[Sidefx-houdini-list] Surface from image stack

Mark Bolstad the.render.dude at gmail.com
Thu Feb 11 17:27:03 EST 2010


Thanks for the ideas.

If the list will allow me to attach images, I'll append 3 images that are
representative of consecutive levels. This one has a bifurcation on level
two.

Mark


2010/2/11 François Duchesneau <sidefx at trinix.ca>

> That reminds me a tool I created to mimick Blast Code. In Blast Code you
> could use a bad quality crack pattern found on the web with varying line
> thickness. The tool I created used the Trace Sop internally but had to
> do lots of Sop operation to make it work. However, it was very picky
> about the line width. I'd be curious to know what is the algorithm Blast
> Code uses because it looks more like something giving the center of the
> line only, like you want. That little improvement on the Trace Sop would
> be great.
>
> François
>
> Michael K. O'Brien wrote:
> > Hola~
> >
> >
> >> -- On Thu, Feb 11, 2010 at 04:29:58PM -0500, Jerry wrote:
> >> Check the second tab on the trace SOP.
> >>
> >
> > I tried that, but without any luck. I'll give it another go.
> >
> > My sample image is 16x16, all black, white horiz line in the middle. I
> end up
> > with with a closed curve that encircles all of the pixels.
> >
> > I ended up writing a medial axis node, which is really slow, but seems to
> be a
> > bit closer to what I would expect.
> >
> > MO
> >
> >
> >>> Hola~
> >>>
> >>>
> >>>> -- On Thu, Feb 11, 2010 at 03:19:05PM -0500, Mark Elendt wrote:
> >>>> On Thursday Feb 11 at 14:46, Mark Bolstad wrote:
> >>>>
> >>>>> I have a stack of black and white images that consist of a set of
> >>>>> disconnected circle like shapes. First, how do you extract the
> >>>>>
> >>>> boundary
> >>>>
> >>>>> curve(s) and pass them to a SOP?
> >>>>>
> >>>>> Second, given a set of these extracted curves, I need to join them
> >>>>>
> >>>> into a
> >>>>
> >>>>> surface (assume some fixed offset between the curves). The problem is
> >>>>>
> >>>> that
> >>>>
> >>>>> in some cases I'll have two curves on one level and 1 curve on the
> >>>>>
> >>>> next
> >>>>
> >>>>> level (the actual data is bifurcating somewhere in between the
> >>>>>
> >>>> levels).
> >>>>
> >>>>> The application is reconstructing neurons from a set of electron
> >>>>>
> >>>> microscopy
> >>>>
> >>>>> images.
> >>>>>
> >>>>> Any help is appreciated.
> >>>>>
> >>>> Could you make a volume (even an i3d file)?
> >>>> The ISO SOP with an inside/out expression?
> >>>>
> >>>> If the topology changes (i.e. you have two circles blending to one),
> >>>> that could be problematic.
> >>>>
> >>>> If you are guaranteed to have only one circle, then use the trace SOP
> >>>> and poly loft (or poly spline and skin).
> >>>>
> >>> Is there a way to get a true curve out of trace? Trace wants to
> surround
> >>> each
> >>> pixel with a poly face, as opposed to generating a curve that connects
> >>> the
> >>> pixels above the threshold, right?
> >>>
> >>> MO
> >>>
> >>>
> >>>> --
> >>>> Mark Elendt
> >>>> _______________________________________________
> >>>> Sidefx-houdini-list mailing list
> >>>> Sidefx-houdini-list at sidefx.com
> >>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>
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> >>
> >
> >
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