[vtkusers] vtk Coordinate system clarification

Scott Johnson Scott.Johnson at neuwave.com
Mon Apr 5 17:16:37 EDT 2010


I've got one quick follow up to this.  If I get the coordinate of a
CellId, such as returned by a vtkCellPicker, which happens to be an
image, is the returned coordinate the center of the voxel or a corner?
If it's a corner, which one?

 

Thanks

 

                                -- Scott

 

From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On
Behalf Of Scott Johnson
Sent: Monday, April 05, 2010 3:47 PM
To: Darshan Pai
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] vtk Coordinate system clarification

 

Thanks Darshan.

 

                                -- Scott

 

From: Darshan Pai [mailto:darshanpai at gmail.com] 
Sent: Monday, April 05, 2010 3:36 PM
To: Scott Johnson
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] vtk Coordinate system clarification

 

All visualization should be in WorldCoordinate space 

On Mon, Apr 5, 2010 at 4:29 PM, Scott Johnson
<Scott.Johnson at neuwave.com> wrote:

Hi Folks,

 

I'm running into issues trying to spatially coordinate the display of
images and polygons (spheres in this case).  My ultimate goal is to
express all coordinates in the DICOM Frame of Reference.

 

Right now I'm trying to display axial, sagittal, and coronal slices and
the intersection of those image planes with spheres.  I'm using
vtkImageReslice to slice the images, and vtkCutter to extract the
contours of the intersection, but am running into problems getting the
sliced polygons to show up in the right place with respect to the
images.  I can get the spheres to display in the correct location in a
MIP rendering.

 

My difficulty is understanding in what coordinate system everything but
images are expressed in.  (I've read the Coordinate System section in
the new version of the VTK User's guide.)  For example, if I set the
position of a vtkSphereSource with SetCenter is that in pixel
coordinates in the coordinate system, or is it an absolute location in
space?  The same goes for a vtkPlane:  What coordinate system should
locations passed to SetOrigin be in?

 

My thought was that everything was expressed in the World coordinate
system and the world coordinate system was established by the images,
but that doesn't seem to be working for me.

 

Thanks

 

                                -- Scott


_______________________________________________
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

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20100405/605f5b14/attachment.htm>


More information about the vtkusers mailing list