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Is my RealSense D435i broken? When I let the camera face white plane, it shows noisy points with different depths

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31 comments

  • MartyG

    When the image looks this broken, the first action that I would usually recommend trying is to re-calibrate the camera.  This can be done with the Custom Calibrator tool for the 400 Series cameras, which can be downloaded from the link below.

    https://downloadcenter.intel.com/download/28517/Intel-RealSense-D400-Series-Calibration-Tools-and-API 

    If you are using Linux, instructions for Linux installation of the calibrator tool can be found in the user guide for the tool:

    https://dev.intelrealsense.com/docs/intel-realsensetm-d400-series-calibration-tools-user-guide#section-3-1-installation-on-linux-ubuntu-16-04- 

    Before you do this though, may I confirm that you are not holding the camera too close to the white plane, please?  Your mention that the image improves when reducing the resolution makes me wonder if the distance that the camera is positioned at may be below the camera's minimum depth sensing distance.  When the camera gets close enough to a surface that it is below the minimum distance, the image progressively breaks up more and more as the camera gets closer to the surface being observed.  

    Reducing the resolution can reduce the camera's minimum sensing distance and allow the camera to get closer to objects before the image starts to break up.

    You could test this by checking if the image improves if you move the camera back further away from the white plane.

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  • Twinsnan

    I have tried distance from 0.2m to 4m. it performs the same. I find that there always be noisy points between the object and the camera. It seems that the noisy points have the same distance which don’t change with the distance of the object.

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  • MartyG

    Thank you very much for the information.  Does the image improve if you turn off the IR Emitter in the RealSense Viewer side-panel?  You can turn it off by left-clicking on the blue box next to 'Emitter Enabled' to turn the box black, which means that it is Off.

    The purpose of the IR Emitter is to project a semi-random pattern of dots onto the scene to help the camera analyze depth on flat, low texture surfaces such as walls and doors.  Reducing the laser power reduces the visibility of these dots.

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  • Twinsnan

    Hi MartyG. I have turned off the IR Emitter and it performs better than before.

     

    So what is the problem? What should I do?

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  • MartyG

    When the dot pattern projection is absent or has its visibility minimized, the camera can also read depth detail from surfaces using the ambient light in the scene.  Unlike most depth cameras, the 400 Series cameras can actually work better in strong light.  

    So if you have good light in the location where you are using the camera and this is giving you good-quality image results then you may not need to have the IR Emitter enabled.

    If a camera is used in a location with strong light or low light conditions, having the IR Emitter component enabled as well may saturate the IR sensor with light.

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  • Twinsnan

    I use the camera indoor not outdoor. there is only normal lamp light here.

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  • MartyG

    What kind of results do you get please if you have the IR Emitter enabled and disable Auto-Exposure?

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  • Twinsnan

     

    Just the same.

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  • MartyG

    There certainly seems to be a clear relationship between the IR dot pattern and your image problems.

    1.  You reduced the Laser Power setting first (which reduces the visibility of the dot pattern) and the image quality improved a bit.

    2.  You turned off the IR Emitter completely and the image improved a lot.

    If you can achieve good results without the IR Emitter enabled then I would recommend continuing with that and letting the camera use the room's ambient light to analyze the depth detail. 

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  • Twinsnan

    Does the laser speckle look like this below?

     

    Actually I won't ask about this problem if it can work well just adjusting some params. It works not as good as excepted when I compare it's performance with other D435i cameras' online.

    Even I close the IR emitter, The noisy points exist on the horizontal plane.

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  • MartyG

    Apologies for the delay in responding further, I was very carefully considering your case.

    I noticed on your color image that the IR emitter pattern seems to be leaking through to the color image.  This should not be happening, as the visibility of the dot pattern should be limited to the IR image.  I have seen a few previous cases where this has happened, and a solution was to reduce the Laser Power like you did.  Here is an example case of this phenomenon:

    https://github.com/IntelRealSense/librealsense/issues/4098 

    The dots on the horizontal plane are likely not related to the IR emitter, especially if it is turned off.  Noise on the horizontal floor plane can be caused by a separate issue.  Could you try selecting the 'High Density' custom preset option in the preset menu drop-down near the top of the Viewer's options panel please (the one that is normally set to 'Custom' by default) and see if that improves the floor please?

    The Chief Technical Officer (CTO) of the RealSense Group at Intel (agrunnet) gives advice in the link below about achieving further improvement after turning the IR Emitter off.  

    https://github.com/IntelRealSense/librealsense/issues/4703#issuecomment-523947286 

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  • Twinsnan

    I tried, but the viewer gives me a error log

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  • MartyG

    A few other people have encountered this error when switching modes that are related to the Advanced Mode of the camera, such as the visual presets.  An example here is a Raspbian Buster user with a Raspberry Pi 4.

    https://github.com/IntelRealSense/librealsense/issues/4799 

    Looking at the floor part of your image, it picks up the toy on the floor but not the floor itself, suggesting that it cannot read the floor.  Do you get better floor detection results if you tilt the camera up so that it is more flat horizontal instead of pointing downward?

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  • Twinsnan

    emmm... I tried other other kind of vertical plane like carton. The result is normal that the camera can recognize the floor if I turn off the Emitter(nosiy points when turn on as before). Maybe it is related to the mateirals of vertical plane???

    It can not recognize the floor when I tilt the camera up. It can not recognize the floor when I put other things under the toy.

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  • MartyG

    Thank you for your patience.  Does the floor image improve if you turn on every Post Processing filter at the same time, like in this image:

    https://www.calvert.ch/wp-content/uploads/2018/06/officedepth.png 

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  • Twinsnan

    Another Problem is that the infrared streams of the two infrared cameras will shake suddenly every few seconds periodly

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  • MartyG

    Regarding the IR shake: does the indoor room that the camera is in have fluorescent lights such as ceiling strip lights instead of lights with bulbs, please?

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  • Twinsnan

    Without Hole Filling. no Emitter

    With Hole Filling. no Emitter

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  • Twinsnan

    I think they are all LED lamps?? I am not sure.

    I notice the two infrared steams exchange the frame to another suddenly.

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  • MartyG

    LED lights should be the best type of lights to use - better than ordinary bulb lights - because they do not cast shadows on the scene.  That is why LED lights are used in professional photography.

    I just noticed that your ASIC and projector temperatures are abnormally high.  I would expect an ASIC temperature of around 29-30 during normal use if the camera has not been running for long.  The recommended maximum operating temperature of the 400 Series camera is 35.  Exceeding the recommended temperature can cause problems.  Do you know what might be causing the camera to get this hot, please?

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  • Twinsnan

    I dont know. I notice it had been hot like this since I got the camera..I just connect it on my linux desktop and the temperature is 23 degree outside

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  • MartyG

    It is definitely a highly abnormal temperature for those conditions.  One effect of excessive temperature could be the disruption of the camera's calibration, requiring a re-calibration of the camera to get a good image.

    A possible cause of a device that is attached to a USB port rapidly overheating can be a fault in the USB port.  Does the camera casing feel very hot to the touch?

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  • Twinsnan

    Yes, it is hot when i touch it. Do you mean the USB on desktop or the USB on the camera?

    My RealSense SR305 is not hot when I use it 

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  • MartyG

    It would be the USB port at the computer end, not the camera's port.

    If other USB devices such as the SR305 are not rapidly heating up, that may indicate that the port is okay and it is an issue specific to the D435i camera.

    I recall a case where a user's camera was being overheated and they were getting incomplete or corrupted frames when their ASIC temperature was 60 and their projector temperature 56.  They found that the cause was that the industrial single-board computer that they were using was overheating.   

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  • MartyG

    I just recalled that a faulty USB cable can also cause the rapid overheating problem with USB devices.  Since the D435i and SR305 use different cable types, this may be why the SR305 does not experience a high temperature with its own cable.

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  • Twinsnan

    I will test my RealSense cemeras later on different desktops and laptops. What do you mean about the "rapidly heating up"? In how much time would it be supposed to be rapid? 

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  • MartyG

    From the reports I have seen on the internet about rapid heating of USB devices (not just RealSense), I would expect the casing to become hot within the first few minutes of operation.

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  • Twinsnan

    I test the D435i on my laptop. the ASIC temperatures get 45-47 as well. I dont know the SR305's temperature because there isn't temperature indicator on the viewer. But I think it is lower than D435i when i touch it. (I have to say the temperatuer is highter than 29-30, maybe35-40?)

    So what should I do next?

     

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  • MartyG

    Are you able to try the D435i with a different USB-C cable please to eliminate the possibility that the heating is caused by the USB cable?

    If you are getting the same results on different machines, the possibility should be considered that it is a hardware fault with the camera.  If so, you should be able to return the camera for a replacement or refund if it is within its warranty period.  If you bought it from Intel's online store then it would be returned to Intel.  Otherwise, it should be returned to the retailer that it was purchased from.

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  • Twinsnan

    I replace it with a shorter cable And the temperature is high as before. 

    How could I prove my camera is broken?(Because it can work , even though the depth data is incorrect)

    How about the return process If I bought it from retailer?

    Thanks!

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