Berlin Institute of Technology Department of Geodesy and Geoinformation Science. Plane Based Free Stationing for Building Models

Transcription

1 Berlin Institute of Technology Department of Geodesy and Geoinformation Science Plane Based Free Stationing for Building Models Christian Manthe, Germany Introduction Motivation Plane based building model Plane detection in point clouds Plane based free stationing Transformation parameter Corresponding planes Geometrical adaption Conclusions Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 1

2 Motivation 3D Building Models are used to Construct buildings all entities are designed Geometry is errorless given Manage existing buildings Current description Model geometry should based on real measurements Planning of modifications or interior decoration The model geometry has to be sufficient comparing to given tolerance values Christian Manthe - Plane Based Free Stationing for Building Models Motivation Searched : Method to update the model geometry Quality control of building model (precision and reliability) model Point cloud Plane based representation plane extraction plane set Plane based free stationing for transformation and searching of corresponding planes Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011

3 Plane based Building Model Plane based representation Topology Validation problem Geometry Christian Manthe - Plane Based Free Stationing for Building Models Plane based Building Model Building representations based on Solids (civil engineering) Divided spaces (surveying) Validation in steps: Step 1: Separate validation Closed spaces or solids Aggregation of related entities to solve the Euler formula v-e+f+h-r= (vertices v, edges e, faces f, holes h, inner loops r) Step : Joined validation Nodes intersect by more then planes Independent plane normal's more then Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 3

4 XML-file of a cuboid Geometry Model of a cuboid Nodes Edges Edges Mesh Mesh Plane Plane Normal Vector Normal Vector - Parameter Plane Detection Automated feature extraction in point clouds Relationship between points and planes is given (total station) Neighborhood of the points is given (laser scanning) without assumptions or advance information Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 4

5 Plane Detection Step 1: Segmentation (adjacent point groups) Storing the points in a kd-tree Create a space index with respect to a fixed number of points (cubed subspace) Christian Manthe - Plane Based Free Stationing for Building Models Plane Detection Step : Determination of planes Using Random Sample Consensus (RANSAC) paradigm To extract multiple instances Number of useful tries l depends on the failure rate f and the number of planes k. (l=ln(1/p)*k ) 1. After l tries the best represented plane parameter are chosen. Adjustment (gives the parameter and stochastic information) 3. The assigned points were canceled for the next detection The procedure will run until k planes were extracted (subspace) Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 5

6 Plane Detection Step 3: Merging the local planes to a global plane set Use the F-Test to detect identical planes Using the index structure of the subspaces At the end of the feature extraction A planes set is given Stochastic information is accessible for all planes in the plane set Christian Manthe - Plane Based Free Stationing for Building Models plane based free stationing model Plane based representation Point cloud plane extraction plane set Plane based free stationing for transformation and searching of corresponding planes Christain Manthe - 6/1/011 1 Marrakech, Morocco, 18 May 011 6

7 Estimation of the Transformation parameter plane model system d n v n r 1 r 0 = n x r plane d plane based free stationing d 1 plane 1 cloud system r v x F = n 1 d 1 0 = n r x r plane d r v n = R n 1 r r r x plane = RxF + t r r 0 = nx plane d r v r 0 = n ( RxF + t ) d r r r 0 = n ( Rn1d1 + t ) d r r r 0 = n ( n d + t d 1 ) r r 0 = d + n t d 1 Christian Manthe - Plane Based Free Stationing for Building Models plane based free stationing Semi-automatic matching of corresponding planes 1. Manual assignment of more than two corresponding planes. Calculation of the transformation parameter between the model system and the point cloud system 3. Transformation of the plane set into the model system to find more candidates for corresponding planes 4. Testing the candidates and extending the plane based model 5. Rerun step 1 4 until no more identical planes were found Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 7

8 plane based free stationing The plane based building model and its upgrad with respect to the corresponding planes Each cloud plane is attributed with it transformation to the model For each plane it stochastic information is accessible Plan assignments are stored in a entity relationship model Christian Manthe - Plane Based Free Stationing for Building Models Geometrical adaption model Plane based representation Point cloud plane extraction plane set Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 8

9 Geometric adaption New plane information is used to update the geometry Example: cuboid updated with new normal vector parameter Christian Manthe - Plane Based Free Stationing for Building Models Conclusions Plane based representation of building models is useful to update the geometry of an building model A method to extraction planes in point clouds with no advanced information is implemented (plugin for Google Sketchup) After a feature extraction a plane based free stationing (registration) can be used to update building geometry Because of the given stochastic information by the cloud planes stochastic information for the model is accessible If the local precision of the model is no enough new observations can be measured and used for updating the geometry without influencing the model topology Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May 011 9

10 Thanks for your attention! Christian Manthe - Plane Based Free Stationing for Building Models Marrakech, Morocco, 18 May