Transcript The fusion process of LiDAR and map data to generate 3D

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)
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EXAMPLE IN FIGURES
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BUILDINGS
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THE QUESTIONS
 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?
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FUSING MAP AND LASER DATA
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SELECT LASER POINTS PER MAP POINT, PER POLYGON
 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
HYDROCITY
PRODUCE 3D MODEL FOR HYDROLOGICAL APPLICATIONS
 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
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HYDROCITY
OBJECT BASED
 Per object: height, infiltration capacity, surface roughness
 Interpolated to grid for run off modelling
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3DIMGEO
1:1.000
 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.
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FME - 3DIMGEO TOOLS - FME
 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
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3DTOP10NL
 1:10.000
 Fused with AHN-2 (~8 p/m^2)
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IMPLICATIONS OF FUSION
 TOP10NL: topographic
representation, geometric accuracy 2
m
 AHN-2: geometric 3D representation,
geom acc < 0.5 m, 8-10 p/m2
 Aim for selecting ‘correct’ points
 Do we need all laser points?
RULES TO CALCULATE OBJECT HEIGHT
Class
Lidar data taken 3D Representation type Initial height of object points Surface description
from
/ Semantic constraint on boundary
Water
Ground
Horizontal plane
All object points are set to
average height
Roads
Ground
Locally planar
Each object point is determined Determined by triangulation
by height of local fitted plane of boundary object points
Terrain
Ground
May vary locally
points are inserted
Each object point is determined Lidar
polygon, followed by
by height of local fitted plane inside
constrained triangulation
Buildings Non-ground
Horizontal plane, LoD 1
All object points are set to
average height
Forest
May vary locally
points are inserted
Each object point is determined Lidar
inside
polygon, followed by
by height of local fitted plane constrained
triangulation
Non-ground
Determined by triangulation
of boundary object points
Determined by triangulation
of boundary points
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RULES TO COMBINE HEIGHT OF NEIGHBOURING
POLYGONS
Water
Road
Terrain
Building
Forest
Water
Road
Terrain
Both keep own
height
Both own height,
create additional Take water
polygon below height
road
Building
Forest
Both keep own Both keep own
height, create
height, create
wall in-between wall in-between
keep own Both keep own
Average if close Take road height Both
height,
create
height, create
in height
wall in-between wall in-between
keep own Both keep own
Take average of Both
height,
create
height, create
both heights
wall in-between wall in-between
Both keep own
height
Both keep own
height
Both keep own
height
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THE QUESTIONS
AND THE FRUSTRATING ANSWERS
 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.
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NEAR FUTURE
 Kadaster will go for 3DTOP10NL
 3D IMGeo tools are open (since April 2013) and integrated into FME
 Nice link between Geo practice and research
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MORE INFO
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