THE FUSION PROCESS OF LIDAR AND MAP DATA TO GENERATE 3D CITY AND LANDSCAPE MODELS SANDER OUDE ELBERINK GEOSPATIAL WORLD FORUM 16 MAY 2013

 Generation of nationwide 3D city and landscape models using national datasets:  1:1.000, BGT, fused with AHN-2 (~8 p/m^2)  1:10.000, TOP10, fused with AHN-2 (~8 p/m^2)  Fusion process  Research questions  Hydrocity (1:1.000)  3DIMGeo (1:1.000)  3DTOP10NL (1:10.000) 2

EXAMPLE IN FIGURES 3

BUILDINGS 4

 Which lidar points have to be used to transfer the height to an object?  How to use the semantics of the map data?  How to assign a height to a point, boundary or surface?  What is the quality of that height?  How to deal with noise in both the map and lidar data? THE QUESTIONS 5

FUSING MAP AND LASER DATA 6

 Transfer height from selected points to map point  In general resulting in at least 2 heights per map point.  What to do with the differences?  Semantics between classes SELECT LASER POINTS PER MAP POINT, PER POLYGON

 See also presentation of Mark Kroon Neo  Aim was to keep small relative height differences  (but not the ones caused by ‘noise’)  Curbstones  Boundary between 2 infrastructural polygons (road, sidewalk).  Function of object in addition to class label HYDROCITY PRODUCE 3D MODEL FOR HYDROLOGICAL APPLICATIONS 8

 Per object: height, infiltration capacity, surface roughness  Interpolated to grid for run off modelling HYDROCITY OBJECT BASED 9

 As a product of 3D Pilot, start of 3D SIG NL (see presentation of Jantien Stoter).  Based on IMGeo, CityGML standards.  Workbench in FME, in cooperation with con terra GmbH (Christian Dahmen).  LoD0, LoD1 and LoD2. 3DIMGEO 1:

 Use FME to (summary)  Read and validate source data: CityGML 2D IMGeo + LiDAR (AHN-2)  'Point-On-Polygon' operation (assign laser data to polygons)  Run + manage the complete workflow -> Single User Interface  Use '3D IMGeo tools' developed by U Twente to:  Prepare map data and laser data for the 3D reconstruction.  Assign height to the map boundaries for a LoD0 terrain description.  Assign a height description inside the 3D polygons. Results are TIN surfaces at LoD0.  Calculate LoD1 or ‘LoD2’ buildings and forest  Use FME again to write result data: CityGML 3D IMGeo FME - 3DIMGEO TOOLS - FME 11

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 1:  Fused with AHN-2 (~8 p/m^2) 3DTOP10NL 13

 TOP10NL: topographic representation, geometric accuracy 2 m  AHN-2: geometric 3D representation, geom acc < 0.5 m, 8-10 p/m 2  Aim for selecting ‘correct’ points  Do we need all laser points? IMPLICATIONS OF FUSION

Class Lidar data taken from 3D Representation type / Semantic constraint Initial height of object points on boundary Surface description WaterGroundHorizontal plane All object points are set to average height Determined by triangulation of boundary object points RoadsGroundLocally planar Each object point is determined by height of local fitted plane Determined by triangulation of boundary object points TerrainGroundMay vary locally Each object point is determined by height of local fitted plane Lidar points are inserted inside polygon, followed by constrained triangulation BuildingsNon-groundHorizontal plane, LoD 1 All object points are set to average height Determined by triangulation of boundary points ForestNon-groundMay vary locally Each object point is determined by height of local fitted plane Lidar points are inserted inside polygon, followed by constrained triangulation RULES TO CALCULATE OBJECT HEIGHT 17

RULES TO COMBINE HEIGHT OF NEIGHBOURING POLYGONS 18 WaterRoadTerrainBuildingForest Water Both keep own height Both own height, create additional polygon below road Take water height Both keep own height, create wall in-between Road Average if close in height Take road height Both keep own height, create wall in-between Terrain Take average of both heights Both keep own height, create wall in-between Building Both keep own height Forest Both keep own height

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 Which lidar points have to be used to transfer the height to an object?  Depends on the object.  How to use the semantics of the map data?  Depends on the map/application.  How to assign a height to a point, boundary or surface?  Depends on the object.  What is the quality of that height?  Depends on the workflow.  How to deal with noise in both the map and lidar data?  Deal with it. THE QUESTIONS AND THE FRUSTRATING ANSWERS 20

 Kadaster will go for 3DTOP10NL  3D IMGeo tools are open (since April 2013) and integrated into FME  Nice link between Geo practice and research NEAR FUTURE 21

MORE INFO 22