[MINC-users] How to create a "wireframe" surface object?

[Alexandre CARMEL-VEILLEUX]

On Tue, Jun 26, 2007 at 11:42:01AM -0400, Najmeh Khalili M. wrote:
> 
> Can you please tell me where/what -one_hit is/does?

	The ray will only hit once on the same object. So if a ray
would have say, gone through a sulcus and out and then back into another
one again, ray_trace will not render both surfaces if they're part of the
same .obj (I only used .obj with a single object in them I have no idea
how it would behave with multiple disconnected surfaces in a single .obj
file.)

	This is only an issue if the surface is not opaque obviously.
However with -one_hit ray_trace will render the surface of the first hit
on every different objects it encounters, like your markers.

	It's best to experiment with this.

	I hope I make sense ;-)

Alex

> 
> Yes, semi-opaque surfaces look better than grid ones.
> 
> Best
> Naj
> 
> On Tue, 26 Jun 2007, Alexandre CARMEL-VEILLEUX wrote:
> 
> > On Tue, Jun 26, 2007 at 09:49:01AM -0400, Najmeh Khalili M. wrote:
> > >
> > > I couldn't get the tags_to_spheres produce pretty markers, but
> > > reducing the surface opacity allowed me to ray_trace subcortical
> > > objects.
> > >
> > > The plygons_to_lines works well. (Is there a way to subsample
> > > the polygons? I tried "smooth_lines" on the polygon.obj,
> > > but it doesn't seem to change anything. I tried it with
> > > distance 0.2 and 100!!)
> >
> > Couple of things about ray_trace:
> >
> > 	* It can't render well meshes that contain anything but
> > 	  triangles. There's a command to convert polygons to
> > 	  triangles to do that. (Something like triangulate_polygons
> > 	  from memory but I'd have to check.)
> >
> > 	* -one_hit tends to produce nicer looks with semi-opaque
> > 	  surfaces. The effect may or may not be desirable to you.
> >
> > 	* ray_trace has tons of undocumented switches such as
> > 	  -marker_sphere, -marker_size, -marker_colour and so on.
> >
> > 	* Dave MacDonald's tutorial is fairly good (but incomplete):
> > 	  http://www.bic.mni.mcgill.ca/~david/Ray_trace/ray_trace_tutorial.html
> >
> > Alex
> >
> > >
> > > Cheers
> > > Naj
> > >
> > > On Tue, 26 Jun 2007, [ISO-8859-1] Lasse Riis Østergaard wrote:
> > >
> > > > I don't think ray_trace allows wireframe rendering. Instead you can do
> > > > the following:
> > > >
> > > > Step 1 - polygons_to_lines polygon.obj poly_lines.obj
> > > > Step 2 - ray_trace -output image.rgb poly_lines.obj -bg white -size 350
> > > > 350 -top -crop
> > > >
> > > > Lasse
> > > >
> > > > Najmeh Khalili M. wrote:
> > > > > Hi, I need to generate a surface object in order to use it with
> > > > > ray_trace. As I am interested in showing subcortical markers, I
> > > > > need the object file to be semi-transparent, preferably with
> > > > > wireframe representation.
> > > > >
> > > > > I'd appreciate any suggestions.
> > > > > Naj
> > > > >
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> > >
> >
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> 
> 
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