val3dity---pronounced 'val-three-dity'---allows us to validate 3D primitives according to the international standard ISO19107. Think of it as PostGIS ST_IsValid, but for 3D primitives (PostGIS only validates 2D primitives).

In short, it verifies whether a 3D primitive respects the definition as given in ISO19107 and GML/CityGML. All the 3D primitives of GML are supported:

• <gml:MultiSurface>
• <gml:CompositeSurface>
• <gml:Solid>
• <gml:MultiSolid>
• <gml:CompositeSolid>

Unlike many other validation tools in 3D GIS, inner rings in polygons/surfaces are supported and so are cavities in solids (also called voids or inner shells). However, as is the case for CityGML, only planar and linear primitives are allowed: no curves or spheres or other parametrically-modelled primitives are supported. There is no plan to support these geometries, because val3dity is developed with 3D city models in focus.

val3dity accepts as input:

• CityGML
• CityJSON
• GML files of any flavour
• OBJ
• OFF

We provide the source code that you need to compile with CMake. This is straightforward under Mac and Linux.

For Windows, we offer an executable, although it's also possible to compile val3dity yourself.

To compile val3dity yourself, you first need to install the following free libraries:

1. CGAL
2. GEOS
3. CMake

Under Mac we suggest using Homebrew:

$ brew install cmake 
$ brew install cgal
$ brew install geos

Afterwards navigate to the folder with val3dity and run:

$ mkdir build
$ cd build
$ cmake ..
$ make
$ ./val3dity ../data/cityjson/cube.json

The summary of the validation is reported, and you should see that cube.json contains one valid primitive.

To see all the options:

$ ./val3dity --help

If you don't want to go through the troubles of compiling and/or installing val3dity, we suggest you use the web application. Simply upload your file to our server and get a validation report back. We delete the file as soon as it has been validated. However, a file is limited to 50MB.

Read the full documentation at http://geovalidation.bk.tudelft.nl/val3dity/docs/.

The primary channel to communicate with the developers is the Issues section.

If you have a question or came across a bug, please submit an issue there. However we ask you check first whether your problem has already been solved by someone else.