lens distortion

[AAlex44]

Hello,

My SR300 IR/Depth sensor is capturing images with obvious lens distortion, is the sensor supposed to provide an undistorted capture image or should I implement the code to do a lens correction to the image?

If it is the case, is there any C# SDK API (or sample) to correct the distortion via PXCMCalibration.StreamCalibration parameters?

Thank in advance.

[idata]

Hi Alex@32,

Thank you for contacting us.We'd like to help you with this so you can continue to work with the SR300.We've used the SR300 in several scenarios and have never seen the obvious distortion you mention. Would you please post a picture that shows this distortion? Also, could you let us know how you're capturing the images and name the example you're using. We'd like to try and reproduce this behavior. Please mention the DCM and SDK version you're using.We'll be waiting for your response.Regards,-Sergio A

[AAlex44]

Hello Sergio,

Thank you for your prompt reply, and your support!

The DCM version We are using is 3.3.27.5718 and the SDK 11.0.27.1384.

The scanning target is a flat table where we put some rectangle blocks (Z distance ~1meter), and we would like to work on the Depth Images only.

I put below a screenshot of the depth stream, display by from CameraExplorer SDK sample, where we can observe

the XY distortion (barrel type).

The depth sample image, we get from NewSample delegate in the test application, is similar:

Now, if we look at the Z positions, we also have a distorsion:

Do I have to calibrate and correct this distortion in a separate module, or is such of distortion is managed by the SDK API?

Regards,

Alex

[idata]

Hi Alex,

We tested the Depth Stream example and the distortion we observed was almost imperceptible. We looked at the SDK R3 documentation for calibration settings that could be changed. The closest thing we could find was described in here https://software.intel.com/sites/landingpage/realsense/camera-sdk/v2016r3/documentation/html/streamcalibration_pxccalibration.html?zoom_highlightsub=distortion https://software.intel.com/sites/landingpage/realsense/camera-sdk/v2016r3/documentation/html/streamcalibration_pxccalibration.html?zoom_highlightsub=distortion . I haven't tested these calibration functions, but, they may be able to provide some insight.Let us know your results.-Sergio A

[MartyG]

I remember in an Intel article on RealSense scanning that they recommended that when you place your object on the flat table, you should position the object so it fills the camera's view to get best results.

[AAlex44]

Hi guys,

Thank you for your advices! I'll make more tests of positionning, and implement a distortion correction using the Stream calibration parameters.

I'll keep you posted.

Regards,

Alex

[idata]

Hi Alex,

Do you have any updates for this case? Let us know the results of your tests.-Sergio A

[MartyG]

RealSense expert Samontab reported in 2014 that his F200 camera (which is the direct predecessor of the SR300) seemed to have a "barrel" distortion. Does this sound like what you are seeing with your camera?

https://software.intel.com/en-us/forums/realsense/topic/536648 Barrel distortion and internal camera parameters of the IR camera

Barrel distortion is a curving of an image where it looks like the image has been bent around the surface of a sphere.