Zero intermediate returns?

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Enzo Campomanes

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Jun 22, 2016, 2:10:46 AM6/22/16
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Hello,

Just a quick question, is it possible to get no/zero intermediate returns in a single tile of LiDAR data? Esp. that the area is covered with trees?

Thanks.

--
Florencio P. Campomanes V

Supervising Science Research Specialist, UP Cebu Phil-LiDAR 2

enzo.campomanesv

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Jun 22, 2016, 2:12:20 AM6/22/16
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Hello,

Just a quick question, is it possible to get no/zero intermediate returns in a single tile of LiDAR data? Esp. that the area is covered with trees?



Thanks.

Martin Isenburg

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Jun 22, 2016, 5:21:22 AM6/22/16
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Hello Enzo,

According to the lasinfo report all but 5,869 points come from a laser pulse that produced only a *single* return. Those 5,869 points that come from a multi-return are all from a laser pulse that produced only *two* returns: first and last. In order to have intermediate returns you will need to have a laser pulse that produces at least three returns. But if you see that line that states "overview of number of returns of given pulse" then you see that the histogram has non-zero entries only for one (2,316,845) and two (5,869) returns.

If this is data from a modern LiDAR scanner above a typical forested area then this low level of canopy penetration suggests that either the scanner hardware was broken (e.g. very low energy emitted per pulse or receiver lense covered with dirt) or that something went wrong in the post processing. 

Regards,

Martin @rapidlasso


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