Stereo Vision for localization
c depalma from United States  [4 posts]
11 years
I plan to build an outdoor robot.  Want to use stereo vision for Localization using triangulation.    I plan to use landmarks on the edge of my property and triangulate on them.  

My thought is I will have to use a laptop on my robot.  I will be making my own stereo camera out of 2 webcams. and will use color based tracking and COG to get coordinates of tracked object from each camera.  

Question: Can RoboRealm handle 2 web cams?  What specs Mem, CPU, etc would I need to process the localization.  I don't expect the robot to move faster than 3 mph.  ( it is an old electric wheelchair )

Do you think webcams will function adequately outside in a 200 x 200 ft area?

Will I need framegrabber card?

Thanks in advance.
Anonymous 11 years
RoboRealm should be easily able to handle 2 webcams given that the CPU is ok in handling that amount of data from two cams. Memory is not normally an issue .. anything above 64M should be fine. The CPU is the issue ... faster and more cores is always better. I'd recommend getting the best you can for the amount that you can spend. This is simply from the fact that once you accomplish the simple things you'd want to move onto the more complex such as dense optical or stereo which will really require a high CPU and multi-core system.

Webcams outside can cause issues with streaking and color loss due to the sunlight. For example the images in


show one such issue. It will depend on what you're trying to accomplish and may require some experimentation with different cameras to see which one functions best. Some cameras are better than others with sunlight but may appear worse in quality indoors. If you can, collect a couple cameras and test to see on a sunny and cloudy day which one works best. There are some ways to correct for such issues in software but fixing them first in hardware is normally the fastest and best way to go if possible.

With webcams and USB connections you should not need a framegrabber ... if you chose to go with NTSC cameras (which may perform better outsite) then you would need a framegrabber to convert NTSC into computer bits.

Let us know how your project goes!

c depalma from United States  [4 posts] 11 years
Thanks for the reply.  What specs should I look for that might tell me how the camera might perform under sunlight?  Lens, shutter speed, etc?

Do you know specific models that have worked?

Anonymous 11 years
That's probably a better question for the camera manufacturers as they would understand better how their cameras act in sunlight. We mainly have webcams that don't have any specs that would report these issues. What vendor are you thinking of? Are you looking into just webcams or other cameras from vendors like http://www.theimagingsource.com/ or http://www.supercircuits.com/

If anyone else here has experience with outside cameras please post examples here.

c depalma from United States  [4 posts] 11 years
I don't have anything in mind.  Just wondering if anybody had experience with it. All i want camera to do is help determine position of robot in my yard.
Anonymous 11 years
Try a quick experiment by placing your robot in the yard and take a picture (either with a webcam or a normal digital camera) of the yard and post it here. There are a couple ways to detect the robot in the yard. It gets easier if your robot is a certain color like red that could be detected ... or if it has a combination of colors or a black and white bar code or perhaps a beacon of some sort. Or you could also use an image differencing technique assuming the camera is stable and nothing else would be in the yard (do you have a cat or dog?).

Having a couple of test images helps to clarify which technique would be best ...

c depalma from United States  [4 posts] 11 years
Ok, here are the pictures of my back yard.  I live on a half acre.
The robot in its current state is the bottom half of a wheelchair.  I plan to use this thing as a lawn mower, so the chassis will likely change.  

As you can see, most of the yard is a very large hill.  ( Thats why I am using wheelchair motors.  )   The hill slopes toward the house on one side and away on the other.  Therefore, No one camera will have line of sight everywhere.

BTW, I took this picture with my Canon S3 IS Powershot.  I have a 12 x zoom lens.  ( in case anybody needs to know )

How do you think I should approach this?

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