How to estimate distance between two point coordinates in mm ?

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How to estimate distance between two point coordinates in mm ?

slinzex
Hi,

I've searched this through the forum and I get no solution. I see that there's no specific unit for point coordinates. Am I wrong in this? Maybe nowadays is something implemented already?

I need to get the difference between this two points for example, but in mm:

x = -9.087109, y = 190.829269, z = 1046.500000
x = 9.284196, y = 158.605423, z = 891.000000

If there is no unit, how can I determine one?

Maybe (homemade solution) using some kind of proportion between the real distance between my eyes in real world and in point cloud representation ... ?
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Re: How to estimate distance between two point coordinates in mm ?

aichim
Administrator
Hi,

There is no default unit in PCL. We generally assume meters for default parameters for algorithms or when grabbing data with OpenNI. But you are free to use whatever you like.

Cheers,
Alex

On Apr 12, 2013, at 1:02 PM, slinzex <[hidden email]> wrote:

> Hi,
>
> I've searched this through the forum and I get no solution. I see that
> there's no specific unit for point coordinates. Am I wrong in this? Maybe
> nowadays is something implemented already?
>
> I need to get the difference between this two points for example, but in mm:
>
> x = -9.087109, y = 190.829269, z = 1046.500000
> x = 9.284196, y = 158.605423, z = 891.000000
>
> If there is no unit, how can I determine one?
>
> Maybe (homemade solution) using some kind of proportion between the real
> distance between my eyes in real world and in point cloud representation ...
> ?
>
>
>
> --
> View this message in context: http://www.pcl-users.org/How-to-estimate-distance-between-two-point-coordinates-in-mm-tp4027239.html
> Sent from the Point Cloud Library (PCL) Users mailing list mailing list archive at Nabble.com.
> _______________________________________________
> [hidden email] / http://pointclouds.org
> http://pointclouds.org/mailman/listinfo/pcl-users
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Re: How to estimate distance between two point coordinates in mm ?

slinzex
This post was updated on .
Hey, thanks for quick answer.
But how much you can trust that assumption? Is it precise to assume meters?

Can I transform by proportions as I said before?

Basically what I need is to estimate an error of my program testing on some images of groundtruth.

For example I have measured the distance between my nose and chin and it's 800 mm.
However in my pointcloud it results
x = 177.548141, y = 76.620781, z = 717.710510
x = 168.723236, y = 92.144066, z = 717.000000
so 92-76 =16 ??? How can I relate this?