METRIC ALIGNMENT OF LASER RANGE SCANS AND CALIBRATED IMAGES USING LINEAR STRUCTURES

Transcription

1 METRIC ALIGNMENT OF LASER RANGE SCANS AND CALIBRATED IMAGES USING LINEAR STRUCTURES Lorenzo Sorg CIRA the Italan Aerospace Research Centre Computer Vson and Vrtual Realty Lab.

2 Outlne Work goal Work motvaton State of the art Calbraton model Implementaton detals Results

3 Work Objectve The goal s the estmaton of rgd moton transformaton between a Laser Range Scanner and an Imagng System (External Calbraton), whch s needed to acheve the accurate algnment of the 3D range profles on a matched vdeo. ( R, t) : R SO(3), t 3

4 Work Motvaton The accurate co-regstraton of heterogeneous data s a fundamental requrement for a robotc systems, performng autonomous operatons: Object pose estmaton, dockng, trackng, graspng, etc.; Rover Autonomous Navgaton, Laser aded vsual SLAM; Geometrc documentaton and object nspecton; Sensor aded exposure of magng systems; anytme range profles and mage raster maps need to be jontly processed to gather knowledge about the surroundng envronment.

5 State of the art!! No extensve lterature s avalable on ths topc. I. P. Núñez and al. - Data Fuson Calbraton for a 3D Laser Range Fnder and a Camera usng Inertal Data. (ECMR 2009). II. R. Unnkrshnan and al. - Fast extrnsc calbraton of a laser rangefnder to a camera. Techncal Report CMU-RI-TR III. L. Huang and al. - A Novel Mult-Planar LIDAR and Computer Vson Calbraton Procedure Usng 2D Patterns for Automated Navgaton. IEEE Intellgent Vehcle Symposum IV. S. Kumar and al. - Sensor Fuson of Laser & Stereo Vson Camera for Depth Estmaton and Obstacle Avodance. Int. Journal of Computer Applcatons. Num. 26:3. Need of a mddle-man sensor (AHRS); Algorthm do not cope wth 1D lasers scanners; Geometrc entty used for calbraton may not be easly and accurately extracted from raw data (planes); Not real calbraton (generaton of rough navgaton maps);

6 Calbraton Model SE(3) H C S L Geometrc Entty Camera Laser Scanner Back-projected plane l Image lne l P H P C S C S C P

7 Calbraton Model L 1,..., N C l C 1,..., N 1,..., N S P 1,..., N H SC mn HSE(3) 1.. N d C SC S C T S, H P l R P t 1.. N

8 Calbraton Tool Implementaton Detals

9 Implementaton Detals Lne extracton from mages Lne Detecton by Hough Transform (RED) Lne Refnement Based on GL 10 Flterng (GREEN) Bsector Segment Extracton (YELLOW) C l 1,..., N L.Sorg - Edgelet Trackng usng Gauss-Laguerre Crcular Harmonc Flters. Paper submtted to IEEE ICIP 2011.

10 Implementaton Detals Lne extracton from range profles Spot Detecton by maxmum curvature k r 2 2r' 2 rr'' r r' 2 Spot Refnement by Local Parabolc Fttng S P 1,..., N

11 Implementaton Detals External Calbraton estmaton External calbraton ntalzaton by vsual nspecton ( easy! ) R z H dp J d d t P R dr l P H d d S T C S C S C 0, Implct enforcement of SO(3) constrant n LM scheme; Analytcal computaton of error terms Jacoban. T T T S T C d S T C d d dp I t P R l J t P R l d 3 0

12 Results on synthetc data Synthetcally generated scene gven by 20 lnes n 3D space; Image ponts corrupted by addtve whte Gaussan nose; Nose std.dev. rangng n the nterval [0-10] px; 100 test for each nose level. e rot R T Rˆ 180 [deg] e tr t tˆ 100 t [%] N N

13 Results on synthetc data Synthetcally generated scene gven by N lnes n 3D space; Image ponts corrupted by addtve whte Gaussan nose wth fxed ntensty ( 3 px std.dev.) ; Numer of lnes rangng n the nterval [5-200]; 100 test for each scene complexty level. e rot R T Rˆ 180 [deg] e tr t tˆ 100 t [%] Nlnes Nlnes

14 Laser Camera system Results on real system Pont Grey Chameleon 1296(H) x 964(V) 6 mm lens (43 H Fov) Hokuyo Scannng Range Fnder UTM-30LX 30m x 270 scannng range 0.25 angular resoluton Accuracy ±30mm [ 0.1m : 10 m ]

15 Results on real system Optmzaton Process dp dp 0 Err Err 0 t

16 Results on real system Optmzaton Process

17 Results

18 Results

19 Results

20 Conclusons A technque to estmate the External Calbraton of a Laser-Camera system has been proposed; The technque uses 3D straght lnes as calbraton geometrcal entty; Support algorthms have been defned to accuratly collect the calbraton dataset from laser profles and mages; The algorthm provdes a core utlty for any multsensor platform performng some robotc operaton (object trackng, pose estmaton, scene exploraton, geometry retrval, etc. ); The algorthm s sutable for offlne calbraton and onlne calbraton recovery; Straghforward extenson to the case of stereocamera or multcamera.

21 Thank you for attenton!