21/4/2015 Dr. Ahmad Yousef
The Use of GIS for 3D Urban Models
Reconstruction Based on Aerial Lidar Data
Dr. Ahmad Yousef
21/4/2015 Dr. Ahmad Yousef
• Overview
• Objectives & Goals
• Digital Terrain Model Extraction
• 3D Building Model Reconstr...
21/4/2015 Dr. Ahmad Yousef
Pollution, Cairo
Visualization, Dubai
Pollution, Moscow
Flood, Pakistan
Visualization, Los Ange...
21/4/2015 Dr. Ahmad Yousef
Year : 2050
66%
Year : 2014
54%
Urban Population
World
Source: UN DESA’s Population Division
of...
21/4/2015 Dr. Ahmad Yousef
Overview
Why lidar data …
Waldkirch, Germany
21/4/2015 Dr. Ahmad Yousef
Overview
Workshop Objectives & Goals
21/4/2015 Dr. Ahmad Yousef
Overview
Workshop Objectives & Goals
21/4/2015 Dr. Ahmad Yousef
Overview
Workshop Objectives & Goals
1. Introduce a fast and simple integrated Digital Terrain ...
21/4/2015 Dr. Ahmad Yousef
Overview
Workshop Objectives & Goals
1. Introduce a fast and simple integrated Digital Terrain ...
21/4/2015 Dr. Ahmad Yousef
Digital Terrain Model Extraction
How to classify lidar data into terrain and off-terrain points?
21/4/2015 Dr. Ahmad Yousef
• Filtering means classification of points into terrain and off-terrain.
• Bare earth is assume...
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Esri Terrain Dataset
Surface geometry at different resolution (TINs)
– TIN is ac...
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Esri Terrain Dataset
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Esri Terrain Dataset
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Esri Terrain Dataset
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Esri Terrain Dataset
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Minimum Block Classification - MBC
Window Block
Bare Earth Surface
Input Points ...
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Minimum Block Classification - MBC
Input Points Dataset [Geodatabase], Input Win...
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Minimum Block Classification - MBC
Input Points Dataset [Geodatabase], Input Win...
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Digital Surface Model
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Digital Terrain Model
21/4/2015 Dr. Ahmad Yousef
Digital Surface Model Shaded Relief
DTM Extraction
Forest Dataset …
Digital Terrain Model Shade...
21/4/2015 Dr. Ahmad Yousef
45m x 35m
DTM Extraction
Urban Dataset …
5 750 000 Points
21/4/2015 Dr. Ahmad Yousef
DTM Extraction
Urban Dataset …
21/4/2015 Dr. Ahmad Yousef
3D Building Models Reconstruction
How to fulfill the gap between lidar data and building models...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Buildings Shapes …
Redlands, USA. Source : Google maps
21/4/2015 Dr. Ahmad Yousef
3D Building Model
No Comments …
Venezuela. Barrio Petare, Caracas.
Source: A sustainable approa...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Level of Details LoD
• Building model is the representation
used for describi...
21/4/2015 Dr. Ahmad Yousef
Model Structure Based – Model Derive
3D Building Model
Modeling Approaches
• Model Database.
• ...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Modeling Approaches
Source: International Summer School “Digital Recording an...
21/4/2015 Dr. Ahmad Yousef
Data Structure Based – Data Derive
3D Building Model
Modeling Approaches
• Roof described by pl...
21/4/2015 Dr. Ahmad Yousef
Input for Data Derive Model
3D Building Model
Modeling Approaches
I. Points based
– Points may ...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Building Model Elements
Planar Patches
Wall
Footprint
Planar Face
TIN Triangl...
21/4/2015 Dr. Ahmad Yousef
5 Processing Steps :-
3D Building Model
Framework …
1. Generate Triangle Irregular Network - TI...
21/4/2015 Dr. Ahmad Yousef
21/4/2015 Dr. Ahmad Yousef
3D Building Model
1 - Triangle Irregular Network
21/4/2015 Dr. Ahmad Yousef
3D Building Model
1 - Triangle Irregular Network
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
A.X + B.Y + C.Z + D = 0
N=(A,B,C)
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Normal Vector Estimation
1 Ring Neighborhood ...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Normal Vector Estimation
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Normal Vector Estimation
21/4/2015 Dr. Ahmad Yousef
1 Ring Neighborhood
3D Building Model
2 - Extract Roof Planar Patches
Normal Vector Estimation
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Normal Vector Estimation
2 Rings Neighborhood
21/4/2015 Dr. Ahmad Yousef
2 Rings Neighborhood
3D Building Model
2 - Extract Roof Planar Patches
Normal Vector Estimation
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Segmentation & Region Growing
Apply region gr...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Segmentation & Region Growing
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Segmentation & Region Growing
21/4/2015 Dr. Ahmad Yousef
3D Building Model
2 - Extract Roof Planar Patches
Segmentation & Region Growing
21/4/2015 Dr. Ahmad Yousef
3D Building Model
3 - Detection of Planar Roof Faces
21/4/2015 Dr. Ahmad Yousef
3D Building Model
3 - Detection of Planar Roof Faces
Vertical Triangles
All triangles with slop...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
3 - Detection of Planar Roof Faces
Least Square Plane Fitting
A * X + B * Y +...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
3 - Detection of Planar Roof Faces
Intersection of adjacent patches
A * X + B...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
3 - Detection of Planar Roof Faces
Merging Planar Patches
21/4/2015 Dr. Ahmad Yousef
3D Building Model
4 - Intersection of Roof Planes
Patch 1 2 3 4 5 6 7
1 YES YES YES YES
2 YES Y...
21/4/2015 Dr. Ahmad Yousef
3D Building Model
4 - Intersection of Roof Planes
21/4/2015 Dr. Ahmad Yousef
3D Building Model
4 - Intersection of Roof Planes
21/4/2015 Dr. Ahmad Yousef
3D Building Model
5 - 3D Model Reconstruction
21/4/2015 Dr. Ahmad Yousef
3D Building Model
5 - 3D Model Reconstruction
21/4/2015 Dr. Ahmad Yousef
3D Building Model
5 - 3D Model Reconstruction
21/4/2015 Dr. Ahmad Yousef
3D Building Model
5 - 3D Model Reconstruction
21/4/2015 Dr. Ahmad Yousef
3D Building Model
5 - 3D Model Reconstruction
21/4/2015 Dr. Ahmad Yousef
3D Building Model
5 - 3D Model Reconstruction
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Example 1
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Example 1
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Example 1
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Example 2
Minimum area
threshold = 5 m2
Minimum area
threshold = 3 m2
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Example 3
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Test Area
21/4/2015 Dr. Ahmad Yousef
3D Building Model
Error Sources
21/4/2015 Dr. Ahmad Yousef
Summary
Conclusion & Final Thoughts...
• Minimum Block Classification (MBC) Model was successfu...
21/4/2015 Dr. Ahmad Yousef
Summary
Conclusion & Final Thoughts...
o Minimum Block Classification (MBC) Model was successfu...
21/4/2015 Dr. Ahmad Yousef
Thank You
Share What You Can To Benefit The Others
Ahmad Yousef (yousef@dii-eumena.com)
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Buildings3 d gThe Use of Geographical Information Systems for 3D Urban Models Reconstruction from Aerial Lidar Data

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Urban models are highly useful in city planning and 3D visualization. These models include different items such as bare earth, buildings, trees, roads, and other non-terrain objects. In recent years, the demand of the urban model has increased, and the three dimensional models that have been generated by different methods can be transferred into geographic information systems (GIS) easily and used as a base for GIS applications including urban planning, architecture, and environmental modeling.
Light detection and ranging (lidar) technology has continued to draw great attention from GIS users. Because large volumes of lidar data can be produced, studies have been made toward the goal of handling lidar data in GIS software for classification or object extraction. This presenation makes the attempt to propose methods and develop tools for bare earth extraction and 3D building reconstruction models by integrating lidar points.

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Buildings3 d gThe Use of Geographical Information Systems for 3D Urban Models Reconstruction from Aerial Lidar Data

  1. 1. 21/4/2015 Dr. Ahmad Yousef The Use of GIS for 3D Urban Models Reconstruction Based on Aerial Lidar Data Dr. Ahmad Yousef
  2. 2. 21/4/2015 Dr. Ahmad Yousef • Overview • Objectives & Goals • Digital Terrain Model Extraction • 3D Building Model Reconstruction • Conclusion & Final Thoughts AGENDA
  3. 3. 21/4/2015 Dr. Ahmad Yousef Pollution, Cairo Visualization, Dubai Pollution, Moscow Flood, Pakistan Visualization, Los Angeles City Planning, Stuttgart Flood, Mexico • GIS has traditionally been 2D technology. • New product and technology make us reconsider the role of 3D. • It is widely recognized that 3D models are necessary. Overview Why 3D GIS …
  4. 4. 21/4/2015 Dr. Ahmad Yousef Year : 2050 66% Year : 2014 54% Urban Population World Source: UN DESA’s Population Division of Global Population o The overall growth of the world’s population could add another 2.5 billion people to urban populations by 2050 o 90 percent of the increase concentrated in Asia and Africa Overview Why urban area …
  5. 5. 21/4/2015 Dr. Ahmad Yousef Overview Why lidar data … Waldkirch, Germany
  6. 6. 21/4/2015 Dr. Ahmad Yousef Overview Workshop Objectives & Goals
  7. 7. 21/4/2015 Dr. Ahmad Yousef Overview Workshop Objectives & Goals
  8. 8. 21/4/2015 Dr. Ahmad Yousef Overview Workshop Objectives & Goals 1. Introduce a fast and simple integrated Digital Terrain Model (DTM) extraction framework in a GIS environment.
  9. 9. 21/4/2015 Dr. Ahmad Yousef Overview Workshop Objectives & Goals 1. Introduce a fast and simple integrated Digital Terrain Model (DTM) extraction framework in a GIS environment. 2. Introduce a developed GIS approach for reconstructing of the 3D building models from lidar point clouds.
  10. 10. 21/4/2015 Dr. Ahmad Yousef Digital Terrain Model Extraction How to classify lidar data into terrain and off-terrain points?
  11. 11. 21/4/2015 Dr. Ahmad Yousef • Filtering means classification of points into terrain and off-terrain. • Bare earth is assumed to be continuous surface. • Filtering In/Out data: – Point list – Grid – Triangulated Irregular Network - TIN DTM Extraction Filtering lidar data
  12. 12. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Esri Terrain Dataset Surface geometry at different resolution (TINs) – TIN is acronym for triangulated irregular network. Level of Detail-Pyramid LoD x Pyramid Type: I. WINDOWSIZE II. ZTOLERANCE parameter: I. ZMIN II. ZMAX III. ZMEAN IV. ZMINMAX
  13. 13. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Esri Terrain Dataset
  14. 14. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Esri Terrain Dataset
  15. 15. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Esri Terrain Dataset
  16. 16. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Esri Terrain Dataset
  17. 17. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Minimum Block Classification - MBC Window Block Bare Earth Surface Input Points Dataset [Geodatabase], Input Window Size, Cell Size (≈ Points Average Distance) Output Ground Points, DTM Window Block
  18. 18. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Minimum Block Classification - MBC Input Points Dataset [Geodatabase], Input Window Size, Cell Size (≈ Points Average Distance) Output Ground Points, DTM 1 2 3 5 Window Size Z-threshold 32 3.2 16 1.6 8 0.8 4 0.4 2 0.2 4
  19. 19. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Minimum Block Classification - MBC Input Points Dataset [Geodatabase], Input Window Size, Cell Size (≈ Points Average Distance) Output Ground Points, DTM Convert Terrain to TIN Smoothing Umbrella Filter
  20. 20. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Digital Surface Model
  21. 21. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Digital Terrain Model
  22. 22. 21/4/2015 Dr. Ahmad Yousef Digital Surface Model Shaded Relief DTM Extraction Forest Dataset … Digital Terrain Model Shaded Relief
  23. 23. 21/4/2015 Dr. Ahmad Yousef 45m x 35m DTM Extraction Urban Dataset … 5 750 000 Points
  24. 24. 21/4/2015 Dr. Ahmad Yousef DTM Extraction Urban Dataset …
  25. 25. 21/4/2015 Dr. Ahmad Yousef 3D Building Models Reconstruction How to fulfill the gap between lidar data and building models ? How to minimize the number of points that represent a building ?
  26. 26. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Buildings Shapes … Redlands, USA. Source : Google maps
  27. 27. 21/4/2015 Dr. Ahmad Yousef 3D Building Model No Comments … Venezuela. Barrio Petare, Caracas. Source: A sustainable approach to problems in urban squatter developments
  28. 28. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Level of Details LoD • Building model is the representation used for describing the form of building. • The complexity of a 3D building model is known as the level of details (LoDs). Source: : Open Geospatial Consortium CityGML Implementation Specification 1.0,20.8 2008 Level of Details Data Processing LoD 1 : Flat Roofs LoD 2 : Roof Type LoD 3 : Real Roof Shape LoD 4 : Interior
  29. 29. 21/4/2015 Dr. Ahmad Yousef Model Structure Based – Model Derive 3D Building Model Modeling Approaches • Model Database. • The final roof shape is always topologically correct. • Complex roof shapes cannot be reconstructed. 3D Building Models Database Flat Desk Gable Hipped Mansard PyramidGambrel
  30. 30. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Modeling Approaches Source: International Summer School “Digital Recording and 3D Modeling”. 3D Building Models Database Flat Desk Gable Hipped Mansard PyramidGambrel
  31. 31. 21/4/2015 Dr. Ahmad Yousef Data Structure Based – Data Derive 3D Building Model Modeling Approaches • Roof described by planar faces. • Partitioning the given ground plan and find the most appropriate plane segment to each partition. Source: International Summer School “Digital Recording and 3D Modeling”.
  32. 32. 21/4/2015 Dr. Ahmad Yousef Input for Data Derive Model 3D Building Model Modeling Approaches I. Points based – Points may belong to several planes. II. Raster based – Information content is decreased due to interpolation. III. TIN based – To avoid loss of information due to interpolation, all operations are performed on the Delaunay triangulation of the original height points. – Requires more analysis.
  33. 33. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Building Model Elements Planar Patches Wall Footprint Planar Face TIN Triangles Lidar Roof Boundary
  34. 34. 21/4/2015 Dr. Ahmad Yousef 5 Processing Steps :- 3D Building Model Framework … 1. Generate Triangle Irregular Network - TIN 2. Extract Roof Planar Patches i. Normal Vector Estimation ii. Segmentation & Region Growing 3. Detection of Planar Roof Faces i. Least Square Plane Fitting ii. Merging Planar Patches 4. Intersection of Roof Planes 5. 3D Model Reconstruction
  35. 35. 21/4/2015 Dr. Ahmad Yousef
  36. 36. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 1 - Triangle Irregular Network
  37. 37. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 1 - Triangle Irregular Network
  38. 38. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches A.X + B.Y + C.Z + D = 0 N=(A,B,C)
  39. 39. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Normal Vector Estimation 1 Ring Neighborhood 2 Rings Neighborhood
  40. 40. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Normal Vector Estimation
  41. 41. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Normal Vector Estimation
  42. 42. 21/4/2015 Dr. Ahmad Yousef 1 Ring Neighborhood 3D Building Model 2 - Extract Roof Planar Patches Normal Vector Estimation
  43. 43. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Normal Vector Estimation 2 Rings Neighborhood
  44. 44. 21/4/2015 Dr. Ahmad Yousef 2 Rings Neighborhood 3D Building Model 2 - Extract Roof Planar Patches Normal Vector Estimation
  45. 45. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Segmentation & Region Growing Apply region growing to find roof patches
  46. 46. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Segmentation & Region Growing
  47. 47. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Segmentation & Region Growing
  48. 48. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 2 - Extract Roof Planar Patches Segmentation & Region Growing
  49. 49. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 3 - Detection of Planar Roof Faces
  50. 50. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 3 - Detection of Planar Roof Faces Vertical Triangles All triangles with slope greater than 60 are considered as vertical patches
  51. 51. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 3 - Detection of Planar Roof Faces Least Square Plane Fitting A * X + B * Y + C * Z = D The Plane Normal is given by : N = (A,B,C)
  52. 52. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 3 - Detection of Planar Roof Faces Intersection of adjacent patches A * X + B * Y + C * Z = D
  53. 53. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 3 - Detection of Planar Roof Faces Merging Planar Patches
  54. 54. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 4 - Intersection of Roof Planes Patch 1 2 3 4 5 6 7 1 YES YES YES YES 2 YES YES YES 3 YES YES 4 YES YES 5 YES YES 6 YES YES YES 7 YES Plane Adjacency Matrix
  55. 55. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 4 - Intersection of Roof Planes
  56. 56. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 4 - Intersection of Roof Planes
  57. 57. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 5 - 3D Model Reconstruction
  58. 58. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 5 - 3D Model Reconstruction
  59. 59. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 5 - 3D Model Reconstruction
  60. 60. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 5 - 3D Model Reconstruction
  61. 61. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 5 - 3D Model Reconstruction
  62. 62. 21/4/2015 Dr. Ahmad Yousef 3D Building Model 5 - 3D Model Reconstruction
  63. 63. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Example 1
  64. 64. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Example 1
  65. 65. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Example 1
  66. 66. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Example 2 Minimum area threshold = 5 m2 Minimum area threshold = 3 m2
  67. 67. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Example 3
  68. 68. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Test Area
  69. 69. 21/4/2015 Dr. Ahmad Yousef 3D Building Model Error Sources
  70. 70. 21/4/2015 Dr. Ahmad Yousef Summary Conclusion & Final Thoughts... • Minimum Block Classification (MBC) Model was successfully implemented in GIS environment. • Advantages of MBC Model includes : – Fixed number of processing loops. – Capable of capturing and removing the major terrain features. – Although building size and shape present a challenge for many other filtering algorithms, they do not significantly hinder the MBC algorithm when using the proper window size and threshold.
  71. 71. 21/4/2015 Dr. Ahmad Yousef Summary Conclusion & Final Thoughts... o Minimum Block Classification (MBC) Model was successfully implemented in GIS environment. o 3D building reconstruction models from lidar data was developed from constructing a roof surface geometry. o 3D building reconstruction models result affected by  Minimum area threshold  Points distribution  Shape complexity o The processing time varies and is dependent on the shape of the building, start from 5 seconds for simple buildings to 30 seconds for complex buildings.
  72. 72. 21/4/2015 Dr. Ahmad Yousef Thank You Share What You Can To Benefit The Others Ahmad Yousef (yousef@dii-eumena.com)

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