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List: vtkusers
Subject: Re: [vtkusers] VTK rendering pipeline - ray casting
From: Karthik Krishnan <karthik.krishnan () kitware ! com>
Date: 2011-09-30 17:20:12
Message-ID: CAKTgNuq8kr+G9RMivbs-AqLD4QzGnZP1ZiSfzrhyA_vr8GMt6A () mail ! gmail ! com
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Juan:
You would use the vtkVolumePicker (or even the vtkCellPicker, although it
ignores the cropping planes); not the prop picker, to pick the volume at a
given "opacity iso-surface". (SetVolumeOpacityIsoValue and
UseVolumeGradientOpacity)
It would have been better instead to do that based on the accumulated
opacity along the ray, until it reached a stopping opacity. I'll try to add
that at some point.
But you can pick volumes.
--
karthik
On Fri, Sep 30, 2011 at 6:20 PM, Juan Carlos Prieto <
prieto@creatis.insa-lyon.fr> wrote:
> **
> Hi Julien,
>
> Yes the 3D position, so I'm now using the vtkPropPicker, this picker will
> actually give me the world position in the actor where the hit occurred.
> I'm trying to solve another problem now. When I change the camera's
> position and view direction, the actor is not rendered unless I perform s=
ome
> interaction with the window (e.x. left click, zoom etc.), If I perform th=
e
> pick then the result is empty.
>
> The idea is to find a set of intersections given a set of rays, so I don'=
t
> know how to update the view with out the interaction.
>
> Is there a way to do this?
>
> Le 30/09/2011 14:03, Julien Finet a =E9crit :
>
> Hi Juan,
> if you use a cellpicker, keep in mind that the volume ray caster is under
> the hood a cube with 6 faces (technically, with 12triangular faces). So y=
ou
> always pick the bounds of the volume.
> Are you sure you are interested in the cell and not the 3D position ?
> julien.
>
> On Fri, Sep 30, 2011 at 7:38 AM, Juan Carlos Prieto <
> prieto@creatis.insa-lyon.fr> wrote:
>
>> Hi Julien,
>>
>> Thank you very much for the presentation, I kept on looking and I saw th=
at
>> using a vtkCellPicker might do the job of finding the intersection of a =
ray
>> against an actor in a renderer.
>> To do this, I'm moving the camera to look in the direction where I want
>> the intersection to happen, but it seems that after producing the pick, =
it
>> always finds the same cell in the actor.
>>
>> Can you give me some suggestion on how should I do this?
>>
>> Thank you very much
>>
>> Le 29/09/2011 20:22, Julien Finet a =E9crit :
>>
>> Hi Juan,
>>
>>
>> You can find a GPU ray casting high level presentation in the Kitware
>> Source of October 2009:
>> http://www.kitware.com/products/archive/kitware_quarterly0708.pdf
>>
>> Hth,
>> Julien.
>>
>> On Thu, Sep 29, 2011 at 11:54 AM, Juan Carlos Prieto <
>> prieto@creatis.insa-lyon.fr> wrote:
>>
>>> Dear VTK Users,
>>>
>>> I was wondering if anyone can point me out to the documentation of the
>>> VTK rendering pipeline, I want to analyze how the ray casting is done a=
s I
>>> came across a little problem where I need find the point of intersectio=
n in
>>> the surface.
>>>
>>> Thank you very much.
>>>
>>> --
>>> Juan Carlos Prieto
>>> Phd Student
>>> CREATIS <http://www.creatis.insa-lyon.fr> Tel:+33472438918
>>> 7 Av Jean Capelle
>>> 69621 Villeurbanne Cedex
>>> France
>>> Personal page <http://www.creatis.insa-lyon.fr/%7Eprieto>
>>>
>>> _______________________________________________
>>> Powered by www.kitware.com
>>>
>>> Visit other Kitware open-source projects at
>>> http://www.kitware.com/opensource/opensource.html
>>>
>>> Please keep messages on-topic and check the VTK FAQ at:
>>> http://www.vtk.org/Wiki/VTK_FAQ
>>>
>>> Follow this link to subscribe/unsubscribe:
>>> http://www.vtk.org/mailman/listinfo/vtkusers
>>>
>>>
>>
>> --
>> Juan Carlos Prieto
>> Phd Student
>> CREATIS <http://www.creatis.insa-lyon.fr> Tel:+33472438918
>> 7 Av Jean Capelle
>> 69621 Villeurbanne Cedex
>> France
>> Personal page <http://www.creatis.insa-lyon.fr/%7Eprieto>
>>
>
>
> --
> Juan Carlos Prieto
> Phd Student
> CREATIS <http://www.creatis.insa-lyon.fr> Tel:+33472438918
> 7 Av Jean Capelle
> 69621 Villeurbanne Cedex
> France
> Personal page <http://www.creatis.insa-lyon.fr/%7Eprieto>
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>
>
[Attachment #5 (text/html)]
Juan:<div><br></div><div>You would use the vtkVolumePicker (or even the \
vtkCellPicker, although it ignores the cropping planes); not the prop picker, to pick \
the volume at a given "opacity iso-surface". (SetVolumeOpacityIsoValue and \
UseVolumeGradientOpacity)<div> <div><br></div><div>It would have been better instead \
to do that based on the accumulated opacity along the ray, until it reached a \
stopping opacity. I'll try to add that at some \
point.</div><div><br></div><div>But you can pick volumes.</div> \
<div><br></div><div>--</div><div>karthik<br><br><div class="gmail_quote">On Fri, Sep \
30, 2011 at 6:20 PM, Juan Carlos Prieto <span dir="ltr"><<a \
href="mailto:prieto@creatis.insa-lyon.fr">prieto@creatis.insa-lyon.fr</a>></span> \
wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px \
#ccc solid;padding-left:1ex;"><u></u>
<div bgcolor="#ffffff" text="#000000">
Hi Julien, <br>
<br>
Yes the 3D position, so I'm now using the vtkPropPicker, this picker
will actually give me the world position in the actor where the hit
occurred. <br>
I'm trying to solve another problem now. When I change the camera's
position and view direction, the actor is not rendered unless I
perform some interaction with the window (e.x. left click, zoom
etc.), If I perform the pick then the result is empty. <br>
<br>
The idea is to find a set of intersections given a set of rays, so I
don't know how to update the view with out the interaction. <br>
<br>
Is there a way to do this?<br>
<br>
Le 30/09/2011 14:03, Julien Finet a écrit :
<div><div></div><div class="h5"><blockquote type="cite">Hi Juan,
<div>if you use a cellpicker, keep in mind that the volume ray
caster is under the hood a cube with 6 faces (technically, with
12triangular faces). So you always pick the bounds of the
volume.</div>
<div>Are you sure you are interested in the cell and not the 3D
position ?</div>
<div>julien.<br>
<br>
<div class="gmail_quote">On Fri, Sep 30, 2011 at 7:38 AM, Juan
Carlos Prieto <span dir="ltr"><<a \
href="mailto:prieto@creatis.insa-lyon.fr" \
target="_blank">prieto@creatis.insa-lyon.fr</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt \
0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex"> <div \
bgcolor="#ffffff" text="#000000"> Hi Julien, <br> <br>
Thank you very much for the presentation, I kept on
looking and I saw that using a vtkCellPicker might do the
job of finding the intersection of a ray against an actor
in a renderer. <br>
To do this, I'm moving the camera to look in the direction
where I want the intersection to happen, but it seems that
after producing the pick, it always finds the same cell in
the actor. <br>
<br>
Can you give me some suggestion on how should I do this? <br>
<br>
Thank you very much<br>
<br>
Le 29/09/2011 20:22, Julien Finet a écrit :
<div>
<div>
<blockquote type="cite">Hi Juan,
<div><br>
</div>
<div><br>
</div>
<div>You can find a GPU ray casting high level
presentation in the Kitware Source of October
2009:
<div><a \
href="http://www.kitware.com/products/archive/kitware_quarterly0708.pdf" \
target="_blank">http://www.kitware.com/products/archive/kitware_quarterly0708.pdf</a></div>
<div><br>
</div>
<div>Hth,</div>
<div>Julien.<br>
<br>
<div class="gmail_quote">On Thu, Sep 29, 2011 at
11:54 AM, Juan Carlos Prieto <span dir="ltr"><<a \
href="mailto:prieto@creatis.insa-lyon.fr" \
target="_blank">prieto@creatis.insa-lyon.fr</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt \
0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex"> <div \
bgcolor="#ffffff" text="#000000"> Dear VTK Users, <br>
<br>
I was wondering if anyone can point me out
to the documentation of the VTK rendering
pipeline, I want to analyze how the ray
casting is done as I came across a little
problem where I need find the point of
intersection in the surface. <br>
<br>
Thank you very much. <br>
<font color="#888888"> <br>
<div>-- <br>
Juan Carlos Prieto <font face="arial" color="grey" \
size="2"> <br> Phd Student <br>
<a href="http://www.creatis.insa-lyon.fr" \
target="_blank">CREATIS</a> Tel:<a href="tel:%2B33472438918" value="+33472438918" \
target="_blank">+33472438918</a> <br> 7 Av Jean Capelle <br>
69621 Villeurbanne Cedex <br>
France <br>
<a \
href="http://www.creatis.insa-lyon.fr/%7Eprieto" target="_blank">Personal page</a> \
</font> </div> </font></div>
<br>
_______________________________________________<br>
Powered by <a href="http://www.kitware.com" \
target="_blank">www.kitware.com</a><br> <br>
Visit other Kitware open-source projects at
<a \
href="http://www.kitware.com/opensource/opensource.html" \
target="_blank">http://www.kitware.com/opensource/opensource.html</a><br> <br>
Please keep messages on-topic and check the
VTK FAQ at: <a href="http://www.vtk.org/Wiki/VTK_FAQ" \
target="_blank">http://www.vtk.org/Wiki/VTK_FAQ</a><br> <br>
Follow this link to subscribe/unsubscribe:<br>
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target="_blank">http://www.vtk.org/mailman/listinfo/vtkusers</a><br> <br>
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
<br>
<div>-- <br>
Juan Carlos Prieto <font face="arial" color="grey" size="2"> <br>
Phd Student <br>
<a href="http://www.creatis.insa-lyon.fr" \
target="_blank">CREATIS</a> Tel:<a href="tel:%2B33472438918" value="+33472438918" \
target="_blank">+33472438918</a> <br>
7 Av Jean Capelle <br>
69621 Villeurbanne Cedex <br>
France <br>
<a href="http://www.creatis.insa-lyon.fr/%7Eprieto" \
target="_blank">Personal page</a> </font> </div> </div>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</blockquote>
<br>
<div>-- <br>
Juan Carlos Prieto
<font face="arial" color="grey" size="2">
<br>
Phd Student
<br>
<a href="http://www.creatis.insa-lyon.fr" target="_blank">CREATIS</a>
Tel:+33472438918
<br>
7 Av Jean Capelle
<br>
69621 Villeurbanne Cedex
<br>
France <br>
<a href="http://www.creatis.insa-lyon.fr/%7Eprieto" target="_blank">Personal
page</a>
</font>
</div>
</div></div></div>
<br>_______________________________________________<br>
Powered by <a href="http://www.kitware.com" target="_blank">www.kitware.com</a><br>
<br>
Visit other Kitware open-source projects at <a \
href="http://www.kitware.com/opensource/opensource.html" \
target="_blank">http://www.kitware.com/opensource/opensource.html</a><br> <br>
Please keep messages on-topic and check the VTK FAQ at: <a \
href="http://www.vtk.org/Wiki/VTK_FAQ" \
target="_blank">http://www.vtk.org/Wiki/VTK_FAQ</a><br> <br>
Follow this link to subscribe/unsubscribe:<br>
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target="_blank">http://www.vtk.org/mailman/listinfo/vtkusers</a><br> \
<br></blockquote></div><br></div></div></div>
_______________________________________________
Powered by www.kitware.com
Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
Follow this link to subscribe/unsubscribe:
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