Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Rebelgium on November 29, 2007, 03:47:35 PM

Title: laser line visibillity on camera
Post by: Rebelgium on November 29, 2007, 03:47:35 PM

I'm planning to use these lasers with a line-lens attached to it. The laser line will be filmed by a camera (cmucam or similar) which is mounted on the front of my robot.
http://cgi.ebay.com/650nm-5mW-laser-LINE-module-3VDC-Full-Brass-Case_W0QQitemZ160184169031QQihZ006QQcategoryZ53141QQcmdZViewItem (http://cgi.ebay.com/650nm-5mW-laser-LINE-module-3VDC-Full-Brass-Case_W0QQitemZ160184169031QQihZ006QQcategoryZ53141QQcmdZViewItem)

I know the laser line is filtered out of the image by selecting only the brightest pixels, ( can it also be the brightest RED pixels? I think it would give much better result...)
but I was wondering how far the wall/obstacle can be from the robot, and the laser would still be strong enough to be filtered out as the brightest pixels?

Does anyone have any experience with this?


And if the laser would be to weak to be filtered out as the brightest pixels in a too short distance, what could I do about it?
I've thought of buy two (or more) lasers and letting them shine on top of eachother... (double intensity)

Title: Re: laser line visibillity on camera
Post by: Kohanbash on November 29, 2007, 07:35:14 PM

Hi
What you are trying to do is usually called light stripping.
The "what and "how far" you can see are greatly dependant on the background of the laser line, and its angle relative to the ground. The biggest issue of detecting the line is in your line/color detection algorithm implementation.

Title: Re: laser line visibillity on camera
Post by: dunk on November 29, 2007, 07:35:59 PM

hi Rebelgium,
have you seen this thread?
http://www.societyofrobots.com/robotforum/index.php?topic=2220.0 (http://www.societyofrobots.com/robotforum/index.php?topic=2220.0)

my post half way through (the one with the pictures) answers most of your questions.

Quote

I know the laser line is filtered out of the image by selecting only the brightest pixels, ( can it also be the brightest RED pixels? I think it would give much better result...)
but I was wondering how far the wall/obstacle can be from the robot, and the laser would still be strong enough to be filtered out as the brightest pixels?

this is not the simplest way to do it. there could conceivably be something brighter in the room than the laser line. (unless you only use it at night...)

i subtract an image with the laser switched off from an image of the laser switched on to get only the pixels lit by the laser.
the pictures in the thread above demonstrate this better than my description.

dunk.