[Sidefx-houdini-list] vops and point clouds

Nicholas Pliatsikas nick_p102 at hotmail.com
Fri Aug 14 06:53:42 EDT 2009


Cheers for these tips :¬)
 
Soft falloff isnt really the issue as i need a clean "circle"(point radius) of UV data, that allows me to map my images onto the correct uv coord.

Theres no height diffrence between the points hieght either as they could be on a flat surface. 

Heres a more real life example of what i want todo, imagine throwing a bunch of dvd discs on the floor and taking a photo from above. Thats basically what I want to replicate with the shader except my images will have custom alphas.

We have this set up working with the pcfilter method ( but its limited due how the point radius merge together of course ) So my idea was to use the while loop pcIterate method to allow me to layer my results as i need.

Its tricky :¬/ maybe i have hit a bug with the intersections.
Thanks
Nick

> Date: Fri, 14 Aug 2009 21:34:15 +1100
> From: louisdunlevy at gmail.com
> To: sidefx-houdini-list at sidefx.com
> Subject: Re: [Sidefx-houdini-list] vops and point clouds
> 
> Usually in a pciterate loop you have to roll your own soft falloff to
> the edge of the sample radius. If you have a look at the VEX help on
> pcfilter it explains it very well with a nice example!
> 
> Hope that helps?
> L
> 
> Olex P wrote:
> > First step is to think about rules for layering. For instance if layering
> > based on the height of the circle's center (it can be Y component of
> > coordinate) and you want to render higher circles on top of lower ones you
> > can create "max" filter (precisely max(y)) and use attributes from highest
> > circle.
> >
> > Hope it makes sense.
> >
> > On Fri, Aug 14, 2009 at 10:48 AM, Nicholas Pliatsikas <nick_p102 at hotmail.com
> >   
> >> wrote:
> >>     
> >
> >   
> >> Hey Peoples
> >>
> >> Im currently working on an image bombing point cloud shader and hit a
> >> problem i dont quite understand how to solve.
> >>
> >> Im trying to grab individual points information using pcOpen and a while
> >> loop with a pciterate vop. By scanning for more then 1 point I can gather
> >> all information i need to add the point data together, which is good for
> >> other uses.
> >>
> >> My problem is this part of the shader requires the ability to layer point
> >> information ontop of each other. For example using the composite vop node,
> >> and layering A on over B. i.e the current point data over the current total
> >> point data . Essentially creating circles layered over circles.
> >>
> >> I found using the pcOpen/pciterate method doesnt layer as I expect, and I
> >> end up with circles "intersecting" rather then layering cleanly. Anybody any
> >> ideas on why this is happening and if it is possible to solve?
> >>
> >> Cheers
> >> Nick
> >>
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