Depth sensing irregularities - Astra Pro

Technical Support & Q&A
1

I am running the Astra Pro on Mac OS X both with an existing openNI install and the SDK version. I am running side-by-side comparisons with the Structure Sensor.

I have noticed that the Astra has significant trouble reading depth in the centre of the image in certain situations where the Structure Sensor has no problems (reporting zeros). I have also noticed that there is significantly more zero noise (inconsistent, flickering unresolved distance (reporting zero).

There may be some filtering or noise reduction built in to the Structure Sensor that is masking some of the noise in its signal, but the substantial difference in unresolved distance areas is unexpected.

The Astra Pro also exhibits significant tearing in the lower 1/2 of the depth image in various somewhat predictable contexts. (could be a frame sync issue?) It appears as I tilt and pan the sensor around the room. At certain angles (probably when looking at certain features in the scene) the tearing appears, and moves up and down the frame as I tilt back and forth.

Is it possible that I have a defective Astra Pro? Or are these known issues that have workarounds.

Thanks!

David Rokeby

2

Could you post a picture or two of the Astra Pro depth image with the issues you’re describing?

3

Hi Josh,

I tried sending images a few times over e-mail without success. Hopefully I will be able to embed them here.

Issues:
tearing of the depth image:
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unresolved distances in the centre of the image (varying distances)
I compared my structure sensor output using the same code (DepthViewer and my own code)
In all cases, I see significant areas that the Astra Pro cannot read (returning 0) but where the structure sensor has no problem. The Astra Pro issue lessens towards the edges of the image for some reason.

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4

Hi Josh,

I have been trying to upload images showing the problem, but the web-page gets stuck at “Uploading”.

Any suggestions? (Using Safari)

Can I send them to you over e-mail in some way or upload them to drop box for you?

I have tried various things with no success so far.

David

5

David,

Please email info@orbbec3d.com. You can attach the images, or include dropbox links, and please include a link to this thread. One of our support techs will reply.

6

Hi Josh,

I will upload the images as you suggest.

In the meantime, in further testing:

I am pointing the Astra Pro straight down towards the ground from about 13 feet in the air. The distance to the floor registers as though the floor is at a 10 degree angle. (i.e. I get a progressive increase in distance across the horizontal axis of the frame.)

I am assuming this is not standard behaviour… Could this be some error in calibration in this unit or a mispositioned structured light projector?

7

Hey,

could the issue be assigned to a normal behaviour or an error in the sensor?

Best
Peter