Problems with CityJson file converted from citygml

[nimafo]

I am trying to convert citygml files generated with Random3Dcity. It is a tool developed for procedurally generating 3D city models. It generates also models for interiors in 4 LoDs (0, 1, 2-2, 2-3). the problem is that after conversion to CityJson:

1. the geometry in InteriorLoD2-2 and InteriorLoD2-3 is not maintained.
2. InteriorLoD0 and InteriorLoD1 contain geometry, according to val3dity, whileInteriorLoD1 is valid, InteriorLoD1 has the following problems:

• 104: Ring_self_intersection
• 303: Non_Manifold_case
• 307: Polygon_wrong_orientation

when I redo the conversion with --vertex-precision=20, val3dity gives:

102- CONSECUTIVE_POINTS_SAME

both for InteriorLoD0 and 1. I did it again with --vertex-precision=10 and --vertex-precision=15, which resulted in the same error for LoD1 I mentioned above(104, 303, 307).

3. For InteriorLoD2-2 and InteriorLoD2-3 no geometries are maintained after conversion (error 609).
4. For LoD3, not only there is missing geometry for some building installations, but also errors 102: Consecutive points same and 201: Intersection rings.

Validation of gmls When validating geometries in 3DCityDB, for all of the 5 files I get the following errors:

• Invalid content

The complete description here. and

• '7a7cae4a-d090-4c0c-922f-a29aea3e5c26' is not a valid value for 'NCName'

Other

• When converting with citygml-tools, I get the following warning:

  The input file uses unsupported non-CityGML namespace(s): http://www.safe.com/xml/xmltables.

• This is the line of code I use for the conversion:
• .\citygml-tools to-cityjson --vertex-precision=20 "path\to\gmls"\*.gml. as mentioned above, I also did test --vertex-precision=3 which I think is the default value, --vertex-precision=10, and --vertex-precision=15. Is this the related to the above error about invalid 'NCName'?
• You can download the 5 gml files and converted cityjson ones generated from this package, including the mentioned 4 LoDs for interior and one exterior LoD3.0 file here in this link.
• I am using citygml-tools, version 2.0.0-rc.1

[clausnagel]

Thanks, @nimafo, for opening an issue. We need more information though to be able to reproduce and work on the issue.

• What dataset are you trying to convert?
• What error message is thrown by citygml-tools?
• Which version of citygml-tools are you using?
• What command-line options do you use when invoking citygml-tools?

[nimafo]

Hi @clausnagel and thanks foar your quick response, sorry for incomplete issue, I completed the description.

[clausnagel]

Can you please verify your download link? I am only able to download the errors_3DcityDB.txt file but not the CityGML input datasets.

[nimafo]

@clausnagel I updated the link, I think it should work now. Sorry for this.

[clausnagel]

Thanks, the download works now. I validated your .gml files against the CityGML schemas and all of them are invalid. You can easily validate the files yourself using the validate command of citygml-tools (use version 2.0.0 rather than 2.0.0-rc.1). Some errors and findings:

interior-LOD0.gml

• The buildings have multiple <bldg:lod1MultiSurface> geometry properties where only one is allowed. No wonder that this leads to geometry errors.
• Many objects have invalid gml:id values. The allowed values for gml:id are strictly defined in the XML world (see xs:ID and xs:NCName). For instance, a gml:id must not start with a number.
• Invalid order of elements
• Note that despite its name the file does not contain LoD0 geometries but only LoD1 geometries. Also note that CityGML 2.0 only supports interior details in LoD4.

interior-LOD1.gml

• Invalid gml:id values and invalid order of elements.
• No LoD1 geometries but only LoD2 geometries.
• Many of the solids in the CityGML file have geometry errors. I used CityDoctor v3.12.1 for geometry validation rather than val3dity. So, no wonder that there are also geometry errors in the CityJSON output.

interior-LOD2_2.gml

• Invalid gml:id values and invalid order of elements.
• The <bldg:lod2Solid> properties contain gml:MultiSolid geometries which are not allowed here. Only gml:Solid or gml:CompositeSolid are allowed. That's why the geometries of the buildings cannot be parsed by citygml-tools and hence are not converted to CityJSON.

interior-LOD2_3.gml

• Same problems as identified for interior-LOD2_2.gml.

LOD3_0.gml

• Invalid gml:id values and invalid order of elements.
• I do not see missing geometries for building installations. I visualized the CityGML file with FZKViewer and the CityJSON output with the ninja web viewer but could not spot a difference. Maybe you can point me to the missing geometries using a screenshot?
• Again, CityDoctor already reports invalid geometries for the CityGML file. So, no wonder that there are also geometry errors in the CityJSON output. You might check whether a smaller value for snap_tol makes a difference when validating with val3dity.

To make a long story short: Your CityGML input files have many issues and are invalid. There is no way for citygml-tools to convert them to clean and valid CityJSON files. So, I see no immediate action for citygml-tools. It rather seems that Random3Dcity needs some fixing.

[nimafo]

@clausnagel This is great, thanks a lot for your thorough review of the files.