[Sidefx-houdini-list] chops and docs

Andrew D Lyons tstexture at gmail.com
Fri Feb 19 13:27:26 EST 2010


I use CHOPs constantly in procedural modelling and simulation tasks.
In the past I have used CHOPs to:

1./ Create bouncing cling wrap using the spring chop amongst others.
(cling wrap slide in "Over the Hedge")

2./ A procedural fully automated fluid system for glasses and bottles.
Uses spring CHOP to create sloshing motion.

3./ To help delete particles or points should a certain point
attribute cross a given threshold.

4./ Filter high frequency noise from ncloth simulations.

5./ As part of a fully automated foot dust system. (Detects initial
impact from proximity value.)

6./ Anything where you need to analyze a value across the full range
of animation. i,e. find min/max values, events to trigger stuff etc.
etc.

7./ When you need n (hundreds/thousands) of animation channels that
are slightly randomized - but respond to to certain scene events.

7./ Extract animation from audio etc.

My favorite CHOPs are:

geometry
noise
trigger
count
envelope
filter
shuffle
shift
function
expression

My favorite expression for channels is:
chan[0-`npoints("../../TO_CHOPs")-1`]

Which creates a channel for every point in a SOPnet.

Andrew's book will be a good help as well no doubt...

Cheers


On 19 February 2010 10:04, baq <baq8 at op.pl> wrote:
> thanks for this info, I have Cunningham's book just 2 pages about chops
> there, don't have the Lowell's one, perhaps should I buy it,
>
> I'm interested in few things, first - how people from Houdini 6 or 7(8)
> era learned chops, second how fx houses use it in production, is it
> still in use or maybe I don't know and it's a dead part of this
> software, could this knowledge(chops) be helpfull in fx animation? can I
> use it with pops?
>
>
>> This book has some stuff on chops also...
>>
>> http://www.amazon.com/Magic-Houdini-William-Michael-Cunningham/dp/1598630822/ref=sr_1_1?ie=UTF8&s=books&qid=1266595323&sr=8-1
>>
>> Dave
>>
>> 2010/2/19 François Duchesneau <sidefx at trinix.ca>
>>
>>
>>> If you have some time to invest, I suggest this book.
>>>
>>>
>>> http://www.andrew-lowell-productions.com/andrew-lowell-productions/resources.html
>>>
>>> Even if it's oriented on audio you will learn animation modulation
>>> techniques as well and the book has a ton of information.
>>>
>>> François
>>>
>>> baq wrote:
>>>
>>>> there are many parts in houdini's docs about: particles, dynamics,
>>>> animation, lighting, etc, but I don't see anything like this about chops,
>>>>
>>>> yes there are channel nodes description and that's all, all other parts
>>>> have more attention so one can know how to start to work with but not
>>>> with chops, some advnaced users say chops are so cool, powerfull, etc,
>>>> etc but yeahh just try to start with it when you just have nodes
>>>> description and don't see the whole concept, also tutorials I've found
>>>> talk about chops+audio, I don't care about audio, I know many use it for
>>>> motion, remember article also when DD said it was used by them in grinch
>>>>
>>> ...
>>>
>>>> do you hear me sesi SESI
>>>>
>>>> or anybody
>>>>
>>>>
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Andrew D Lyons | Digital Artist | http://www.tstex.com
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