[vtkusers] vtkPointPicker Accuracy

[Paul]

Hi Christopher,

We had a very similar problem. (BTW, I notice you're at Queen's.
Are you familiar with HRMC?  They are also at Queen's and my
company works with them in the area of computer-assisted
surgery).

In our case we are using the vtkPropPicker (actually, a derivation
of it...) and calling GetPickedPoint().  However, the point is not
quite on the mesh.

Unfortunately, while some pickers allow setting a tolerance for
the picking I couldn't do that.  My solution was to take the point
returned by the picker, which was *very* close to the mesh, and then
find the exact point on the mesh that was closest to this.

I accomplished by using the poly data of the mesh (vtkPolyData)
passing the almost right point to vtkPolyData's FindPoint() method and
passing the result of that to vtkPolyData's GetPoint() method.

HTH,
Paul St. John.
Visible Bytes Software
www.visible-bytes.com


-----Original Message-----
From: vtkusers-admin at public.kitware.com
[mailto:vtkusers-admin at public.kitware.com]On Behalf Of Christopher
Bayley
Sent: 30/01/2003 9:12 AM
To: vtkusers at public.kitware.com
Subject: [vtkusers] vtkPointPicker Accuracy


Hello Everyone;

Am am using an instance vtkPointPicker to obtain the x-y-z coordinates
within my data set and then drawing a dot at those coordinates.  The
problem is that the location where the cursor is pointing, is not always
the same as the location where the dot is displayed.  It is better when
I zoom right in before picking, but would like a more "universal
solution" to my picking problem.  There have been a number of other
posting regarding Picking Accuracy, none seem to be answered.

I am using VTK4.0 and RedHat 7.1.

Sincerely

Christopher Bayley
bayley at me.queensu.ca
_______________________________________________
This is the private VTK discussion list.
Please keep messages on-topic. Check the FAQ at:
<http://public.kitware.com/cgi-bin/vtkfaq>
Follow this link to subscribe/unsubscribe:
http://public.kitware.com/mailman/listinfo/vtkusers
---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.445 / Virus Database: 250 - Release Date: 21/01/2003

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.445 / Virus Database: 250 - Release Date: 21/01/2003