[Ros-kinect] Interesting systematic noise in calculated normals

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[Ros-kinect] Interesting systematic noise in calculated normals

Johan Granberg
Hello. I am working on a project in wich i will be using the surface normals from a pointcloud to do some machine learning. I have used the class pcl::IntegralImageNormalEstimation to do get the normals, however im getting some interesting noise in the normals.

Above i have appended an image in which i have put the normals of a point cloud(normal.normal_x = red channel, normal.normal_y = green channel and normal.normal_z = blue channel).

The image contains a flat wall and the side of a bookshelf. If you see the image it is pretty obvious that there is some kind of systematic noise in the image( wavelike and diagonal). Simmilar noise is present in all the images of my enviorment that i have taken.

So now to the question: What is the reason for this problem?

My suggestions:
The kinnect has some small systematic error in the depth data?
My kinnect is not calibrated well enough?
I did something stupid?

What do you think?

Cheers, Johan Granberg

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Re: [Ros-kinect] Interesting systematic noise in calculated normals

Tully Foote
Depending on your view point.  I expect that you're seeing the discretization of the range measurements. 

Tully

On Mon, Feb 28, 2011 at 6:03 AM, Johan Granberg <[hidden email]> wrote:
Hello. I am working on a project in wich i will be using the surface normals from a pointcloud to do some machine learning. I have used the class pcl::IntegralImageNormalEstimation to do get the normals, however im getting some interesting noise in the normals.

Above i have appended an image in which i have put the normals of a point cloud(normal.normal_x = red channel, normal.normal_y = green channel and normal.normal_z = blue channel).

The image contains a flat wall and the side of a bookshelf. If you see the image it is pretty obvious that there is some kind of systematic noise in the image( wavelike and diagonal). Simmilar noise is present in all the images of my enviorment that i have taken.

So now to the question: What is the reason for this problem?

My suggestions:
The kinnect has some small systematic error in the depth data?
My kinnect is not calibrated well enough?
I did something stupid?

What do you think?

Cheers, Johan Granberg

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--
Tully Foote
Systems Engineer
Willow Garage, Inc.
[hidden email]
(650) 475-2827

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