METHOD FOR SIMULATING THE EFFECTS OF THE OPTICAL DISTORTIONS OF A WINDSHIELD ON THE IMAGE RECORDING QUALITY OF A DIGITAL IMAGE RECORDING DEVICE

1 . A computer implemented method for simulating effects of optical distortions of a windshield on an image recording quality of a digital image recording device, wherein said method takes as input a measured optical quality function related to the optical distortions of the windshield and an input image of a landscape likely to be recorded by a digital image recording device through said windshield, wherein said method provides as output an image of said input image of a landscape as viewed through said windshield, wherein said method comprises the following steps:

(a) modelling at least one sheet of transparent mineral glass comprising two main parallel faces, wherein a surface of at least one of said two main parallel faces is textured with the measured optical quality function, and wherein the sheet of transparent mineral glass is placed in front of the input image of the landscape and is inclined, with respect to said input image an installation angle of said windshield in a transporting vehicle;

(b) calculating, with a stochastic ray tracing method, a global illuminance arriving through the modelled inclined sheet of transparent mineral glass from the input image of the landscape as a light source; and

(c) calculating a 3D projection of the global illuminance from a view frustum of a virtual camera with an optical camera model of said virtual camera, wherein said virtual camera is placed in front of an opposite main face of the sheet of transparent mineral glass with respect to the input image of the landscape used as a light source and at a position corresponding to an installation position of the digital image recording device.

2 . The computer implemented method according to claim 1 , wherein the measured optical quality function related to the optical distortions of the windshield is a measured transmitted wavefront error of the windshield, measured surfaces profiles and/or a measured distribution of complex refractive index.

3 . The computer implemented method according to claim 1 , wherein the input image of the landscape is at a finite distance of the modelled sheet of transparent mineral glass.

4 . The computer implemented method according to claim 1 , wherein the input image of the landscape is digitally preprocessed as an environment map projected onto an inside side of an environment sphere centered on the virtual camera.

5 . The computer implemented method according to claim 1 , wherein, in step (a), the sheet of transparent mineral glass is modeled so that said sheet of transparent mineral glass represents only a demarcated zone of the windshield in front of which a digital image recording device is placed.

6 . The computer implemented method according to claim 1 , wherein, in step (a), the sheet of transparent mineral glass is modelled so that the global illuminance calculated at step (c) is only the global luminance arriving through the part of modelled sheet of transparent mineral glass which corresponds to a demarcated zone of the windshield through which a digital image recording device records an image.

7 . The computer implemented method according to claim 1 , wherein the optical camera model of the virtual camera is a camera projection matrix, a point-spread function, an optical transfer function or a real modelling of each interface of the different optics of the camera lens of the digital image recording device.

8 . The computer implemented method according to claim 1 , wherein, before step (a), the input image of a landscape is digitally preprocessed first with a color filter array, and/or second with a demosaicing algorithm, in particular with a nearest-neighbor interpolation kernel.

9 . A computer implemented method according to claim 1 , wherein the texture of the textured surface is modeled with a bump map or a displacement map.

10 . A computer implemented method according to claim 1 , wherein the stochastic ray tracing method is a stochastic path tracing method.

11 . A data processing system comprising a processor and a memory coded with instruction for carrying out a method according to claim 1 .

12 . A non-transitory computer readable medium comprising instructions which, when the instructions are executed by a computer, cause the computer to carry out a method according to claim 1 .

13 . A method comprising performing a method according to claim 1 for evaluating an optical quality of a windshield for a use with a digital image recording device.

14 . A method comprising performing a method according to claim 1 for calibrating digital image recording device of an automated driving and advanced safety system.

15 . A process for evaluating performances of an object detection and classification algorithm of an automated driving and advanced safety system, wherein said process comprises the following steps:

(a) providing a set of measured optical quality functions related to optical distortions of a set of windshields;

(b) providing a set of images of landscapes likely to be recorded by a digital image recording device through the windshield of said set of windshields;

(c) using a computer implemented method according to claim 1 for each image of the set of images of landscapes and each measured optical quality function I 3001 of the set measured optical quality functions related to the optical distortions, in order to provide a set of images of images of a landscape as viewed through the windshield of said set of windshields;

(d) feeding the set of images obtained at step (c) to an object detection and classification algorithm of an automated driving and advanced safety system;

(e) monitoring performance parameters in the object detection and classification of said algorithm while the algorithm is processing the set of images fed at step (d).

16 . The method according to claim 13 , wherein the digital image recording device is a digital image recording device of an automated driving and advanced safety system.