14 Replies Latest reply on Feb 18, 2018 2:43 PM by BjarneG

    Multiple D400 RealSense simultaneosly

    marfix

      Hi everyone,

       

      I wonder if it's possible to connect and use multiple D400 RealSense cameras using one PC. Since those sensors are using infrared projector, I would like to know if they produce interference when are facing eachother. Moreover, since the cameras use USB 3.0, can they all be plugged into one PC or is it necessary to have individual USB controlers per camera?

       

      Thank you very much

        • 1. Re: Multiple D400 RealSense simultaneosly
          MartyG

          The RealSense SDK 2.0 software that the 400 Series cameras use come with a sample program called 'Multicam' for displaying inputs from multiple cameras in a series of 'viewport' panels.  I would therefore infer from this that multiple 400 Series cameras can be streamed on the same PC, otherwise the sample program would need a way to connect to other PCs that have a camera attached.

           

          In the Multicam sample, two cameras point at different locations.  This implies that interference when camera projections cross over each other's paths may still be an issue.

           

          Some years ago, Microsoft released some research on the original Kinect camera that suggested that interference patterns could be broken up by vibrating the camera with a motor.

           

          Using Vibration Motors with Microsoft Kinect | Precision Microdrives

           

          Kinect 1 used structured light / coded light as its scanning mechanism, whilst Kinect 2 used a different scanning method called time of flight.  The RealSense SR300 is a structured / coded light device, whilst the 400 Series cameras are based on stereo imaging though, so the Microsoft technique may not work on them.

          • 2. Re: Multiple D400 RealSense simultaneosly
            SMM77

            Hi Marty,

             

            I'm still confused about IR interference from multiple cameras, quoting you from this and another conversation, I feel that these responses are inconclusive:

            >> "the 400 Series cameras are based on stereo imaging"

            >> "There may be interference if the IR from one sensor is directly pointed at another sensor. The sensors should be pointed toward an object or scene where the sensors do not point at each other."

             

            Please allow me to restate the question:

             

            a) Ignoring the corner case where two cameras are pointed directly at one another such that they're shining IR into one another,

             

            b) Will the D-series cameras have the same characteristic as the ZR300 series cameras regarding IR interference? Quoting P18 of the ZR300 Data Sheet:

             

            >> "4.3 Infrared Projector Interference In general, the ZR300 is not subject to infrared projector interference from multiple cameras in use simultaneously."

             

            * Noting that no such paragraph exists in the D400 series Data Sheet.

             

            c) To explicitly state a practical problem: At a focal distance of 6ft, if two D400 series cameras, spaced 3ft apart, were aimed such that their image centers were focused at the same point on a stationary reference object -- would the sensors interfere?

             

            As a simple diagram, where "O" is a reference object and "A" and "B" are D400 series cameras:

             

                     O

                    /   \

                   /     \

                 A       B

             

            ^^ In the above diagram, do IR patterns from A & B interfere where they intersect on object O?

             

            Thank you ahead of time for specific detail.

             

            -S.

            • 3. Re: Multiple D400 RealSense simultaneosly
              MartyG

              I do not have any further information to offer on the subject of interference, sadly.  I have not heard of solutions for non ZR300 cameras other than the Microsoft vibration one or rotating cameras like a lighthouse so windows of opportunity for the lasers to not overlap open up.  I believe the ZR300 anti interference tech was unique to that model.

              • 4. Re: Multiple D400 RealSense simultaneosly
                SMM77

                Thanks, Marty. I was probably under the incorrect assumption that you worked for Intel and had specific access to such info.

                 

                I'll repost my question to the broader group. Thanks for all your helpful insights!

                • 5. Re: Multiple D400 RealSense simultaneosly
                  MartyG

                  Yes, I don't work for Intel.  An Intel support agent could inquire to the RealSense engineering team.  I feel though that if there was a solution, Intel would already be promoting it in the same way they did with the ZR300's interference tech.  It is notable that in SDK 2.0's Multicam example, the cameras are pointed at different locations.

                   

                  Good luck!

                  • 7. Re: Multiple D400 RealSense simultaneosly
                    Intel Corporation
                    This message was posted on behalf of Intel Corporation

                    Hello SMM77,

                    Like the ZR300, in general, the D400 series cameras are not subject to infrared interference from multiple cameras in use simultaneously. You may see some interference if the IR projection from one camera goes directly into the IR sensor of another camera. If interference is observed for any reason you can lower the exposure setting and it should improve the situation.

                    Regards,
                    Jesus G.
                    Intel Customer Support

                    1 of 1 people found this helpful
                    • 8. Re: Multiple D400 RealSense simultaneosly
                      MartyG

                      Thanks for the useful advice about lowering the exposure to reduce interference, Jesus.  Many users who want to use multiple cameras want to put them close together in a way where the lasers end up overlapping their paths and causing interference.  Hence all the effort put into thinking of novel ways to minimize those interactions.    I'll pass on your exposure advice. 

                      • 9. Re: Multiple D400 RealSense simultaneosly
                        SMM77

                        Thank you for clearing this up, Jesus.

                        • 10. Re: Multiple D400 RealSense simultaneosly
                          BjarneG

                          Very useful info, @Jesus!

                           

                          By "reducing exposure setting" do you mean setting a lower value in the slider "Controls / Exposure" or do you mean disabling auto-exposure and specifying a ROI?

                           

                          Regards,

                          - Bjarne

                          • 11. Re: Multiple D400 RealSense simultaneosly
                            Intel Corporation
                            This message was posted on behalf of Intel Corporation

                            Hello BjarneG,

                            I mean lowering the value in the slider "Controls/Exposure."

                            Regards,
                            Jesus G.
                            Intel Customer Support

                            • 12. Re: Multiple D400 RealSense simultaneosly
                              BjarneG

                              Thanks for clarifying  @Jesus.

                               

                              Could you perhaps briefly outline the purpose of the ROI-setting? Is this related to the mentioned exposure-value?

                               

                              Regards,

                              - Bjarne

                              • 13. Re: Multiple D400 RealSense simultaneosly
                                Intel Corporation
                                This message was posted on behalf of Intel Corporation

                                Hello BjarneG,

                                Page 68 of the datasheet for the D400 explains that the ROI is the Region of Interest where Auto Exposure will be performed. You may also play with Gain if interference is observed.

                                Regards,
                                Jesus G.
                                Intel Customer Support

                                • 14. Re: Multiple D400 RealSense simultaneosly
                                  BjarneG

                                  Thanks, Jesus.

                                   

                                  Regards,

                                  - Bjarne