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Video P*r*o*b*i*n*g / Re: New 3d Video Probe
« on: July 29, 2009, 06:38:09 AM »
Hello Eero,
> If I understand right the direction of the laserline can be chosen
> according to ones own needs.
Yes, that was the plan. More accurately the camera plus laser line assembly can be oriented as you wish. The relationship between the camera and the laser is fixed. The laser plane must be perpendicular to the camera lens axis.
> For me this would be parallel to X-axis
That is the way Art arranged his. Mine should work there as well.
> ( I tried parallel to Y-axis as well, problems are the same).
I presume that you calibrate for whichever axis that you are using.
> I have both the camera and the laser pointing down at 45 degrees
> so the camera is looking perpendicularly at the line (in the middle of
> its vertical field of view).
Sounds ok but I would like to see a photo or a drawing that shows the camera, the laser module, and the laser line. Can you post photos or links here for the benefit of others?
> I have a nice focusable line laser and Watchport V3 camera with a
> set of different lenses (tried 8mm F2.0 and 12mm F2.0). I have as
> well a Logitech QuickCam Pro. The Watchport has a problem of a
> bigger distortion of the picture (a straight line seen as slightly bent).
The longer focal length will usually have less distortion. Smaller field of view means more magnification for more detail too. Can you identify the lenses or the source? Are they part of the set that is sold for the Watchport or did you maybe find them on ebay.
> The QuickCam has a zoom that demands a calibration every time you
> plug it in after having disconnected it for milling work.
I can see where that would be very inconvenient.
> With Art's videoprobe the quickCam gave ok results but took always a lot of time setting up - the Watchport was useless.
I was able to use the Watchport/V2 with Art's plugin. I don't have a V3 to test with but I would expect it to work ok. I have one out for repair so may know more when it returns.
> With your Scan3D I understood the calibration should take care of -
> at least some of - the distortion.
That is the plan but not tested a lot. It seems to work on my setup but I use a lens that seems to have little distortion anyway. The math can be made to fix worse distortion. I just need to see some bad results first.
> And what's nice no calibration needed every time before a scan.
That was just a matter of saving the cal data. I think Art just did not get around to doing that when he was tinkering.
The problems:
1) I can't get the calibration process - done as you describe in the
> short manual - to correct the "bending". This is easy to see by
> scanning a flat surface with two parallel passes resulting to two
> "trays" with edges not meeting.
Sounds like the calibration may not have been done. The defaults should produce something recognizable but probably do little to correct distortion. I would like to see the data files and photos of the scan setup.
2)As I understand the calibration should automatically correct any slight
> deviation in the direction of the camera in relation to the laserline. I still
> get the edges of two adjacent passes not meeting but as two slightly
> inclined bands. (This is easier to see using the QuickCam as the scan is not "bent")
I am not following you. I need to see the setup and the results.
3)The whole of these problems may be a result of some of the calibration
> process missing... In the Scan3D window after calibration the fields for
> FOVs, Elevation and Azimuth all show "1". ?
I think those are default values. You should get something like 45 degrees for elevation for your setup. It is possible that the point of the needle is not being seen or that the calibration scan not working right.
You need to be sure that the needle point is detected by the camera when the laser hits the point. That should be the only thing visible during the cal scan. You probably need to set the camera exposure time to a small value, like 1ms, so that the field is black except for a small area where the laser hits the point of the calibration needle.
I am guessing by your numbers that you are using mm. I tested with inches but that should not matter.
Is the camera upside down or right side up or sideways? Photos of your hardware off the machine and on the machine would tell me a lot.
The camera orientation needs to be selected so that the line is horizontal in the second display. Ideally, that view should appear right side up for the part but would probably work upside down too. The line should not appear vertical in the second view.
Tom Hubin
thubin@earthlink.net
> If I understand right the direction of the laserline can be chosen
> according to ones own needs.
Yes, that was the plan. More accurately the camera plus laser line assembly can be oriented as you wish. The relationship between the camera and the laser is fixed. The laser plane must be perpendicular to the camera lens axis.
> For me this would be parallel to X-axis
That is the way Art arranged his. Mine should work there as well.
> ( I tried parallel to Y-axis as well, problems are the same).
I presume that you calibrate for whichever axis that you are using.
> I have both the camera and the laser pointing down at 45 degrees
> so the camera is looking perpendicularly at the line (in the middle of
> its vertical field of view).
Sounds ok but I would like to see a photo or a drawing that shows the camera, the laser module, and the laser line. Can you post photos or links here for the benefit of others?
> I have a nice focusable line laser and Watchport V3 camera with a
> set of different lenses (tried 8mm F2.0 and 12mm F2.0). I have as
> well a Logitech QuickCam Pro. The Watchport has a problem of a
> bigger distortion of the picture (a straight line seen as slightly bent).
The longer focal length will usually have less distortion. Smaller field of view means more magnification for more detail too. Can you identify the lenses or the source? Are they part of the set that is sold for the Watchport or did you maybe find them on ebay.
> The QuickCam has a zoom that demands a calibration every time you
> plug it in after having disconnected it for milling work.
I can see where that would be very inconvenient.
> With Art's videoprobe the quickCam gave ok results but took always a lot of time setting up - the Watchport was useless.
I was able to use the Watchport/V2 with Art's plugin. I don't have a V3 to test with but I would expect it to work ok. I have one out for repair so may know more when it returns.
> With your Scan3D I understood the calibration should take care of -
> at least some of - the distortion.
That is the plan but not tested a lot. It seems to work on my setup but I use a lens that seems to have little distortion anyway. The math can be made to fix worse distortion. I just need to see some bad results first.
> And what's nice no calibration needed every time before a scan.
That was just a matter of saving the cal data. I think Art just did not get around to doing that when he was tinkering.
The problems:
1) I can't get the calibration process - done as you describe in the
> short manual - to correct the "bending". This is easy to see by
> scanning a flat surface with two parallel passes resulting to two
> "trays" with edges not meeting.
Sounds like the calibration may not have been done. The defaults should produce something recognizable but probably do little to correct distortion. I would like to see the data files and photos of the scan setup.
2)As I understand the calibration should automatically correct any slight
> deviation in the direction of the camera in relation to the laserline. I still
> get the edges of two adjacent passes not meeting but as two slightly
> inclined bands. (This is easier to see using the QuickCam as the scan is not "bent")
I am not following you. I need to see the setup and the results.
3)The whole of these problems may be a result of some of the calibration
> process missing... In the Scan3D window after calibration the fields for
> FOVs, Elevation and Azimuth all show "1". ?
I think those are default values. You should get something like 45 degrees for elevation for your setup. It is possible that the point of the needle is not being seen or that the calibration scan not working right.
You need to be sure that the needle point is detected by the camera when the laser hits the point. That should be the only thing visible during the cal scan. You probably need to set the camera exposure time to a small value, like 1ms, so that the field is black except for a small area where the laser hits the point of the calibration needle.
I am guessing by your numbers that you are using mm. I tested with inches but that should not matter.
Is the camera upside down or right side up or sideways? Photos of your hardware off the machine and on the machine would tell me a lot.
The camera orientation needs to be selected so that the line is horizontal in the second display. Ideally, that view should appear right side up for the part but would probably work upside down too. The line should not appear vertical in the second view.
Tom Hubin
thubin@earthlink.net
but would be glad to use it