Is there any document described the minimum observable depth(min-Z) of D415?

[yyosh4]

Hi, 

Now, I'm examining functions of D415, especially its depth range and accuracy using with the official Depth Quality Tool.

And, I noticed minimum observable depth(min-Z) of the sensor varies when I changed the resolusion of depth image.

For example, when I set the resolution of depth image to 1280x720, min-Z is strictly 40cm (in my impression).

But, when I set the resolution of depth image to 420x242, the min-Z is 20cm(But it seems not strictly

because the depth value have very fluctuated. So, I didn't check the actual minimum observable value)

After encountered above issue, I read a specification documents and datasheets of the sensor.

And I confirmed some documents is denoted the min-Z of the sensor.

For example,  In the below document (pp.56), in the case of "resolution:1280x720",  min-Z is 450[mm].

But this result is not corresponded with results I saw.

If you have any ideas about this issue, Could you tell me some advices?

https://www.mouser.jp/pdfdocs/Intel-RealSense-D400-Series-Datasheet_003.pdf

[MartyG · Accepted solution]

Your observation about changes in MinZ with resolution are correct. When the resolution is lowered, MinZ reduces, meaning that the camera can get closer to an object. When the camera is close enough that it goes below the current MinZ then the image starts to break up.

A more precise way to control MinZ is with the 'Disparity Shift' setting. As the value of Disparity Shift is increased, the MinZ reduces but the maximum distance (MaxZ) also reduces. you can read about MinZ, Disparity Shift configuration and much more in Intel's excellent illustrated camera tuning guide.

Extract images from the guide on the subjects of MinZ and Disparity Shift are shown below - please left-click on them to view them in full size.

https://realsense.intel.com/wp-content/uploads/sites/63/BKM-For-Tuning-D435-and-D415-Cameras-Webinar_Rev3.pdf?language=en_US