I've made a second attempt at creating realistic Potato-Chips.
https://vimeo.com/76864119 [vimeo.com]
The mayor innovation in this version is my layered noise .otl, that works in the SHOP and SOP context joined by a preview node for easy previewing and isolating individual layers for tweaking. It allows one to layer 3 different layers of noise, have float and vector outputs, apply various operations to combine the layers and offset the noise patterns by an id input.
I've introduced the idea of a float id attribute, where the rounded number and the fraction can be handled differently. For instance, the whole number can be constant per object or piece, where the float value can be different on a per point basis with only minor differences, allowing for a wide range of artistic control.
I'm using different sets of layered noise for channels like diffuse, spec, displacement and refraction. Part of the trick is to have some sets that share similar patterns. For instance the larger displacement pattern (single layer) is also used to drive the base layer of the diffuse. To get the snowy peaks idea, but then topped up with two different layers to make it look more natural.
I never used the exact same patterns to drive different channels of the shader, people are really good at spotting patterns.
Another feature of the potato-chips shader is that it takes a ‘edge’ attribute, basically an attribute that has a 0-1 value from the center to the edge. This allows to scale down displacements that are closer to the edge, add burned edges and that sort of stuff.
I found that per piece random slight color offsets help to sell the shot as well. It makes it easier to believe they are real.
Apart from that it was a tremendous amount of testing, I found it so difficult to get the right look. In the process I've created a ton of pringles, those are easy ;-).
The pieces don't feature the ‘popped bell’ things, because
A I couldn't get it right on a procedural basis (probably need to create hero pieces for that)
B. This is aimed at clients in the television commercial business and I don't think Lays wants any of these things in its commercials.
You can find a detailed article (though aimed on potential clients) on my website: www.nicknimble.com/index.php?option=com_content&view=article&id=129%3Acgi-potato-chips-attempt-2&catid=40%3Atechnical-achievements&Itemid=55&lang=en [nicknimble.com]
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Work in Progress » CGI Potato Chips | attempt 2
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- houdinick
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The Orbolt Smart 3D Asset Store » Holiday Challenge; get a card on!
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chrism
http://www.youtube.com/watch?feature=player_embedded&v=NS6HEe4LavM [youtube.com]houdinick
Cool :-)
The blue package must contain something very special, it seems to be hoovering! I'm sorry martin, I couldn't resist :p

The Orbolt Smart 3D Asset Store » Holiday Challenge; get a card on!
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- houdinick
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Cool :-)
The blue package must contain something very special, it seems to be hoovering! I'm sorry martin, I couldn't resist :p
The blue package must contain something very special, it seems to be hoovering! I'm sorry martin, I couldn't resist :p
Houdini Lounge » Docs 12.1 down?
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- houdinick
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Technical Discussion » Definitive method for FLIP retimeing
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- houdinick
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Hi SYmek, I just had a look at the ‘barycentric rational’ paper I found on Google. Are you implying you understand this!? Any chance you could explain it in Human? ;-)
http://www.google.nl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CEwQFjAD&url=http%3A%2F%2Fcg.in.tu-clausthal.de%2Fpapers%2Fhormann%2FDarmstadt.2006.pdf&ei=P1y2UKX3B4HM0AXcq4HgAw&usg=AFQjCNG6bskgV7ITvjcIAcIbEt0Lf-iIkw [google.nl]
http://www.google.nl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CEwQFjAD&url=http%3A%2F%2Fcg.in.tu-clausthal.de%2Fpapers%2Fhormann%2FDarmstadt.2006.pdf&ei=P1y2UKX3B4HM0AXcq4HgAw&usg=AFQjCNG6bskgV7ITvjcIAcIbEt0Lf-iIkw [google.nl]
Technical Discussion » Definitive method for FLIP retimeing
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- houdinick
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I assume you used linear interpolation right? Did you ever noticed the angular steps when a particle passes a ‘key’ frame and suddenly moves in a different direction?
Technical Discussion » Definitive method for FLIP retimeing
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- houdinick
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I can confirm that retiming particles with CHOPs and using the id attribute works. We only need to figure out something smart to solve the problem of the birth and death of particles. The channel SOP seems to like static geometry that it can ‘deform’ based on a CHOP curve.
From the top of my head, maybe analyze the particles with a Solver SOP, and recreate new points when its corresponding particle is born with corresponding ID's and position frozen in space and remove them when the original point died keeping for the birth and dead the timewarp in mind.
Sounds like a python SOP, Solver SOP and some additional CHOP channels?
It would be so cool if you could sim FLIP particles at 24FPS and timewarp them to 1000FPS, with a speed ramp and all :-D
From the top of my head, maybe analyze the particles with a Solver SOP, and recreate new points when its corresponding particle is born with corresponding ID's and position frozen in space and remove them when the original point died keeping for the birth and dead the timewarp in mind.
Sounds like a python SOP, Solver SOP and some additional CHOP channels?
It would be so cool if you could sim FLIP particles at 24FPS and timewarp them to 1000FPS, with a speed ramp and all :-D
Technical Discussion » Definitive method for FLIP retimeing
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- houdinick
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That is what I have been thinking of since I created this topic. Though I haven't tested if CHOPS can create curves based on ID's instead of point numbers. Let alone how CHOPS behaves when it has to deal with 5 million curves.
I sense it starts with writing out a .clip file and not opening a motion view or curve editor ;-).
Has any one any experience with large number of curves and particle ID's in CHOPS?
I sense it starts with writing out a .clip file and not opening a motion view or curve editor ;-).
Has any one any experience with large number of curves and particle ID's in CHOPS?
Technical Discussion » Definitive method for FLIP retimeing
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- houdinick
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Hi,
I wonder, what would be the best way to timewarp a FLIP fluid simulation? I'm talking about going from realtime (24fps) to say slowmotion (1000fps) and back.
In real life they shoot at 1000fps and do a post timewarp. In simulation land this is quite painful because it takes an awful long time and you throw away a lot.
Ideally I would like to be able to animate something like the timescale attribute on the DOP network. This way you only simulate what you eventually need. How ever this parameter is not ‘animatable’.
You might argue that this is more difficult to tweak because one needs to resim and wish one could do a post timewarp, but I think in the end its the fasted/most detailed method.
With less extreme examples you might be able to do some trickery in SOP's, but this will always be a linear interpolation and you lose the non-diversion property during the in-between frames.
What about .sim files, is there anything we can do with that?
Would it be an option to build a FLIP retime solver which uses an existing FLIP sim (at real time) written out as a .sim seq?
I wonder, what would be the best way to timewarp a FLIP fluid simulation? I'm talking about going from realtime (24fps) to say slowmotion (1000fps) and back.
In real life they shoot at 1000fps and do a post timewarp. In simulation land this is quite painful because it takes an awful long time and you throw away a lot.
Ideally I would like to be able to animate something like the timescale attribute on the DOP network. This way you only simulate what you eventually need. How ever this parameter is not ‘animatable’.
You might argue that this is more difficult to tweak because one needs to resim and wish one could do a post timewarp, but I think in the end its the fasted/most detailed method.
With less extreme examples you might be able to do some trickery in SOP's, but this will always be a linear interpolation and you lose the non-diversion property during the in-between frames.
What about .sim files, is there anything we can do with that?
Would it be an option to build a FLIP retime solver which uses an existing FLIP sim (at real time) written out as a .sim seq?
Houdini Lounge » Docs 12.1 down?
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- houdinick
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Hi,
Just want to make a note that when I go to http://www.sidefx.com/docs/houdini12.1/ [sidefx.com] I'm presented with ‘Index of /docs/houdini12.1’ and a list of folders instead of the help ‘website’.
Just want to make a note that when I go to http://www.sidefx.com/docs/houdini12.1/ [sidefx.com] I'm presented with ‘Index of /docs/houdini12.1’ and a list of folders instead of the help ‘website’.
Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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The workaround that I found is to switch from Gnome-Unity (the default) to ‘Gnome 3 Classic’ or ‘Gnome 3 fallback’. It still annoys me that I can't get it to work in Unity, but…
Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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Yet another clever solution :-)
Unfortunately it doesn't help in my particular case :-(
If I compare it to how Houdini runs on my Macbook Pro, the mouse pointer is different, which would suggest that Houdini knows that drag and drop doesn't work.
Which leaves me wondering how to solve this. I sense its a ubuntu problem.
Unfortunately it doesn't help in my particular case :-(
If I compare it to how Houdini runs on my Macbook Pro, the mouse pointer is different, which would suggest that Houdini knows that drag and drop doesn't work.
Which leaves me wondering how to solve this. I sense its a ubuntu problem.
Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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Hi Coen,
Good one, that didn't came to mind. Unfortunately it didn't work…
Its a new install of Ubuntu 12.04 and it has been like this from the start.
SESI develops on Ubuntu, so I figured that they should have run into this problem already.
Good one, that didn't came to mind. Unfortunately it didn't work…
Its a new install of Ubuntu 12.04 and it has been like this from the start.
SESI develops on Ubuntu, so I figured that they should have run into this problem already.
Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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That sounds like the other untraceable bug where Houdini confuses the window order.
Unfortunately resizing the main window doesn't work in my case. I can never drag and drop. I do have to add that for instance when I drag a shader in the viewport on a object, then I see a cursor that has a pointer a dotted box and a circle with diagonal line aka ‘not permitted’.
Unfortunately resizing the main window doesn't work in my case. I can never drag and drop. I do have to add that for instance when I drag a shader in the viewport on a object, then I see a cursor that has a pointer a dotted box and a circle with diagonal line aka ‘not permitted’.
Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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I haven't fixed it yet, how ever I've found the gconf-editor which might be part of the solution. Does anyone know which option is causing the drag and drop issues in Houdini?
Tip:
If you go in gconf-editor to apps/metacity/general and type ‘sloppy’ in the focus_mode, you get auto focus, which is nice if you happen to have a multi monitor setup.
Tip:
If you go in gconf-editor to apps/metacity/general and type ‘sloppy’ in the focus_mode, you get auto focus, which is nice if you happen to have a multi monitor setup.
Technical Discussion » Ubuntu 12.04 - Drag and drop doesn't work
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- houdinick
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Hi
I know this has been asked before, but I can't get it to work.
I run Houdini on Ubuntu 12.04 with Unity enabled. Within Houdini I'm not able to drag and drop parameters or rearange parameters in a digital asset. It seems quite clear that something is capturing the ‘ hold left mouse button’ action.
The question remains how do I make it stop doing so. I really like Unity and I wonder if someone has mananged to get it to work with Houdini?
I know this has been asked before, but I can't get it to work.
I run Houdini on Ubuntu 12.04 with Unity enabled. Within Houdini I'm not able to drag and drop parameters or rearange parameters in a digital asset. It seems quite clear that something is capturing the ‘ hold left mouse button’ action.
The question remains how do I make it stop doing so. I really like Unity and I wonder if someone has mananged to get it to work with Houdini?
Technical Discussion » Attribute precedence incorrect?
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- houdinick
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tamte
the question is why someone felt that vertex and point attribute of the same name shouldn't be present at the same time? There is a rule that in that case Vertex attributes have priority in render so I see no reason not having them there if I need both, it would be nice if this automatic removal process was not happening, RFE maybe?
Jup, I agree. Without auto delete procedures should it be just as plain as:
Vertex overrides point
Point overrides Primitive
Primitive overrides Detail
Technical Discussion » Attribute precedence incorrect?
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- houdinick
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Ah ha! I didn't notice that. I'll pay more attention next time.
Thank you mark :-).
I don't encourage the idea of having multiple attributes of different classes with the same name on geometry. But I'm researching the topic of attributes for a future in-depth houdini class I'm going to teach.
The rule for matching attributes of different classes is:
Vertex overrides point
Point overrides Primitive
Primitive overrides Detail
but the exception is:
Vertex and Point attributes with the same name are not allowed to reside next to each other on the geometry, so the creation of the latter clears the existing one.
Thank you mark :-).
I don't encourage the idea of having multiple attributes of different classes with the same name on geometry. But I'm researching the topic of attributes for a future in-depth houdini class I'm going to teach.
The rule for matching attributes of different classes is:
Vertex overrides point
Point overrides Primitive
Primitive overrides Detail
but the exception is:
Vertex and Point attributes with the same name are not allowed to reside next to each other on the geometry, so the creation of the latter clears the existing one.
Technical Discussion » Attribute precedence incorrect?
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- houdinick
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According to help page: http://www.sidefx.com/docs/houdini12.0/model/attributes [sidefx.com]
When two components in the same geometry have an attribute with the same name, the attribute on the lower level of geometry is used, so:
Vertex overrides point
Point overrides Primitive
Primitive overrides Detail
How ever in the attached example Vertex overrides Point and Point overrides Vertex.
Is this the expected behaviour?
When two components in the same geometry have an attribute with the same name, the attribute on the lower level of geometry is used, so:
Vertex overrides point
Point overrides Primitive
Primitive overrides Detail
How ever in the attached example Vertex overrides Point and Point overrides Vertex.
Is this the expected behaviour?
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