Intel Realsense Depth Quality

[AKuma184]

I have been using the SR300 for quite some time.

Recently tested the D435 and the depth quality is not as good as the SR300

Is it a technology bottleneck or can we expect improvements in future firmware releases ?

[MartyG]

The D435 has a wider field of view than the SR300 and even the D415 camera model. However, as a consequence of the D435's particular hardware design, the D415 has better image quality and improved depth accuracy over distance.

For example, although the D415 and D435 may have comparable accuracy at close range, as distance increases, the depth accuracy of the D435 moves apart from the D415, becoming particularly noticeable after around 3 meters away. This link has a chart that illustrates estimated accuracy change over distance for the D415 and D435 models.

https://forums.intel.com/s/question/0D70P000005PV8fSAG

At very close range, the SR300 has better accuracy than even the D415. This is because although the 400 Series cameras can sense for a long distance, the trade-off of it being able to do this is in its very close range accuracy. This is due to the 'depth units' that the the 400 Series cameras use by default. The 400 Series cameras can though have their default depth unit scale changed to match the SR300's. This phenomenon is described in detail in the final comment at the bottom of the page of the discussion linked to below.

https://forums.intel.com/s/question/0D70P000006B2MfSAK

[AKuma184]

Is the 'depth units' paramter the only thing that prevents the D435 from performing as well as the SR300 ?

The minimum value that I can set using the software if 1/10 of a milimetre. That's 3 times less that an SR300.

I specifically want to use it for close range less than 2 metres.

The reason why I want to use the D series is its ability to see black objects that the SR300 cannot.

Any way I can set the the value to match that of the SR300.

[MartyG]

I was not able to reduce it to less than 1/10 either.

The SR300 and the 400 Series are not directly comparable technologically because the SR300 uses the 'coded light' method of projection, and the 400 Series uses the 'Stereo' projection method, based on a depth image generated from the left and right IR imagers.

As the information about the depth units said, you may also get improved close-range performance by using a lower resolution, such as 640x480.

The limitation with black or dark grey objects being hard for the camera to see should also apply to the 400 Series though. It is not a hardware limitation but a physics one affecting depth cameras in general, as dark grey / black colors absorb laser light. This is why objects such as a black cable can appear as an empty cable-shaped black area on images.

[AKuma184]

I am already working at the 640x480 resolution.

From observation I am able to see black patches on my objects through the D435 which wasn't visible through the SR300.

Still, I would love ways to tune it to produce a depth cloud as close as possible to the SR300

[MartyG · Accepted solution]

Intel has an excellent illustrated depth tuning guide document for the 400 Series that may provide additional useful insights for enhancing performance.

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

Improvements in image quality may also sometimes be achieved by turning off the auto-exposure function and setting your own exposure and gain values manually.