[vtkusers] More info on clipping planes

[James C. Robinson]

Dear All,

I am having (more) trouble visualising a 3D FE mesh. I have it 95% working,
viewing the mesh as a vtkUnStructuredGrid. However, the problem is that, for
certain, spatially large, meshes, detail at the centre (they invariably have
a narrow cylinder running through them) can disappear as I zoom in to look
at it. This is because the default setting of the vtkInteracter is to
AutoResetClippingRange and the value of the near plane (in the method that
carries it out) has to be 10% of the far plane. This means that when viewing
a scene with some parts pf an object at 1000m from the camera, anything
closer than 100m to the camera is "clipped".

The choice is to turn this AutoResetClippingRange off and manage the
clipping planes oneself. I have almost got that to work, but I am finding
that the rendering of a vtkEdgeFeatures object that I create to view the
edges of the elements is adversely affected by changing the setting (see
attached word file). Has anybody any ideas on this?

Finally, my intuition is telling me that if my PC can handle rendering all
facets in the actor that maybe I should just set the near and far values to
say 0.1 and 10000 (assuming that my max dimension of the mesh is say 1000)
and thus all detail would be visible unless I zoom in closer than 0.1 or out
such that part of the mesh is more than 10000 from the camera. My reasoning
is that the original concern with clipping planes may have emanated from
processing worries for very complex (high numbers of facets) on slower PCs.
Is this sound reasoning?

Thanks for the attention,

Jim

______________________

James C. Robinson, PhD,
Chartered Engineer,
Kepler Engineering Software Ltd.,
42 Rivergrove, 
Glanmire, Co. Cork,
Eire

Tel:         +353-21-4822028
Tel:         +353-87-2393010
Fax:        +353-21-4822721
E-mail:     j.robinson at kepler.ie
______________________

-------------- next part --------------
A non-text attachment was scrubbed...
Name: winmail.dat
Type: application/ms-tnef
Size: 60815 bytes
Desc: not available
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20021126/7e1f7f4e/attachment.bin>