[vtk-developers] [Non-DoD Source] Re: merge request for vtkCamera.cxx eyeseparation and near far planes correction (UNCLASSIFIED)

Fri Mar 18 08:42:43 EDT 2016

CLASSIFICATION: UNCLASSIFIED

The application would still set the eyeseparation with my changes. What I have 
done is correct a mismatch between what is shown on the server side screen 
with what is generated on the same size screen when visualized in the ParaView 
client RenderWindow. The correction I have added for eyeseparation scaling 
with distance to the object is a close approximation of what is already being 
displayed when the ParaView client RenderWindow displays stereo data. There 
were 2 may problems a mismatch of separation across all scales, which I have 
corrected as well as an additional  mismatch for very small data (of sizes 
less than 1) which I have also corrected. The eyeseparation  now produces 
similar results to what is generated for the ParaView client RenderWIndow. The 
near and far planes changes were necessary as they were hard coded constants 
and did not scale with the size of the data. This was particularly noticeable 
for data scaled at 0.001 or smaller, where the data would be clipped out of 
visibility on the server side display but would show up just fine in the 
ParaView client RenderWindow. By changing the near and far plane to be 
relative to the data, I am now more closely approximating what can be seen in 
the ParaView client RenderWindow and can visually data across a wide range of 
scales. I have tested this routing across scales from 1,000,000 X to 
1/1,000,000 X and at every intermediate scale of 10 and the data now clips in 
a way  that closely approximates the way it clips in the ParaView client 
RenderWindow.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Joseph G. Hennessey Ph.D., Lockheed Martin Army Research Lab DOD 
Supercomputing Resource Center

-----Original Message-----
From: vtk-developers [mailto:vtk-developers-bounces at vtk.org] On Behalf Of 
David Gobbi
Sent: Thursday, March 17, 2016 5:15 PM
To: David Cole <DLRdave at aol.com>
Cc: paraview-developers at paraview.org; vtk-developers at vtk.org
Subject: [Non-DoD Source] Re: [vtk-developers] merge request for vtkCamera.cxx 
eyeseparation and near far planes correction (UNCLASSIFIED)

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Considering that vtkCamera doesn't know the physical size of the screen, I 
certainly hope that EyeSeparation is not in meters or any other absolute 
units!  It should be in units relative to the screen size.  And, since only 
the application itself knows the physical screen size, it is up to the 
application
to set it appropriately.   The eye separation is much smaller relative to a
huge wall screen, than to a workstation display.

Just agreeing with the other David here...

 - David

On Thu, Mar 17, 2016 at 2:44 PM, David Cole via vtk-developers 
<vtk-developers at vtk.org < Caution-mailto:vtk-developers at vtk.org > > wrote:

	OffAxis projection in VTK is woefully underdocumented, and accepting
	this pull request will only add to the mystery.

	I would suggest documenting that the coordinates used to specify it
	are in vtkCamera coordinates (not world), and clarifying with comments
	in the code what some of the constants used are for. Also,
	EyeSeparation appears to be specified in meters, although it's unclear
	how it relates to any of the VTK coordinate systems or to the size of
	the actual display being used.

	2 cents,
	David C.

	On Thu, Mar 17, 2016 at 4:17 PM, Aashish Chaudhary
	<aashish.chaudhary at kitware.com < Caution-mailto:aashish.chaudhary at kitware.com 
 > > wrote:
	> Hi Joe,
	>
	> Thank for you for the PR. Could you please describe the problem in bit more
	> detail?
	>
	> Thanks,
	>
	>
	> On Thu, Mar 17, 2016 at 4:04 PM, Hennessey, Joseph G CTR USARMY RDECOM ARL
	> (US) <joseph.g.hennessey2.ctr at mail.mil < 
Caution-mailto:joseph.g.hennessey2.ctr at mail.mil > > wrote:
	>>
	>> CLASSIFICATION: UNCLASSIFIED
	>>
	>> Hello,
	>>
	>> I have modified
	>>
	>> Rendering/Core/vtkCamera.cxx:: ComputeOffAxisProjectionFrustum
	>>
	>> To fix a problem with eyeseparation and near and far planes for use with
	>> immersive paraview
	>>
	>> The merge request is called
	>>
	>> fix ComputeOffAxisProjectionFrustum eyeseparation and near and far planes.
	>>
	>>
	>> 
Caution-https://gitlab.kitware.com/vtk/vtk/commit/4fe4fabb420bba77740ec988d060c5c296 
< 
Caution-https://gitlab.kitware.com/vtk/vtk/commit/4fe4fabb420bba77740ec988d060c5c296 
 >
	>> d36afb
	>>
	>> Commit 4fe4fabb420bba77740ec988d060c5c296d36afb
	>>
	>> Authored by Joseph G. Hennessey about an hour ago
	>> 1 parent d52198e1
	>>
	>> Please add this to VTK and indirectly to ParaView
	>>
	>> Thanks,
	>>
	>> Joe
	>>
	>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	>> Joseph G. Hennessey Ph.D., Lockheed Martin
	>> Army Research Lab
	>> DOD Supercomputing Resource Center
	>>
	>>
	>> CLASSIFICATION: UNCLASSIFIED
	>>
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	>
	> --
	> | Aashish Chaudhary
	> | Technical Leader
	> | Kitware Inc.
	> | Caution-http://www.kitware.com/company/team/chaudhary.html < 
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