6 Replies Latest reply on Jun 29, 2018 10:12 AM by Intel Corporation

    Looking for clarity on depth perception

    ChicagoBob123

      According to this the sentence

      >> The default scale of a D400 device is one millimeter, allowing for a maximum expressive range of ~65 meters.

      Which makes sense at a range of 65535/1000 = ~ 65 meters but what does not make sense is the fact in the

      Realsense viewer you are defaulted to 4 meters or 12 feet.

      Then  you read

      The depth scale can be modified by calling rs2_set_option(...) with RS2_OPTION_DEPTH_UNITS, which specifies the number of micrometers per one increment of depth. 1000 would indicate millimeter scale, 10000 would indicate centimeter scale,

       

      Centimeter scale? If you increase the RS2_OPTION_DEPTH_UNITS to 10,000 you would be in centimeters per increment which would mean a depth range 650 meters.

      Help me here as that does not make any sense.

       

        • 1. Re: Looking for clarity on depth perception
          MartyG

          I wonder if it is related to depth of field.

           

          Depth of field - Wikipedia

          • 2. Re: Looking for clarity on depth perception
            ChicagoBob123

            The only way this makes sense is if the have it totally backwards.

            It defaults to 10,000 (millimeters mode) which gives you a range of ~6.5 meters and seems to

            match the 4 meter range meter on the viewer and you can lower it to 1000 (centimeter mode)

            which can deliver you 65 meters of range which is ~ 180 feet which would be GREAT if I

            make it work in the Realsense Viewer. 

            • 3. Re: Looking for clarity on depth perception
              Intel Corporation
              This message was posted on behalf of Intel Corporation

              Hello ChicagoBob123,

              Thank you for your interest in the Intel RealSense D400 Cameras.

              The depth units, whether it is .1 mm or 10 mm, does not change the effective range of the camera. It merely affects the units in which depth is reported. If you want a precision of 1 mm in your depth values, then you would not set your depth units to 10 mm.
              The 65535/depth_units calculation only gives you the mathematical, theoretical limit but the cameras effective range is still dictated by physics and the environment.
              The color gauge on the side of the depth view in the RealSense Viewer is used only for color visualization. It is not the actual range of the camera.
              Do not change the depth units while the depth camera is streaming.

              Thank you,
              Eliza

              • 4. Re: Looking for clarity on depth perception
                ChicagoBob123

                Thanks for the reply.

                Is there any place in the documentation that shows the realsense viewer interface and what all the options do or are for?

                That would be pretty helpful in understanding the SDK as well as what capabilities the camera has

                even though some of the options are clearly marked.

                 

                >>The depth units, whether it is .1 mm or 10 mm, does not change the effective range of the camera.

                But doesn't it effect the actual return values for distance since you are using 16 bits or 65535?

                Your Z16 format? So even if it doesn't limit the range of the camera it alters what it considers

                its maximum measured distance.

                 

                >>If you want a precision of 1 mm in your depth values

                No I have no use for this. I am not working on a scanner. 

                 

                >> the cameras effective range is still dictated by physics and the environment.

                This is true of any camera. The camera itself has a pixel density and I am sure the delta tween pixels

                become unusable at a certain point in the distance because of the resolution of the camera. 

                 

                >> Do not change the depth units while the depth camera is streaming.

                Found this out the hard way. 

                • 5. Re: Looking for clarity on depth perception
                  Intel Corporation
                  This message was posted on behalf of Intel Corporation

                  Hello ChicagoBob123.

                  You can find more information regarding RealSense Viewer on this user guide : 

                  https://www.intel.com/content/dam/support/us/en/documents/emerging-technologies/intel-realsense-technology/Intel-RealSense-Viewer-User-Guide.pdf

                  And regarding your second question, you are right. The mathematical limit is (0-65535)*depth_units. If you have a depth unit of .01 m, the largest depth value would be 655.35 meters. But unfortunately the camera is not capable of reading depth at this distance.

                  Regards,
                  Eliza
                  • 6. Re: Looking for clarity on depth perception
                    Intel Corporation
                    This message was posted on behalf of Intel Corporation

                    Hello ChicagoBob123,

                    Could you please let me know if I can help you with any other information?

                    Thank you,
                    Eliza