studies — explicitly not a law. The light TNO standard requires at least 2 hours of direct sun on fixed dates (19 February and 21 October) in the middle of the windowsill. A national statutory sunlight norm does not exist: under the Omgevingswet (Environment Act) each municipality (gemeente) chooses its own framework, and the Council of State calls the TNO standard "not unusual". Schaduwplan tests against the TNO standard plus the Hague, Rotterdam or Eindhoven variant where it applies. Note: sunlight (sun hours) is separate from daylight — the daylight requirement in the Besluit bouwwerken leefomgeving (Buildings Living Environment Decree) is statutory, but it measures the light entering the room.
License: Publicly available (guideline, not a statutory norm).
If a source is missing
You can always pin a height yourself.
When none of the AHN surveys (AHN4 from 2020–2022, AHN5 from 2023, AHN6 from 2025) has a current measurement for a specific building — think of a just-built extension, a 2024 roof addition that has not yet been re-flown, or a demolition site at the time of the survey — Schaduwplan shows an estimated height from the BAG. That estimate has an accuracy of about ±30% — not enough for a report you want to use as evidence without verifying it first.
In that case you can click Adjust in the Source data panel and enter the height yourself, based on a construction drawing or environmental permit (omgevingsvergunning). The report then states explicitly "Adjusted based on: [your source]", so traceability is preserved.
Useful public sources: Omgevingsloket · AHN viewer · BAGviewer · a construction drawing from the municipality (gemeente).
What we do not do
What is not yet in the model.
- Weather and cloud cover — the calculation assumes a cloudless sky. Typical Dutch weather with regular cloud cover is not included, in line with how judges and municipalities normally assess this too.
- Vegetation and trees — by default the scene shows no trees or greenery, because under Dutch case law trees count as "temporary landscape elements" and do not factor into the formal TNO test. You can place them optionally: their shadow is then calculated separately — useful in a neighbour-law dispute (unlawful nuisance), where a judge can take it into account.
- Indoor sunlight — the model calculates on façades and measurement points outdoors, not on light coming through windows. Furniture, curtains and room layout change indoor sunlight; that is a different type of study.
- Very recent changes — AHN5 and AHN6 are carried out on a rolling basis per province and do not yet cover the whole of the Netherlands. For areas that will only be re-flown in 2026 or later, Schaduwplan falls back on the older AHN4 survey (2020–2022) or on the BAG estimate. New buildings appear in the BAG as soon as a permit is issued, but until the next AHN flight the height is an estimate — which you can override manually in the Source data panel.
A question or complaint about a source?
If you come across an error in a source that turns up in your report — for example a wrong construction year or roof height — it should first be reported to the body that maintains that register. Let us know what you find, and we will help point you in the right direction.
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