[vtkusers] Adding a synthetic LiDAR scanner to VTK/Paraview

Sun Aug 9 17:09:29 EDT 2009

Hi David,
   Our group is just starting to get into lidar scanning of forests so your
proposed contribution does sound very interesting to us. Just a few days
back we were discussing the idea of simulating a lidar scan of a detailed
polygonal model of a single tree. This idea is to understand from first
principles what lidar returns from such a complex target look like, and in
a controlled environment where we could play around with various parameters
and see what the effect on return data is. For that exercise we were
thinking of simulating just the direct 'first order' reflections. But
longer term we are very interested in full waveform lidar data. Would your
implementation allow simulation of this? I'm guessing not as this would
require complex and slow calculations of secondary stuff like transmission,
absorbtion, re-emission and scattering.
Having a lidar simulator in Paraview would make things very convenient for
us, but if there is no other support for this we may be keen to talk to you
about what you have implemented in C++.
Actually our first problem is to get / create detailed 3D polygonal models
of trees - right down to the individual leaves - gulp - this could keep us
busy for a while yet.

regards (or should that be "many happy returns"), Dave Pont

  From:       David Doria <daviddoria+vtk at gmail.com>                                                                                            

  To:         ParaView <paraview at paraview.org>, vtkusers at vtk.org                                                                                

  Date:       08/08/2009 06:51 a.m.                                                                                                             

  Subject:    Re: [vtkusers] Adding a synthetic LiDAR scanner to VTK/Paraview                                                                   

On Thu, Jul 30, 2009 at 12:21 PM, David Doria <daviddoria+vtk at gmail.com>
wrote:
  I have written a synthetic LiDAR scanner in c++ using VTK and VXL. That
  is, rather than setting up a collection of objects in real life and
  actually sending lasers into the scene, one can simply create a scene out
  of 3d models and "scan" it by casting rays at the models. This seems like
  something that could be a huge help to any researchers that work with 3D
  model/surface/point data and LiDAR data. I'm sure many researchers have
  their own implementations - after all it is a very straightforward
  process (simply a bunch of ray triangle intersections - which I have sped
  up using VTK's octree) but I think it would be very useful to someone
  starting out in the field and to attempt to unify some datasets. I've
  used it to produce data sets for which a ground truth is known in order
  to ensure algorithms are behaving properly before moving to "real" LiDAR
  scans. Also, noise can be added to the points to attempt to simulate a
  real LiDAR scan for researchers who do not have access to the very
  expensive equipment required to obtain real scans.

  The inputs are:

  Scanner position (3D coordinate)
  Min/Max phi angle (how far "up and down" the scanner should scan)
  Min/Max theta angle (how far "left and right" the scanner should scan)
  Scanner "forward" (the phi=0, theta=0 direction)
  Angular sample spacing or number of points to acquire in the theta and
  phi directions (so the "grid" is a total of (num_theta x num_phi) points)

  The outputs are:
  A .ptx file that maintains implicitly the structure of the scan (points
  are ordered as they were taken in "strips"). This is the output given by
  a real Leica scanner.
  A .vtp file that is simply an unorganized point cloud of the scan
  returns.

  It seems like this could be a neat little thing to add to paraview - just
  a couple of text boxes and sliders to set the parameters, load the scene
  you want to scan using existing paraview I/O, visualize the scan frustrum
  using paraview line sources, and then click "Scan!" to create your ptx
  and/or vtp.

  Can I get some feedback on if this is an acceptable extension to
  vtk/paraview capabilities?

  Thanks,

  David

I didn't get any responses from this - would anyone mind responding
(negative responses are just as helpful as positive ones :) ) so I can put
this to rest or move forward, which ever the community vote turns out :).

Thanks,

David_______________________________________________
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