Geometric calibration of multi-sensor image fusion system with thermal infrared and low-light camera

Abstract

A calibration platform for geometric calibration of multi-sensor image fusion system is presented in this paper. The accurate geometric calibration of the extrinsic geometric parameters of cameras that uses planar calibration pattern is applied. For calibration procedure specific software is made. Patterns used in geometric calibration are prepared with aim to obtain maximum contrast in both visible and infrared spectral range -using chessboards which fields are made of different emissivity materials. Experiments were held in both indoor and outdoor scenarios. Important results of geometric calibration for multi-sensor image fusion system are extrinsic parameters in form of homography matrices used for homography transformation of the object plane to the image plane. For each camera a corresponding homography matrix is calculated. These matrices can be used for image registration of images from thermal and low light camera. We implemented such image registration algorithm to confirm accuracy of geometric calibration procedure in multi-sensor image fusion system. Results are given for selected patterns -chessboard with fields made of different emissivity materials. For the final image registration algorithm in surveillance system for object tracking we have chosen multi-resolution image registration algorithm which naturally combines with a pyramidal fusion scheme. The image pyramids which are generated at each time step of image registration algorithm may be reused at the fusion stage so that overall number of calculations that must be performed is greatly reduced.

Infrared Camera Geometric Calibration: A Review and a Precise Thermal Radiation Checkerboard Target

“…Apart from printing the square checkerboard pattern, few studies analyzed the effectiveness of two different taped calibration targets, an aluminum plate with high emissivity square tape, and cardboard with low emissivity square aluminum foil tape, with the targets being heated using a monitor display [ 36 , 37 ]. Similarly, a study involved the geometric calibration of thermal cameras, part of a target tracking project, and used a square checkerboard pattern made of a white highly emissive tape placed on an aluminum foil base [ 38 ].…”

“…With radial and tangential lens distortions affecting the images, imprecise calibration results in further errors that affect the certainty of the geometric calibration study [ 56 , 57 ]. While few studies described the detailed construction of the used geometric calibration targets [ 6 , 19 , 25 , 37 , 47 , 49 , 51 ], several studies shared little to no details on how the calibration rigs were constructed. Furthermore, many studies involved the manual construction of the targets, such as the manually cut square grids [ 31 ] or the manual aluminum foil and tape placements on the targets [ 19 , 33 , 34 , 36 , 38 ].…”

Drone-Enabled Multimodal Platform for Inspection of Industrial Components

“…External-heating calibration board needs an external heat source to provide the required thermal contrast. Peric et al investigated using two types of boards as an initial step for the fusion of thermal and visible images [55]. They used polished aluminum as a base and black opaque insulating tape for the first board.…”

Passive calibration board for alignment of VIS-NIR, SWIR and LWIR images

“…They obtained interesting results for outdoor scenes, but they need to take precautions to minimize specular reflections on their extremely low emissivity (0.09) copper material. The similar calibration rigs of Peric et al [5] and Campo et al [6], built with aluminum foil, also suffer from 10.21611/qirt.2016.124 specular reflections. Harguess et al [7] provided an interesting study about the choice of a calibration rig and its calibration pattern, in a context of uncontrolled outdoor scenes and wide baseline between cameras.…”