[Sidefx-houdini-list] vops and point clouds

François Duchesneau sidefx at trinix.ca
Thu Aug 20 08:57:32 EDT 2009


That rings a bell. I'm sure I had that issue once but I don't remember 
what it was. Are you transforming you P from current to world? Are you 
sure you've got enough max points.

François

Olex P wrote:
> Humm, I made a test but for some reason I see the clipping that you have on
> your screenshot. The rest seems to be fine.
> Have to check what exactly causes that clipping.
>
> On Thu, Aug 20, 2009 at 12:33 PM, Olex P <hoknamahn at gmail.com> wrote:
>
>   
>> Hi Nicholas,
>>
>> I believe all what you need is just go through all the points in radius and
>> sum all the values of alpha on them. The order doesn't really matter.
>>
>>
>> On Thu, Aug 20, 2009 at 11:54 AM, Nicholas Pliatsikas <
>> nick_p102 at hotmail.com> wrote:
>>
>>     
>>> Didnt realise the refract limits would affect the point cloud data. I will
>>> check into that.
>>>
>>> I had a good think about what was causing the problems last night, I think
>>> its due to how a random ID variable is working in relation to the order in
>>> which the point cloud data is being seached.
>>>
>>> For example if the current points random ID value is bigger then the
>>> random ID value of the next point it will be ignored, that point will be
>>> ignored. I guess what is really needed is some way of sorting the point
>>> datas random ID values then bring those in sequential. But I have a feeling
>>> thats not possible at all. So im trying another approach, and changing the
>>> order of where the random call is happening, i.e clipping it with the alpha
>>> map then running the if statement to check what the highest visible layer
>>> is.
>>>
>>> This is much tricker then i first thought..
>>>
>>> Cheers
>>> Nick
>>>
>>>       
>>>> Date: Wed, 19 Aug 2009 09:40:51 -0700
>>>> From: daveinengland at gmail.com
>>>> To: sidefx-houdini-list at sidefx.com
>>>> Subject: Re: [Sidefx-houdini-list] vops and point clouds
>>>>
>>>> I can't get to the files you referenced because of our firewall, but
>>>>         
>>> have
>>>       
>>>> you checked the refract limit on your objects? If this is too low, the
>>>>         
>>> rays
>>>       
>>>> will be limited by this. Also, there is the opacity limit in the ROP may
>>>>         
>>> be
>>>       
>>>> limiting your rays.
>>>>
>>>> Just a thought.
>>>>
>>>> Dave
>>>>
>>>> On Wed, Aug 19, 2009 at 2:25 AM, Nicholas Pliatsikas
>>>> <nick_p102 at hotmail.com>wrote:
>>>>
>>>>         
>>>>> Hey guys and gals.
>>>>>
>>>>> After doing a good bit of work on the point cloud shader ive hit a
>>>>>           
>>> problem.
>>>       
>>>>> To me it seems that there is some optimisations happening with the
>>>>>           
>>> point
>>>       
>>>>> cloud data or its just a bug with code/mantra .
>>>>>
>>>>> Basically when layering the point cloud circles it looks as if mantra
>>>>>           
>>> is
>>>       
>>>>> cutting out much of the underlying circles, creating a problem when
>>>>>           
>>> layering
>>>       
>>>>> images using alphas. i.e parts of the underlying images are cut off.
>>>>>
>>>>> I can't see a problem with the code i added, so I went back to the
>>>>>           
>>> example
>>>       
>>>>> Olex sent me and changed it to be additive. This illustrated the same
>>>>>           
>>> issue.
>>>       
>>>>> You can see a screen grab here
>>>>>
>>>>> https://rcpt.yousendit.com/727895459/45f82a647fbe6eae52df9dc836f604f3
>>>>>
>>>>> If it is a bug/limit with mantra I wills end this off to sidefx
>>>>>           
>>> support.
>>>       
>>>>> I have also saved out the additive version of the hipfile, you can
>>>>>           
>>> download
>>>       
>>>>> it here.
>>>>>
>>>>> https://rcpt.yousendit.com/727894133/de680b2c71c2c8d61f6dc0700d9d57a4
>>>>>
>>>>> I hope this is something we can get around as it will be a really nice
>>>>>           
>>> way
>>>       
>>>>> to add controlled details to scene. Just a note it also seems as if
>>>>>           
>>> there is
>>>       
>>>>> the odd point radius that isnt being added correctly either (the green
>>>>> circles at the bottom right of the screen for example)
>>>>>
>>>>> Cheers
>>>>> Nick
>>>>>
>>>>>           
>>>>>> From: nick_p102 at hotmail.com
>>>>>> To: sidefx-houdini-list at sidefx.com
>>>>>> Date: Fri, 14 Aug 2009 15:55:02 +0000
>>>>>> Subject: Re: [Sidefx-houdini-list] vops and point clouds
>>>>>>
>>>>>>
>>>>>> Thanks for that Olex :) thats a great example, I see what you where
>>>>>>             
>>>>> meaning in your code about using the maxheight random calls. Just
>>>>>           
>>> trying
>>>       
>>>>> this out in vops, having some oddities but will try a few more times
>>>>>           
>>> until i
>>>       
>>>>> resort to vex coding ;¬) as i need to quite abit inside that loop.
>>>>>           
>>>>>> Cheers mucho!!!
>>>>>> Nick
>>>>>>
>>>>>>
>>>>>>
>>>>>>             
>>>>>>> Date: Fri, 14 Aug 2009 13:46:49 +0100
>>>>>>> From: hoknamahn at gmail.com
>>>>>>> To: sidefx-houdini-list at sidefx.com
>>>>>>> Subject: Re: [Sidefx-houdini-list] vops and point clouds
>>>>>>>
>>>>>>> Oops, that was toooo quick test. There is correct one
>>>>>>>
>>>>>>>
>>>>>>>               
>>> http://www.hotmail.ru/download.php/?file=:pcdvd2.hip&host=alex-hawk.hotmail.ru/flashcard&user=alex-hawk&lng=ru
>>>       
>>>>>>> On Fri, Aug 14, 2009 at 1:33 PM, Olex P <hoknamahn at gmail.com>
>>>>>>>               
>>> wrote:
>>>       
>>>>>>>> Hey,
>>>>>>>>
>>>>>>>> There is a quick example
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>                 
>>> http://www.hotmail.ru/download.php/?file=:pcdvd.hip&host=alex-hawk.hotmail.ru/flashcard&user=alex-hawk&lng=ru
>>>       
>>>>>>>> AA isn't included! :p
>>>>>>>>
>>>>>>>>
>>>>>>>> On Fri, Aug 14, 2009 at 12:24 PM, <eetu at iki.fi> wrote:
>>>>>>>>
>>>>>>>>                 
>>>>>>>>>>>>> Hey Peoples
>>>>>>>>>>>>>
>>>>>>>>>>>>> Im currently working on an image bombing point cloud
>>>>>>>>>>>>>                           
>>> shader
>>>       
>>>>> and hit
>>>>>           
>>>>>>>>> a
>>>>>>>>>                   
>>>>>>>>>>>>> problem i dont quite understand how to solve.
>>>>>>>>>>>>>                           
>>>>>>>>> Here's a thread from Georg which might well be relevant for you
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>                   
>>> http://forums.odforce.net/index.php?/topic/6967-a-shader-each-day/page__view__findpost__p__47148
>>>       
>>>>>>>>> I vaguely remember another forum thread with someone battling
>>>>>>>>>                   
>>> with
>>>       
>>>>> the
>>>>>           
>>>>>>>>> same problem, but can't find it now for the life of me. I think
>>>>>>>>>                   
>>> it
>>>       
>>>>> was
>>>>>           
>>>>>>>>> about overlapping fakeshadow blobs, if you happen to be able to
>>>>>>>>>                   
>>> find
>>>       
>>>>> it :)
>>>>>           
>>>>>>>>> eetu.
>>>>>>>>>
>>>>>>>>>
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>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>       
>>>>>>>>                 
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