Depth Extraction

[Dan van Kley]

Just started using your program and have been enjoying it. Well done, and thanks for putting in the time.

I'm having some trouble getting the depth extraction to work the way I want it to in Intrael. Either I'm doing something wrong, or I need to change my expectations. My understanding from the latest docs is that a value of e=0 does no background extraction (intrael detects anything between z and Z as an object), and both e > 0 and e < 0 generate a reference frame (whatever Intrael sees as present in the viewing area when it builds the frame) and both do different things with it. My desired functionality is pointing the kinect at a given room, running background extraction, and then having Intrael only report objects that are closer to the kinect than the background reference frame (displaying them as white/gray and including them in the blob detection), while ignoring the background reference frame entirely (displaying as black and being excluded from blob detection).

What I'm seeing is that e > 0 extraction seems to recognize the background, but still display it as present (white/gray) and detect it as an object blob and display any objects that move between it and the kinect as an absence of space (black). This causes the background to be one big object blob split by anything that moves between it an the kinect. This is exactly the inverse of what I want.

I expected e < 0 extraction to do the opposite of e > 0 extraction, and assumed it's what I want. However, when I try to use it, I only see alternating gray and black vertical bars and no video or object detection. Should e < 0 do what I'm looking for? If so, what do I need to change to make it work properly?

I'm running an AMD x86 processor on Ubuntu 14.10 with the latest code and dependencies (as of last week). According to the Ubuntu system monitor, the program is not resource locked in any way.

Any help or advice would be appreciated. Thanks!

[Γιάννης Γράβεζας]

That was a bad bug. I've just fixed it in the svn, please try it out. Indeed the e > 0 is what you're looking after. e < 0 will be deprecated in the near future. It was meant for touchscreen setups but is not really useful afterall.

Thanks for your kind words. The software hasn't been updated lately as I'm working on a complete overhaul that will bring websockets, binary data packing and improved latency & performance. If you're using the js lib you won't need to change anything in your blob handling code. The background removal functionality does change a bit but it's worth it as it adds alot more versatility. The client app will be able to send the server the reference frame for background removal( which allows for lots of neat tricks ). I'm very close to releasing it, maybe even by the end of the week. I can notify you if you like. 

Kind regards,

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Yannis Gravezas

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[Γιάννης Γράβεζας]

oops you also need to provide -r <n> on the command line now. This sets the number of frames to use for building the reference frame for background removal 

[Dan van Kley]

Thanks for the amazingly fast and thorough response. You can't buy service like this :)

I will update and rebuild after work today and give it a shot; thanks very much for the fix. The new version sounds fantastic and I look forward to seeing it. Please let me know when it's released and I will definitely take a look.

Thanks again!

[Dan van Kley]

Just rebuilt and tried again (with -r on the command line, as you said) and it works great now. Thanks for the incredible response time! Looking forward to the next release.

[Γιάννης Γράβεζας]

Thanks for the report. As a side note, if you don't need the rgb stream you can disable it by passing a -n(without argument) on the command line. This will improve latency and performance(but you probably don't need it on intel systems). Do you mind if I ask what type of application you're working on? If you need anything more functionality wise, please suggest. Cheers

[Dan van Kley]

Good to know, but for my application I want to have the RGB stream available for my users. I basically have a dedicated server for this thing, so hopefully performance won't be an issue.

I'm just getting into machine vision stuff, so my first application is pretty basic. My office plays a lot of table tennis and we needed a better way to tell if the room was occupied, who was playing, how long they were playing, etc. This could probably be done with a motion sensor or web cam, but I had a Kinect available and figured this would be way more interesting and we could add more advanced features later. Not a terribly interesting application, but you have to start somewhere :)

[Γιάννης Γράβεζας]

Every application that fills a purpose has its merit. Most people that use intrael setup touchscreens with it so it's refreshing that someone does something different(And it uncovers bugs as well). Performance won't be an issue, I would just suggest to setup the dedicated server on linux as windows sometimes loses the connection with the kinect. This is a hardware fault which gets corrected automatically on linux but not on windows(yet). Anyways back to work, have fun with coding the thing