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Gorbag
11-23-2009, 07:00 PM
So I see at Robotis they are now selling the wireless camera set separately from the expert kit, but only "thru their distributors". Will that include Trossen? To be honest, the most interesting part for me would be the expert CD since I'm hoping there are some sources to the firmware on there that allows one to safely charge the battery. But I won't throw the camera away :wink:

http://www.robotis-shop-en.com/shop/step1.php?number=679

Camera-wise I'm thinking the surveyor blackfin is going to be more interesting. But I'm still trying to find appropriate vision software for Linux (esp. openembedded, but ubuntu in a pinch) that gets beyond the usual blob grouping.

Adrenalynn
11-23-2009, 07:40 PM
You don't want to get within ten miles of that POS 2.4Ghz camera. But if you insist, I'll do you a MUCH better deal than that!

Of course, you'll just end-up returning it, and I'll eat shipping. Never mind.

The Blackfin camera is WiFi. Stick with that if you have that kinda money burning a hole in your pocket.

As far as vision software goes, you can code whatever you want, sky's the limit, against OpenCV.

DresnerRobotics
11-23-2009, 10:32 PM
We will not be stocking this camera. If you have your heart set on it, we could arrange a special order with the next Robotis shipment we receive. That said, 'Lynn here offers very sound advice ;)

Gorbag
11-24-2009, 07:51 AM
@Adrenalynn: OpenCV - cool; I hadn't run across a pointer to that library before. Thanks! I've been looking at Lowe's SIFT algorithm (http://people.cs.ubc.ca/~lowe/keypoints/) (binary only windows, linux). But to get it to run under OE I have to reimplement it from the published papers. OpenCV may make that easier!

@Tyberius: No worries. I like the blackfin much better; I only considered the Robotis camera for the software out of the expert kit. I'm not using the CM-5 much anyway so it's not worth the cost to me if the camera is really valueless.

Adrenalynn
11-24-2009, 05:52 PM
NP - OpenCV is _the_ defacto-standard. It's slow, but it's rather very complete. And because it's such a standard, you'll findn umpteen examples on the Intarwebz, but also a good many complete book treatments if you search Amazon.

Pi Robot
11-28-2009, 08:45 PM
The Blackfin camera is WiFi. Stick with that if you have that kinda money burning a hole in your pocket.



I've been considering the Blackfin with WiFi option for some time now. Can anyone here report what you have seen for frame rates at different resolutions over 802.11g? Say 160x128, 320x240 and 640x512? Also, how reliable has the connection been and up to what range (approximately)? Does the camera have auto-exposure capabilities that can be turned on and off? And finally(!) has anyone tried the 120 degree lens? I find the narrow FOV of most WiFi webcams to be a significant handicap when my robot is trying to track moving objects (using RoboRealm).

Thanks!
patrick

Adrenalynn
11-28-2009, 09:01 PM
>> I find the narrow FOV of most WiFi webcams to be a significant handicap when my robot is trying to track moving objects (using RoboRealm)

Remember - the wider the lens, the fewer the number of pixels said moving object occupies - and therefore the harder it is to track them.

Pi Robot
11-28-2009, 09:34 PM
Remember - the wider the lens, the fewer the number of pixels said moving object occupies - and therefore the harder it is to track them.

Good point! The trouble I have with the narrower FOV cameras is that a moving object can easily move out of the FOV before a tracking algorithm has time to catch up, especially if the frame rate is not very high.

--patrick

Adrenalynn
11-28-2009, 10:01 PM
A typical lens/sensor on a webcam should see between 8'x6' @ 10ft and 6'x4.5' at 10ft.

At even 15fps, it would need to be moving something along the lines of 60+ feet/sec not to at least get one frame. Around 41mph horizontally across the camera.

How fast you can process that video is typically the question that needs to be addressed. If you shrink the number of available pixels down, you're going to have to do a lot more processing to recognize the object, so you kinda get a catch-22.

That said - doing obstacle avoidance or looking for markers can be made a bunch easier with a wider lens, as long as the obstacles/markers are really large. Otherwise you pretty much are best suited with the stop-and-pan method, imho.

Pi Robot
11-29-2009, 09:06 AM
Great analysis! As it turns out, the object tracking I have done so far takes place much closer to the camera--more like 1-3 feet as shown in this video:

http://www.pirobot.org/videos/0006/ (http://www.pirobot.org/videos/0006/)

And if the object is already centered in the FOV, it can leave the FOV by moving just half of the width. Also, the object being tracked is usually something big and colorful so the object detection/recognition task is fairly easy. In practice, I found I had to use the fastest webcam I could find--the Philips SPC 1300NC at 90 fps--to get good tracking for quick object motion this close to camera.

--patrick

Adrenalynn
11-29-2009, 12:18 PM
Does it really get 90fps @ 1.3mpixel over USB2? Wow.

That has an 80deg advertised field of view. I'd imagine it starts to fish-eye at the edges. You don't want to go any wider than that or the error will kill ya.

I just noticed you're in Stanford. Here I almost liked you too. Go Bears! :tongue: ;)

Pi Robot
11-29-2009, 11:39 PM
Does it really get 90fps @ 1.3mpixel over USB2? Wow.

That has an 80deg advertised field of view. I'd imagine it starts to fish-eye at the edges. You don't want to go any wider than that or the error will kill ya.

I just noticed you're in Stanford. Here I almost liked you too. Go Bears! :tongue: ;)

Yeah, the wide FOV was another reason I like this camera. I think I measured it at around 75 degrees when I first got it and I can't see any fish-eye effects at the edges. You can really get 90 fps or at least mid-80's up to 320x240. At 640x480 you max out at 60 fps and anything higher is limited to 30 fps. This also assumes you have good lighting otherwise you have to decrease the shutter speed and lower the fps. I rarely run any higher than 320x240 since RoboRealm can slow to to a crawl with higher resolutions depending on the modules you are using.

Oh, and my alma mater is the University of Toronto, so, like Switzerland, I get to stay neutral on the Bears/Cardinal thing. :cool: