Depth image truncation near one edge on D400 series

[FGust3]

Hi,

I notice that depth data is always missing near one of the short edges of both the D415 and the D435 cameras, a "dead" region. I suspect this is some kind of stereo imaging artefact. In particular when imaging close objects, the extent of the dead region can be quite large, up to 10 % of the long image axis which in case of 1280 x 720 resolution corresponds to 128 pixels . I attach an image of a roof 60 cm from the D415 camera to illustrate the issue. I would have expected the full depth image to be usable apart from perhaps 4-5 pixel rows closest to the edges, but over 100? I would like to know if this is expected performance and if you plan to improve it? Thanks.

[MartyG]

I did some tests in the RealSense Viewer wirth my D415. I experienced similar image loss at the same edge, though not to the extent that you did. I found that I could get more depth detail at the edge if I unticked 'Enable auto exposure'.

[FGust3]

Thanks Marty,

I tried deactivating auto exposure and there is an effect but minor, 1-3 pixel rows, compared to the total width of the dead region. I tried updating to the latest firmware but no change. The D400 models we have are engineering samples, is it possible that the production cameras will be any different with respect to this? It is a rather serious loss of data.

[MartyG]

My D415 is an engineering sample one too. My experience from user feedback so far has been that image quality on the D415 has been good, with people preferring it to the D435.

[FGust3]

Image quality is one thing, missing data is another. I had a look on a few videos on Youtube where people are exploring the D400 cameras. Obvioulsy I'm not alone, this looks to be a general issue. The user below (https://www.youtube.com/watch?v=iY8ggcmcxqo Intel RealSense D435 vs D415 - YouTube ) for instance tests both a D435 (left) and a D415 (right) camera. Also here we can see a large region of missing data at the left edge of both camera images and the effect grows when objects are getting closer (but still far from too close). The result for the D415 agrees well with my observations, that only about 90 % of the sensor area is usable for depth sensing at distance ~ 60 cm. The D435 performs better in this aspect. I think most users were counting on using the whole sensor area for depth imaging. My question remains, will it be possible?

[MartyG]

This is probably a subject that the RealSense developer team could address better than I can. Having said that, during my earlier tests with the D415, I observed that the edge data wasn't impossible for the camera to perceive, but rather obscured by the settings. Turning off auto-exposure and manually changing the Exposure and Gain sliders in the controls of the RealSense Viewer allowed black-area detail at the edge of the image to come into view.