[Sidefx-houdini-list] pcfilter point number

Nick Zutphen nvanzutphen at live.com
Fri Aug 5 07:07:55 EDT 2011


Hi Oleg,

I understand your reasoning, but what about setting the attribute transfer to 'max sample count' of 1 and keeping in mind that it is a native node which means its based on C++. I always figured that 'native' nodes are supposed to be faster than their equivalent in Vex, or am I unforgivably wrong?  

Cheers,
Nick van Zutphen
----
http://www.nickvanzutphen.com

On Aug 5, 2011, at 12:15 PM, Olex P wrote:

> Hi Nick,
> 
> That point cloud solution is simplest ever and most efficient (as it
> samples just 1 point). And a setup is just one VEX (or VOP if you
> want) operator. I would upload a hip file but I don't know any
> pastebin like service that supports bin files.
> 
> On Fri, Aug 5, 2011 at 10:56 AM, Nick Zutphen <nvanzutphen at live.com> wrote:
>> Hi Oleg,
>> 
>> Thank you your your reply.
>> I guess you're describing a similar approach to the one I mentioned in my first message.
>> 
>> Initially I found it a rather complicated solution which I tend to avoid, especially in VOP's, that's why I tried to use pcfilter. It turned out that  'Attribute Transfer' works perfectly in this case.
>> 
>> Cheers!
>> Nick van Zutphen
>> 
>> ----
>> http://www.nickvanzutphen.com
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> On Aug 4, 2011, at 11:35 AM, Olex P wrote:
>> 
>>> Hi guys,
>>> 
>>> Hi guys, the first entry in a point cloud lookup is always a nearest
>>> point. A following snipet of code will give you the number of nearest
>>> point and a distance to it
>>> 
>>> [code]
>>> sop
>>> pcnearest(string       pcfile  = "";
>>>                float        radius = 1.0f;
>>> 
>>>                export int   num = -1;
>>>                export float dist  = -1.0f)
>>> {
>>>    int handle = pcopen(pcfile, "P", P, radius, 1);
>>> 
>>>    if(pciterate(handle))
>>>    {
>>>        pcimport(handle, "point.number",   num);
>>>        pcimport(handle, "point.distance", dist);
>>>    }
>>> 
>>>    pcclose(handle);
>>> }
>>> [/code]
>>> 
>>> On Wed, Aug 3, 2011 at 9:14 PM, Alvaro Castaneda <varomix at gmail.com> wrote:
>>>> I think you're trying to do something more complex than it need to be
>>>> we get sometimes caught in that, but always the best thing is a simple
>>>> solution
>>>> simple to develop and simple to use.
>>>> 
>>>> Cheers
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>>  *.:varomix:.*
>>>> MIX Studio
>>>> 3D Artist/Generalist TD
>>>> www.varomix.net
>>>>  My profiles: [image: LinkedIn] <http://www.linkedin.com/in/varomix> [image:
>>>> Twitter] <http://twitter.com/varomix> [image:
>>>> Facebook]<http://www.facebook.com/varomix>
>>>> On Wed, Aug 3, 2011 at 2:00 PM, Nick van Zutphen <nvanzutphen at live.com>wrote:
>>>> 
>>>>> @ 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 <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>
>>>>>>> <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 <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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>>>>>>> 
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>>>>>>>> 
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>>>>>>>> 
>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>  ______________________________****_________________
>>>>>>> 
>>>>>>>> 
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>>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> --
>>>>>> ==============================**=========
>>>>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>>>>>> ==============================**=========
>>>>>> ______________________________**_________________
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