Calibration Plate

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Calibration Plate

Hang Dong
We are looking for a high quality calibration target (something beyond pdf printout pasted on a plate) like the 4x4 checkerboard shown in the pr2 calibration page: http://www.ros.org/wiki/pr2_calibration/Tutorials/Calibrating%20the%20PR2

Is it possible to purchase one directly from willow garage or a distributor, or any hint one how to go about making one ourselves?

Thanks,

Hang
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Re: Calibration Plate

Bill Morris
On Tue, 2010-11-02 at 13:39 -0700, Hang Dong wrote:

> We are looking for a high quality calibration target (something beyond pdf
> printout pasted on a plate) like the 4x4 checkerboard shown in the pr2
> calibration page:
> http://www.ros.org/wiki/pr2_calibration/Tutorials/Calibrating%20the%20PR2
>
> Is it possible to purchase one directly from willow garage or a distributor,
> or any hint one how to go about making one ourselves?
>
> Thanks,
>
> Hang

We make ours by printing the checkerboard on a large sheet of paper then
using a spray adhesive like "Super77" to affix the paper to a piece of
cardboard or foamcore.


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Re: Calibration Plate

von Wichert, Georg
For good calibrations the pattern should be as planar as possible, cardboard as a carrier might actually be a little problematic, we used particle boards instead.

Another option is to use the nearest internet photoservice and let them print the pattern on "aluminum dibond". Depending on the service provider the scaling can vary, so it s best to call them in advance and ask for the best method to preserve the size. Otherwise the dimensions have to be measured afterwards.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill Morris
Sent: Tuesday, November 02, 2010 11:41 PM
To: User discussions
Subject: Re: [ros-users] Calibration Plate

On Tue, 2010-11-02 at 13:39 -0700, Hang Dong wrote:

> We are looking for a high quality calibration target (something beyond
> pdf printout pasted on a plate) like the 4x4 checkerboard shown in the
> pr2 calibration page:
> http://www.ros.org/wiki/pr2_calibration/Tutorials/Calibrating%20the%20
> PR2
>
> Is it possible to purchase one directly from willow garage or a
> distributor, or any hint one how to go about making one ourselves?
>
> Thanks,
>
> Hang

We make ours by printing the checkerboard on a large sheet of paper then using a spray adhesive like "Super77" to affix the paper to a piece of cardboard or foamcore.


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Re: Calibration Plate

Hang Dong
In reply to this post by Bill Morris
Thanks for the information.

One issue we had with our printout is that there is always small amount of scaling from print shops, hence having to measure the size of square again and introduce a bit more uncertainty. Ideally we want one made with high level of flatness and precision, i found this one from cognex: 24x24 calibration plate, but unfortunately it also comes with some proprietary marking.
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Re: Calibration Plate

von Wichert, Georg
Yes,scaling can be an issue. If you find someone with a "printing mindset" who can send PS or PDF to the printer and where you can tell the actual printing guy not to scale, the scaling will likely be not an issue. We had such a service in our neighborhood, but it unfortunately closed down in the meantime.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Hang Dong
Sent: Wednesday, November 03, 2010 8:29 PM
To: [hidden email]
Subject: Re: [ros-users] Calibration Plate


Thanks for the information.

One issue we had with our printout is that there is always small amount of scaling from print shops, hence having to measure the size of square again and introduce a bit more uncertainty. Ideally we want one made with high level of flatness and precision, i found this one from cognex:
http://www.cognex.com/support/downloads/File.aspx?d=1910 24x24 calibration plate , but unfortunately it also comes with some proprietary marking.
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Re: Calibration Plate

Hang Dong
wow, flat and light weight! this aluminum dibond looks like exactly what we need for a portable calibration target. Thank you! I will try find a local print shop and check it out in person.

Hang

got off a http://www.seenby.com/ page:
Aluminum Dibond is a sound composite of two aluminum plates and a PVC core (the “bond”). Despite its very light weight, it guarantees a level surface and has great resistance to deformation. Once the image is printed, it will be permanently mounted to the surface of the aluminum dibond board with a special adhesive making it perfectly smooth and exact. Once mounted, the image will be laminated for protection against damage and ultraviolet light. The back of the board has rails that serve as the hanging mechanism, allowing for a frameless gallery look.
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Re: Calibration Plate

Vijay Pradeep
Hello Hang,

We use a dibond plate with the PR2, and we are happy with the results.  Willow Garage is currently not selling this specific part, but you can contact the vendor directly and ask for a quote.

Information about spare parts and accessories for the PR2 are available here: http://pr2support.willowgarage.com/wiki/PR2%20Parts
The part that you'll want is under the Accessory Tab in the embedded google doc.

Part #: 68-03823
Description: Small Calibration Checkerboard
Vendor: Ideation Signs & Communications, Inc.
http://www.ideationsigns.com/

Here is a picture of the PR2 plate: http://www.ros.org/wiki/pr2_calibration/SubTutorials/Capture%20Data?action=AttachFile&do=get&target=hand_cb.png

Vijay Pradeep

On Wed, Nov 3, 2010 at 2:38 PM, Hang Dong <[hidden email]> wrote:

wow, flat and light weight! this aluminum dibond looks like exactly what we
need for a portable calibration target. Thank you! I will try find a local
print shop and check it out in person.

Hang

got off a http://www.seenby.com/ page:
Aluminum Dibond is a sound composite of two aluminum plates and a PVC core
(the “bond”). Despite its very light weight, it guarantees a level surface
and has great resistance to deformation. Once the image is printed, it will
be permanently mounted to the surface of the aluminum dibond board with a
special adhesive making it perfectly smooth and exact. Once mounted, the
image will be laminated for protection against damage and ultraviolet light.
The back of the board has rails that serve as the hanging mechanism,
allowing for a frameless gallery look.
--
View this message in context: http://ros-users.122217.n3.nabble.com/Calibration-Plate-tp1830575p1837747.html
Sent from the ROS-Users mailing list archive at Nabble.com.
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--
Vijay Pradeep
Systems Engineer
Willow Garage, Inc.
[hidden email][hidden email]


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Re: Calibration Plate

Hang Dong
Thank you sir!