Getting param of left camera(ir sensor) using SDK2.0 is different from using CustomRW tool.

[LW-SCU]

---

Required Info
Camera Model	D345i
Firmware Version	05.12.03.00
Operating System & Version	win10
Kernel Version (Linux Only)	(e.g. 4.14.13)
Platform	PC
SDK Version	2.33.1
Language	C++
Segment	{Robot/Smartphone/VR/AR/others }

Issue Description

Getting param of left camera(ir sensor) using SDK2.0 is different from using CustomRW tool.
I got param of left camera by SDK2.0,this is my code:

int main(){
    pipeline pipe;
    config cfg;
    cfg.enable_stream(RS2_STREAM_INFRARED,1,1280,800,RS2_FORMAT_Y8,15);
    pipe.start(cfg);
    {
        int i = 10;
        while(i--) pipe.wait_for_frames();
    }

    auto in = pipe.wait_for_frames().get_infrared_frame(1).get_profile().
            as<video_stream_profile>().get_intrinsics();
    cout<<"FocalLengthLeft:"<<in.fx<<"\t"<<in.fy<<endl;
    cout<<"PrincipalPointLeft:"<<in.ppx<<"\t"<<in.ppy<<endl;
    cout<<"DistortionLeft:"<<endl;
    for(int i = 0;i<5;i++){
        cout<<intrinsic.coeffs[i]<<endl;
    }
    pipe.stop();
    return 0;
}
output:
FocalLengthLeft:640.041	640.041
PrincipalPointLeft:635.598	399.094
DistortionLeft:
0
0
0
0
0

I got a param xml file using CustomRW tool.

<?xml version="1.0"?>
<Config>
    <param name = "ResolutionLeftRight">
        <value>1280</value>
        <value>800</value>
    </param>
    <param name = "FocalLengthLeft">
        <value>635.805</value>
        <value>636.461</value>
    </param>
    <param name = "PrincipalPointLeft">
        <value>634.809</value>
        <value>400.025</value>
    </param>
    <param name = "DistortionLeft">
        <value>-0.0520426</value>
        <value>0.0531889</value>
        <value>-0.0017655</value>
        <value>-0.000307534</value>
        <value>-0.0154513</value>
    </param>
    <param name = "FocalLengthRight">
        <value>635.986</value>
        <value>636.569</value>
    </param>
    <param name = "PrincipalPointRight">
        <value>632.48</value>
        <value>402.725</value>
    </param>
    <param name = "DistortionRight">
        <value>-0.0503853</value>
        <value>0.0503416</value>
        <value>-0.00142165</value>
        <value>-0.000518733</value>
        <value>-0.0139281</value>
    </param>
    <param name = "RotationLeftRight">
        <value>0.999944</value>
        <value>0.00105141</value>
        <value>-0.0104881</value>
        <value>-0.00102754</value>
        <value>0.999997</value>
        <value>0.00228133</value>
        <value>0.0104904</value>
        <value>-0.00227043</value>
        <value>0.999942</value>
    </param>
    <param name = "TranslationLeftRight">
        <value>-50.2541</value>
        <value>0.144023</value>
        <value>-0.153173</value>
    </param>
    <param name = "HasRGB">
        <value>1</value>
    </param>
    <param name = "ResolutionRGB">
        <value>1920</value>
        <value>1080</value>
    </param>
    <param name = "FocalLengthRGB">
        <value>1395.14</value>
        <value>1396.13</value>
    </param>
    <param name = "PrincipalPointRGB">
        <value>969.085</value>
        <value>552.345</value>
    </param>
    <param name = "DistortionRGB">
        <value>0</value>
        <value>0</value>
        <value>0</value>
        <value>0</value>
        <value>0</value>
    </param>
    <param name = "RotationLeftRGB">
        <value>0.999985</value>
        <value>0.00503999</value>
        <value>0.00220488</value>
        <value>-0.00503166</value>
        <value>0.99998</value>
        <value>-0.00376907</value>
        <value>-0.00222383</value>
        <value>0.00375792</value>
        <value>0.99999</value>
    </param>
    <param name = "TranslationLeftRGB">
        <value>15.0915</value>
        <value>-0.0578172</value>
        <value>-0.397592</value>
    </param>
</Config>

FocalLengthLeft, PrincipalPointLeft and DistortionLeft are different. Is my code wrong?

[MartyG-RealSense]

I recalled that the intrinsics coefficients are meant to be reported as all zero on the 400 Series cameras. The explanation for this is given in this discussion:

#1430

[LW-SCU]

Hi @MartyG-RealSense
Which parameter should I use？SDK2 or CustomRW tool.

[MartyG-RealSense]

My interpretation of the advice in the link would be that if the SDK sets the coefficients to zero because they are not used in the calculation of fx, fy, ppx and ppy then you should regard the coefficients as being zero too (i.e follow the SDK's way of doing things).

[robotlearning123]

When I rewrote different large parameters using CustomRW tool, the image was changed. See the results here:
IntelRealSense/realsense-ros#1723 (comment)

My interpretation of the advice in the link would be that if the SDK sets the coefficients to zero because they are not used in the calculation of fx, fy, ppx and ppy then you should regard the coefficients as being zero too (i.e follow the SDK's way of doing things).

According to here:
Intel RealSense D400 Series

• Left and right infrared images are rectified by default (Y16 format is not)
• The two infrared streams have identical intrinsics
• The two infrared streams have no distortion
• There is no rotation between left and right infrared images (identity matrix)
• There is translation on only one axis between left and right infrared images (translation[1] and translation[2] are zero)
• Therefore, the y component of pixel coordinates can be used interchangeably between these two streams

So it means the infrared images are rectified by default (or device?), and SDK does not rectify them again?
#1430 (comment)
@dorodnic

[MartyG-RealSense]

@wangcongrobot Y8 infrared is rectified. Y16 is not rectified as it is used for camera calibration.