FPS is far higher when used during daylight with lots of ambient light than at night in the dark

[GoogleCodeExporter]

What steps will reproduce the problem?
1.  Load up ltr_gui
2.  Either on Camera View or 3D view click start
3.  Open curtains, let daylight in, note fps
4.  Wait until dark, turn off lights, and follow steps 1 and 2, note fps

What is the expected output? What do you see instead?
fps should be the same.  I get better fps during daytime than at night

What version of the product are you using? On what operating system?
0.99.12 on Linux Mint 17

Please provide any additional information below.

I'm admittedly a crappy £10 polaroid webcam I bought from Asda which I ripped 
the IR filter out of.  Using it in NP Trackclip Pro mode with my home built 
head tracker.  During daylight hours I get a constant 25-30 fps but at night I 
only get about 10-15fps.  THe brighter the room is, the better the fps I seem 
to get.  I'll also note that I have a Microsoft lifecam VX-800 that I was using 
on face recognition mode and I noted the same issue on that.

In the Device Setup tab I've got the Threshold slider all the way up at about 
the 210 mark and I've got a visible light filter on the camera lense so it only 
picks up infrared.

Original issue reported on code.google.com by ra...@staticmapper.com on 15 Feb 2015 at 7:14

[GoogleCodeExporter]

Hello,

the symptoms you describe suggest, that you have the autoexposure on. That way, 
the camera decides what exposure setting to use based on the average brightness 
of the frame; when it gets dark, it automatically lengthens the exposure, 
lowering the FPS.

Check in a software like guvcview, where you have the webcam controls available 
and see if you can turn the autoexposure off and then set the exposure manually 
to gain good FPS while having acceptable image (blobs bright enough to cross 
the threshold).
Unfortunately not every webcam exposes this setting...

Other than that, there is not much that Linuxtrack can do about it - it 
requests certain resolution/framerate, but the exposure settings overrides that.

Kind regards,

Michal

Original comment by f.jo...@email.cz on 16 Feb 2015 at 5:59