# 3D Geometry-Based Indoor Network Extraction for Navigation Applications Using SFCGAL

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Methodology

## 3. Results

#### 3.1. Navigation Network from 3D Cadastral Data

#### 3.2. Navigation Network from IFC Data

## 4. Discussion

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## Appendix A

#### Appendix A.1. SQL Query for Selection of Identifiers of Geometries that Intersect in 3D Space—Method 1

#### Appendix A.2. SQL Query for Selection of Identifiers and Intersection Geometry of Geometries that Intersect in 3D Space—Method 2

#### Appendix A.3. SQL Query that Generates an Approximate Medial Axis for Each Space

#### Appendix A.4. SQL Query that Generates Points from the Approximate Medial Axis for Each Space

#### Appendix A.5. SQL Query that Finds Closest Points on Edges of the Connected Networks

#### Appendix A.6. SQL Query for Selection of Intersecting Doors and Spaces

#### Appendix A.7. SQL Query for Selection of Intersecting Doors, Spaces and Stairs

#### Appendix A.8. SQL Queries for Selection of Intersecting Doors, Spaces and Stairs with Added Intersection Geometry for the Door–Space Intersections

#### Appendix A.9. SQL Query for Selection of Spaces which do not Contain the Corresponding Centroid

#### Appendix A.10. SQL Query that Selects the Intersecting Points of Lines and Spaces for Centroid Placement in 3D

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**Figure 4.**Node-relation structure and entrance (NRSE) navigation network with red nodes and green connections.

**Figure 5.**Basic NRSE derivation method (

**a**) and the modified method for spaces with multiple connections (

**b**).

**Figure 8.**IFC test dataset [36] visualized using the FZK Viewer.

**Figure 13.**Errors in IfcSpace and IfcDoor (having equal colour) relations retrieved from the IfcRelSpaceBoundary entity.

Dataset | No. of Spaces | Method 1 | Query Appendix A.1 | Method 2 | Query Appendix A.2 |
---|---|---|---|---|---|

1 storey | 31 | 29 s | 0.08 s | 1 min 10 s | 42 s |

3 storeys | 93 | 59 s | 1.4 s | 3 min 8 s | 2 min 25 s |

6 storeys | 186 | 1 min 46 s | 7.1 s | 6 min 39 s | 4 min 28 s |

9 storeys | 279 | 2 min 58 s | 16.2 s | 10 min 16 s | 6 min 30 s |

Dataset | No. of Spaces | Method 3 | Query Appendix A.2 | Query Appendix A.3 | Query Appendix A.4 | Query Appendix A.5 |
---|---|---|---|---|---|---|

1 storey | 31 | 1 min 11 s | 42 s | 0.02 s | 0.02 s | 0.04 s |

3 storeys | 93 | 3 min 13 s | 2 min 25 s | 0.04 s | 0.06 s | 0.1 s |

6 storeys | 186 | 6 min 40 s | 4 min 28 s | 0.08 s | 0.1 s | 0.2 s |

9 storeys | 279 | 10 min 20 s | 6 min 30 s | 0.1 s | 0.2 s | 0.3 s |

Method | No. of Edges | Query | Query Time | Processing Time |
---|---|---|---|---|

Method 1 | 109 | Appendix A.6 | 0.2 s | 9.6 s |

Method 1 | 113 | Appendix A.7 | 0.2 s | 10 s |

Method 1 | 110 | Appendix A.8 | 56.6 s | 1 min 5 s |

Method 3 | 157 | Appendix A.8+ Appendix A.3 + Appendix A.4 + Appendix A.5 | 56.8 s | 1 min 9 s |

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## Share and Cite

**MDPI and ACS Style**

Tekavec, J.; Lisec, A. 3D Geometry-Based Indoor Network Extraction for Navigation Applications Using SFCGAL. *ISPRS Int. J. Geo-Inf.* **2020**, *9*, 417.
https://doi.org/10.3390/ijgi9070417

**AMA Style**

Tekavec J, Lisec A. 3D Geometry-Based Indoor Network Extraction for Navigation Applications Using SFCGAL. *ISPRS International Journal of Geo-Information*. 2020; 9(7):417.
https://doi.org/10.3390/ijgi9070417

**Chicago/Turabian Style**

Tekavec, Jernej, and Anka Lisec. 2020. "3D Geometry-Based Indoor Network Extraction for Navigation Applications Using SFCGAL" *ISPRS International Journal of Geo-Information* 9, no. 7: 417.
https://doi.org/10.3390/ijgi9070417