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Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Tue Jul 09, 2019 8:27 am
by qschebdrap
Here is the problem statement: there will be at most one AprilTag in view at all times and I need to find its approximate horizontal position in frame. The approximate size in frame of the tag might be useful but is not necessary. I don't need the tag ID, its pose, or any other information.

I have tried the find_apriltags function and it can get the job done, but the distance the tag can be seen from is pretty limited unsurprisingly. I'm wondering if there is a way to modify the algorithm or create a new one to only detect a tag rather than read it, and hopefully bump up the range a bit. I'm thinking of using something like a blob finding algorithm to locate the tag most of the time since the background should be somewhat regular. What sort of algorithm is recommended for this purpose? I've done some testing and the best I've done so far is comparable range to find_apriltags_w_lens_zoom.py, though the current background is more chaotic than the intended background.

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Tue Jul 09, 2019 2:26 pm
by iabdalkader

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Tue Jul 09, 2019 2:45 pm
by kwagyeman
There's an example script which shows off how to us find_blobs() to do what you want at 640x480. it's under the AprilTag examples.

We will have a DRAM camera coming out soon which will have no limits on this.

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Tue Jul 09, 2019 2:58 pm
by qschebdrap
I am thinking about the telephoto lenses, yes. I'm going to order them soon. I'm just worried that the smaller FOV might get in the way of other aspects of the project so I'm looking at other solutions too.

I did also test the blob AprilTag example but with the current chaotic setting its performance wasn't any better and it ran less than half the framerate. I'll test it out in the better environment too when I get a chance and hopefully it will do better.

When you say the DRAM camera is coming out soon, how soon? The project I'm working on will be at the point of no return in a couple weeks, but if the camera comes out in the next week or so I would gladly get one and try it out.

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Tue Jul 09, 2019 3:58 pm
by kwagyeman
Um, I just have dev units. If I get one working I could send it to you. Don't expect this to happen in a timely manner however.

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Tue Jul 09, 2019 4:13 pm
by qschebdrap
Oh, if they're dev units they'd be better used by someone else so no worries. The H7 was a lucky enough find for us and I don't think we could do our project in the time we have without it. Thanks for doing the work so we don't have to!

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Fri Jul 12, 2019 7:51 am
by ecdm2
Is this a DRAM camera like this:

https://hackaday.com/2014/04/05/taking- ... dram-chip/

Or is a DRAM module between the camera sensor and the mcu ?

If it is between the sensor and the mcu will it slot between either the rolling or global shutter modules or is it on a board with its own sensor ?

Best Wishes

Ed

Re: Minimal detect AprilTag (don't need tag ID) with better range?

Posted: Sat Jul 13, 2019 3:44 pm
by iabdalkader
ecdm2 wrote:
Fri Jul 12, 2019 7:51 am
Is this a DRAM camera like this:

https://hackaday.com/2014/04/05/taking- ... dram-chip/

Or is a DRAM module between the camera sensor and the mcu ?

If it is between the sensor and the mcu will it slot between either the rolling or global shutter modules or is it on a board with its own sensor ?

Best Wishes

Ed
It's a new camera with SDRAM for the MCU.