[Sidefx-houdini-list] Surface from image stack

François Duchesneau sidefx at trinix.ca
Thu Feb 11 17:29:58 EST 2010


You'll have to continue this thread on the forum to attach images.

Mark Bolstad wrote:
> 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
>>>>>> _______________________________________________
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>>>>>> Sidefx-houdini-list at sidefx.com
>>>>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>>>>
>>>>>>             
>>>> _______________________________________________
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>>>>
>>>>         
>>>       
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>>     
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