[Sidefx-houdini-list] pcfilter point number

Nick van Zutphen nvanzutphen at live.com
Wed Aug 3 16:00:09 EDT 2011


@ Andrew
Ghehe, well with all due respect but your solution, compared to what I was 
doing, is almost ridiculous due to its simplicity. But I like it! :-). It 
works perfectly. Thanks a lot.

@Mike
I have to keep this in mind because I'm pretty sure I'll run in to this one 
again. Pcfilter works perfect if you would like to get position of 1 or 
especially an average of multiple points, to bad it doesn't do the trick in 
this case. Thank you for your input, it's much appreciated. Though Andrews 
solution is, in this particular case, the way to go.

Case closed, (with that paper file and red 'case closed' stamp on it ;-)
Nick van Zutphen
--------------------------------------------------
From: "Andrew Lyons" <tstexture at gmail.com>
Sent: Wednesday, August 03, 2011 9:12 PM
To: <sidefx-houdini-list at sidefx.com>
Subject: Re: [Sidefx-houdini-list] pcfilter point number

> Not totally clear on the problem - but I've always used the attribTransfer
> SOP to get near points:
>
> 1./ Create custom point "ptnum" int attr. Store $PT in there.
> 2./ attrTransfer ptnum to new geometry. (Set "Max Sample Count" set to 2 
> if
> feeding same SOP into both inputs. Set to 1 otherwise.)
>
> Cheers
>
> On 3 August 2011 11:32, <mdunkley at gmail.com> wrote:
>
>> Hey Nick -
>>
>> I've had some fiddly problems using pcfilter for point numbers in the 
>> past.
>> I was attempting to create a float point number variable called ptnum and
>> just look it up with no interpolation (ie 1 point lookup) from pcfilter, 
>> but
>> even then i would often get incorrect values - I think the filter is 
>> doing
>> some kind of filtering no matter what. Sometimes the ptnum value it 
>> returned
>> would just be a number off, as if it was getting ceil'ed or floor'ed, 
>> some
>> times it came back with a floating point component, so clearly there was
>> some sort of interpolation happening.
>>
>> I can say for sure that the other method you mentioned *does* work.
>> Pciterate doesn't really do anything on its own - you need it to feed a
>> while loop (both ouside the loop, and then again on the inside). Within 
>> the
>> while, you can then use pcimport with "point.number" / "point.distance" 
>> to
>> pull all that info out. My impression of pcfilter is that its just a 
>> quick
>> and dirty one-stop-shop way to slew values between points, not to 
>> intended
>> to work with the other point cloud functions - if you need to do anything
>> very specific you'll have to roll your own with pciterate and a while 
>> loop.
>>
>> If you haven't seen it, check out peter quint's point cloud videos on 
>> vimeo
>> - the second one talks very specifically about some of the issues related 
>> to
>> making your own:
>> http://vimeo.com/9108284
>>
>> Best,
>> Mike
>>
>>
>>
>> On , Nick van Zutphen <nvanzutphen at live.com> wrote:
>>
>>> I like to stay close to 'SESI' guidelines, or like the default tools 
>>> work
>>> (something I inherited from my intenship). I guess giving a position 
>>> vector,
>>> which can also be set by using a handle is pretty close to that. 
>>> Obviously
>>> using a sphere would work, but it's not very neat, is it?
>>>
>>
>>
>>
>>  Cheers,
>>>
>>
>>  Nick van Zutphen
>>>
>>
>>
>>
>>  ------------------------------**--------------------
>>>
>>
>>  From: "Alvaro Castaneda" varomix at gmail.com>
>>>
>>
>>  Sent: Wednesday, August 03, 2011 6:21 PM
>>>
>>
>>  To: sidefx-houdini-list at sidefx.com**>
>>>
>>
>>  Subject: Re: [Sidefx-houdini-list] pcfilter point number
>>>
>>
>>
>>
>>
>>  This might be a dumb idea, but why don't you
>>>
>>
>>  ask the user to place a sphere for initial position
>>>
>>
>>  use that to grab any points inside and start from there?
>>>
>>
>>
>>
>>  I can use that :)
>>>
>>
>>
>>
>>
>>
>>
>>
>>  
>>>
>>
>>
>>
>>  *.:varomix:.*
>>>
>>
>>  MIX Studio
>>>
>>
>>  3D Artist/Generalist TD
>>>
>>
>>  www.varomix.net
>>>
>>
>>  My profiles: [image: LinkedIn] 
>> http://www.linkedin.com/in/**varomix<http://www.linkedin.com/in/varomix>>
>>> [image:
>>>
>>
>>  Twitter] http://twitter.com/varomix> [image:
>>>
>>
>> 
>> Facebook]http://www.facebook.**com/varomix<http://www.facebook.com/varomix>
>>> >
>>>
>>
>>  On Wed, Aug 3, 2011 at 10:06 AM, Nick van Zutphen nvanzutphen at live.com
>>> >wrote:
>>>
>>
>>
>>
>>
>>  Hi!
>>>
>>
>>
>>
>>  I finally figured out how this maillist thing works :-), at least I hope
>>>
>>
>>  so. It feels a bit like 'you're used to Internet, and you have to use 
>> 'the
>>>
>>
>>  wire', telex or how ever it's called in English' ;-).
>>>
>>
>>
>>
>>  I'm working on a tool which operates on scattered points and it needs a
>>>
>>
>>  starting point. I would like to give the user the ability to specify a
>>>
>>
>>  position vector and the tool will figure out what the closest point is.
>>> This
>>>
>>
>>  becomes need when you would like to start in a certain area and the 
>> points
>>>
>>
>>  might change due to a different seed or what so ever.
>>>
>>
>>
>>
>>  I think of a pointcloud method, however I'm interested in the closest
>>> point
>>>
>>
>>  pointnumber. I know pciterate has the option point.number but that 
>> doesn't
>>>
>>
>>  seem to work on pcfilter and ptnum doesn't give any luck either. I would
>>>
>>
>>  like to use pcfilter since it's about a single point and iterating over 
>> 1
>>>
>>
>>  point doesn't seem to make much sense.
>>>
>>
>>
>>
>>  So my question is: 'Is there a way to get the point number when using
>>>
>>
>>  pcfilter. If not, what's the alternative?'
>>>
>>
>>
>>
>>  Cheers!
>>>
>>
>>  Nick van Zutphen
>>>
>>
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>
>
>
> -- 
> =======================================
> Andrew D Lyons | Digital Artist | http://www.tstex.com
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