[ros-users] Hokuyo intensity values

[Vijay Pradeep]

Hi Abe,

It's great to hear that you're interested in using Hokuyo intensity data.
I'm not certain as to how much intensity data is being used in our point
cloud processing pipelines.  I think intensity might be used in our door
handle detector.  Someone else can elaborate further on this.

Intensity data is a critical part of the pr2_calibration stack.  We use
intensity images (just like what was on the 'Scanner_to_camera_calibration'
page) to extract checkerboard corners, which is the first step in a much
larger full system calibration procedure.

*it seems that the values are normally somewhere between 0 and 6000. However
every once in a while, they'll go as high as ~15000.*
I can agree with the 0-6000 intensity estimate, but I've definitely also
seen spurious bright returns.  I haven't really paid attention to how large
these returns get (maybe they are in fact ~15000), but I have noticed that
the spurious bright returns occur most often when rays glance off the edges
of objects.

*it says that the intensity is a function of distance... is there a good way
to normalise out the distance factor so that intensity values can be
compared on a normalised 0 to 1 range?
*I don't believe anyone here has tried to build an intensity/range model,
probably because we don't have a strong use case for this type of
normalization.  Somewhat related, I'd be curious to see how intensity data
could be used to compensate for range biases.

I'm definitely interested in hearing how you end up using the intensity
data!

Vijay

On Tue, Apr 13, 2010 at 4:57 PM, Abe Bachrach <abachrach at gmail.com> wrote:

> Hi there,
> I started looking at the intensity values that you can get from the hokuyo
> UTM laser scanners, but was seeing a much wider fluctuation in the values
> than I would have expected...
> from looking at my own data, and the data posted on the calibration wiki
> http://pr.willowgarage.com/wiki/Scanner_to_camera_calibration
>
> it seems that the values are normally somewhere between 0 and 6000. However
> every once in a while, they'll go as high as ~15000.
>
> In the documentation posted here:
>
> http://www.ros.org/wiki/hokuyo_node?action=AttachFile&do=get&target=UTM-30LX_Specification.pdf
> it says that the intensity is a function of distance... is there a good way
> to normalise out the distance factor so that intensity values can be
> compared on a normalised 0 to 1 range?
>
> How have you guys generally worked with the intensity info.
>
> thanks in advance!
> -=Abe
>
>
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