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Hi All,
I am using the new plastic deformation tools in the cloth object in DOPS. I have a helicopter tail that gets ripped off from the body of the copter and smashes into the ground denting as it hits things. Because cloth is topology based, I stripped the tail down to the most basic section that needs to dent. I have my tail ripping and denting properly but now I need to add BACK on the complicated end piece with the rotor and the little rear wing/fin thing.
Attached is a pic of the helicopter - http://www.saigon-gpdaily.com.vn/dataimages/original/images148998_copter.jpg
again - considering just the tail portion - the tube part is a dented cloth object stripped of the rear wings and big circle rotor stuff. I don't need to dent either of those but I need them to be RBD objects in the same sim.
Basically, because the initial motion is based off the tail splitting, I need to get the other pieces to follow it - BUT it's possible as everything falls, the rear area will hit first so as far as I can see everything has to stay in the same sim.
I tried using RBD pin constraints but can only attach them to the object as a whole or to a location in world space - I can't figure out how to get it to work off specific points on the object. The SBD constraint tools would allow me to pick a specific point, but the monster rotor piece is too complex to turn into a cloth object just for the sake of pinning/parenting.
Most of the help docs are concerned with pinning wires and soft bodies to rigid bodies, but i'm having a difficult time finding some way to swap that and have the RBD objects follow the dented object.
I haven't checked out the DOPS grouping options - but more because I haven't found any good examples of how to use them. The rivet obj seems to be object based although maybe I can pipe those into dops to use as constraints?
Thanks for any suggestions,
Erika
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Hello all, I am hoping that someone out there will be able to help me solve my problem. I am trying to do the reverse of a disintegration effect, but have racked my brain for every possible solution. As most have seen sand vase disintegration by Miguel (odforce.net), I am trying to do the complete opposite. I am trying to have points start out sporadically and based on a mask going across the geometry, integrate (or come together on the surface of the geo) and stay. What is the best possible way of accomplishing this effect? My closest trials have been creating the simulation that I want, in reverse. Bake the particles out, batch rename the baked particle files so that they are running backwards when I pull them back into Houdini. This strategy hasn't been that successful, but it's the closest I've gotten. The problem with this strategy is that I can't use a RenderPOP to render my particles, because they are at the GEO level (once pulled back in), not
the POP level. I also don't have any control over the particles once baked out. Time remapping the simulation in post won't work either, because I have camera movements that need match. Attached is the disintegrating vase that I'm using for reference. Any and all help would be greatly appreciated. I know that this is kind of confusing, but I don't know how else to explain it. Hope this makes sense. Thanks Again,
Stephen
sjones at thedvigroup.com Any hip files would be most helpful as I am still trying to learn all of the ins and outs of Houdini.
again I was wrong about the usage of divergence and curl in fluid dynamics,
it seems that, divergence is a scalar field which is generated from a vector
field like velocity but it is not limited with velocity, it measures how
much the vectors are converging or diverging at any point, and curl is the
rotation of a vector field around a point and it is another vector field.
As the Navier-Strokes equations states (especially the incompressibility
equation) the divergence of the velocity field should be zero. So I've read
some articles where they are updating particle positions and velocities so
that the divergence be zero and the total volume of the fluid is preserved
while having a nice fluid. On the other hand, the Fusion CI guys are filling
new particles in high divergent points which leads a fluid with more volume.
But I think they don't care about it, because it is visually more
satisfactory.
an some good news, I was going to try to create nodes to let me calculate
the divergence, but hopefully there is a node among micro solvers called
"Gas Analysis" which does the divergence calculation among the other things.
So I'm on my way...
E.Ozgur Yilmaz
Lead Technical Director
www.ozgurfx.com
On Sun, Apr 18, 2010 at 8:23 PM, Ozgur Y?lmaz <eoyilmaz at gmail.com> wrote:
> sorry I was wrong about vorticity. It is the divergence and curl of the
> velocity field that you use as parameters while modelling a fluid flow.
> Vorticity is another concept that happens in boundaries of viscous fluids
> when the fluid is in touch with a solid material.
>
>
> E.Ozgur Yilmaz
> Lead Technical Director
> www.ozgurfx.com
>
>
> On Sun, Apr 18, 2010 at 11:02 AM, Ozgur Y?lmaz <eoyilmaz at gmail.com> wrote:
>
>> Pablo, if you can download the videos in their site, you can actually see
>> the thin layer of particles that they are talking about. So it doesn't seem
>> to me like that they are doing some trick in surfacing phase, but instead
>> they are filling new particles in specific places, specifically the places
>> where the holes are going to form.
>>
>> As they have explained in the interview, this places where a hole is going
>> to form actually can be found by calculating the divergences of the
>> particles. I haven't tested this idea though, so I'm sure there are some
>> other things that they keep as a secret.
>>
>> I've generated particles where the density gets lower a threshold, but as
>> the Fusion CI guys said there are sudden explosions when you do something
>> like that. So you also need to keep track of the inner pressure to prevent
>> explosions in the simulation.
>>
>> So the whole idea should be something like that, calculate each particles
>> divergence, and if the divergence goes below a threshold (may be negative
>> divergence is enough, I need to check it), then check the pressure at that
>> position and if the pressure goes also below a threshold emit a new particle
>> at this position, and may inherit the attributes from the neighbour
>> particles ( again I haven't tested anything). Though, these are bare ideas,
>> this Monday I'm going to look at these ideas, when I get back to work.
>>
>>
>> Cheers.
>>
>> E.Ozgur Yilmaz
>> Lead Technical Director
>> www.ozgurfx.com
>>
>>
>> 2010/4/18 Pablo Gim?nez <pablogipi at gmail.com>
>>
>> I remembered this article about Smorganic.
>>> After reading it and having done some similar work before in Houdini, the
>>> main thing the people from Fusion CI is doing is just slving the lack of
>>> deontrol in the RF mesher, basically doing stuff you can do in SOPs.
>>> Fluid solvers can get nice results at mid scales but not a so small
>>> scales,
>>> that?s truth, but you can get the overall motion sing SPH or grid
>>> solvers,
>>> the trick is the look. Their main achieve is to get a smooth thin layer
>>> of
>>> geometry from the particles created in RF. This is perfectly doable in
>>> SOP
>>> using particles created from DOPS or even RF. I remember doing simialr
>>> stuff
>>> some years ago in the H8 times using RF particles in Houdini to get a
>>> decent
>>> mesh.
>>> Then you have a plethora of tools like Particle surfacer, Smooth, Preak,
>>> magnet, Convert, etc ... to get a nice mesh in Houdini.
>>> Finally to get the finest and high frequency details you have
>>> displacement
>>> shaders on your arsenal.
>>> Voila Smorganic!
>>> I have seen lots of amazing sims from these guys but the stuff around
>>> smorganinc is just marketing around some techniques to fix and massage
>>> meshes created from particles simulated using SPH. Stuf that Houdini TDs
>>> have been done for years.
>>> We have been living with Smorganics and we didn?t know, Oh my godness!
>>> My 2 cents.
>>>
>>> 2010/4/17 Ozgur Y?lmaz <eoyilmaz at gmail.com>
>>>
>>> > first of all, David Johnson; you were write about being not specific,
>>> sorry
>>> > about that, as you correctly guessed the thing I want to achieve was to
>>> > have
>>> > a continuous thin sheet of water.
>>> >
>>> > Alex and Szymon, thank you for your links, those were very helpful...
>>> >
>>> > After reading the article about smorganic, I remembered that the fluid
>>> > motion is estimated as vorticities and divergences about a point, so
>>> the
>>> > motion of moving away or moving towards a point called the divergence,
>>> and
>>> > moving or spinning around a point is called vorticity. I had a book
>>> > (probably left at the studio) where it was explaining the whole idea
>>> behind
>>> > the fluid dynamics, I need to look at that book again (need to wait
>>> till
>>> > Monday :) ).
>>> >
>>> > As Szymon suggested, I need to add my own nodes to the particle fluid
>>> > solver, nodes that searches for low divergent areas and creates new
>>> > particles.
>>> >
>>> > So thank you guys again, you enlightened me.
>>> >
>>> > Cheers...
>>> >
>>> > E.Ozgur Yilmaz
>>> > Lead Technical Director
>>> > www.ozgurfx.com
>>> >
>>> >
>>> > On Sat, Apr 17, 2010 at 9:09 PM, Szymon Kapeniak
>>> > <szymon.kapeniak at gmail.com>wrote:
>>> >
>>> > > Go it. Thanks!:
>>> > >
>>> > >
>>> >
>>> http://www.cgw.com/Publications/CGW/2009/Volume-32-Issue-12-Dec-2009-/Vie...
>>> > >
>>> > > 2010/4/17 Alex Czetwertynski <alex at franktheplumber.com>:
>>> > > > If you can find it, get the CGW (Computer Graphics World) issue
>>> from
>>> > > > december 09 (the one with Avatar on the cover). The Fusion CS
>>> people
>>> > > > wrote an article on smorganics and how it works within realflow
>>> > > >
>>> > > >
>>> > > > On Apr 17, 2010, at 7:12 AM, Fran?ois Duchesneau wrote:
>>> > > >
>>> > > >> And with a Vop Pop you can have lots of control on the behavior of
>>> the
>>> > > >> global force and letting the sph make the particles stick
>>> together.
>>> > > >>
>>> > > >> Fran?ois
>>> > > >>
>>> > > >> Szymon Kapeniak wrote:
>>> > > >>>>> I've looked at the orbit node but it seems like it orbits a
>>> bunch
>>> > > >>>>> of
>>> > > >>>>> particles around another particle, my problem is to fill new
>>> > > >>>>> particles
>>> > > >>>>> (probably to a position where the density is below a threshold)
>>> > > >>>>> into a
>>> > > >>>>> fluid
>>> > > >>>>> simulation...
>>> > > >>>>>
>>> > > >>>>> I'm quite new in DOPs/POPs in houdini (although I'm much more
>>> > > >>>>> experienced
>>> > > >>>>> with SOPs), so I don't know how to setup a system that adds new
>>> > > >>>>> particles
>>> > > >>>>> to
>>> > > >>>>> an ongoing simulation...
>>> > > >>>>>
>>> > > >>>>> Thank you...
>>> > > >>>>>
>>> > > >>>
>>> > > >>> How close you can come to Fusion demos this is another story of
>>> > > >>> course, but my suggestion would be to dive into sph solver in
>>> DOPs
>>> > > >>> and
>>> > > >>> look around. Basically it consists with a series of microsolvers
>>> > > >>> computing different qualities of fluids. You can turn on / turn
>>> off
>>> > > >>> any of them (open asset and start play with it) - I think only
>>> > > >>> density
>>> > > >>> is mandatory for other solvers to work properly. You can for
>>> example
>>> > > >>> turn off all external forces and pipe a pop solver instead to a
>>> > > >>> chain.
>>> > > >>> If you point it to a pop network (like the one created for you by
>>> a
>>> > > >>> shelf tool "Particle Fluid from Object", you can control fluids
>>> like
>>> > > >>> they were particles, but they look rather like computed by sph. I
>>> > > >>> suspect this is what is happening in Fusion demos inside RF.
>>> > > >>>
>>> > > >>>
>>> > > >>>> 2010/4/17 Alex Czetwertynski <alex at franktheplumber.com>:
>>> > > >>>> I was at a presentation at DMALA where the Fusion guy was
>>> showing
>>> > > >>>> this. He made a big point about it being a Realflow solution
>>> only.
>>> > > >>>>
>>> > > >>>
>>> > > >>> Perhaps in terms of amount of particles which practically can be
>>> > > >>> computed, this can be done by RF only.
>>> > > >>>
>>> > > >>>
>>> > > >>>> I think you should have been more specific in what about the
>>> > > >>>> example you
>>> > > >>>> were looking to recreate. Fran?ois' suggestion of the orbit pop
>>> > > >>>> would be for
>>> > > >>>> making the particles move in the vortex, but my guess is that
>>> > > >>>> you're trying
>>> > > >>>> to make the water stay in a nice thin sheet as it moves. That is
>>> a
>>> > > >>>> much
>>> > > >>>> harder task. Maybe you could contact the guy from Fusion CIS to
>>> > > >>>> see if you
>>> > > >>>> could license his solver and use it in DOPs. Just a thought.
>>> > > >>>>
>>> > > >>>>
>>> > > >>>
>>> > > >>> Aren't they using vanilla Realflow with custom scripting?
>>> > > >>> _______________________________________________
>>> > > >>> Sidefx-houdini-list mailing list
>>> > > >>> Sidefx-houdini-list at sidefx.com
>>> > > >>>
>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> > > >>>
>>> > > >>>
>>> > > >> _______________________________________________
>>> > > >> Sidefx-houdini-list mailing list
>>> > > >> Sidefx-houdini-list at sidefx.com
>>> > > >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> > > >
>>> > > > _______________________________________________
>>> > > > Sidefx-houdini-list mailing list
>>> > > > Sidefx-houdini-list at sidefx.com
>>> > > > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> > > >
>>> > > _______________________________________________
>>> > > Sidefx-houdini-list mailing list
>>> > > Sidefx-houdini-list at sidefx.com
>>> > > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> > >
>>> > _______________________________________________
>>> > Sidefx-houdini-list mailing list
>>> > Sidefx-houdini-list at sidefx.com
>>> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>> >
>>>
>>>
>>>
>>> --
>>> Un saludo
>>> Best Regards
>>> Pablo Gim?nez
>>> _______________________________________________
>>> Sidefx-houdini-list mailing list
>>> Sidefx-houdini-list at sidefx.com
>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
>>>
>>
>>
>
Hello
This is my first post, been lurking around for a while...
Been using Houdini for only a few months, so excuse the newbie tone of
this question...
I'm interested in using Houdini to create shapes of this sort
http://xahlee.org/SpecialPlaneCurves_dir/specialPlaneCurves.html
What would be the way to go about creating, say, a Lituus shape? It
seems to me that the type of equation that is being used contains
symbols that I have never seen in Houdini, but I could be wrong.
Thanks!
Alex
Hello
If I start a render at night and come back to it in the morning, using
Mantra, is there a way to know how long the render took? For one
frame or for an entire animation? I looked at the info button, but it
only tells me when the render started, not when it ended...
Thanks
Alex
I am coming up against the same problem again. There is no kwargs in
menu scripts. so if your writing a menu script in python that is on a
multi-parm the script wont know what parameter it is on. If anyone
knows of a workaround for having a menu script know what its parameter
is i would be thank full. Last time i asked this question i was on the
Alpha of H10 and python menu scripts weren't out yet.... so hopefully
some one has workaround this oversight.
Robert.
Hi Peeps
I am integrating a VopSop with a ramp and promoting it once to an
asset at object level then inside another Subnet asset that gets
interacted with, it has 12 of the object assets. so....
+ main subnet asset (locked)
+ obj asset 1 (same type of asset for the siblings)
+ vop_sop_with_ramp
+ obj asset 2 (same type of asset for the siblings)
+ vop_sop_with_ramp
+ obj asset 3 (same type of asset for the siblings)
+ vop_sop_with_ramp
+ obj asset 4 (same type of asset for the siblings)
+ vop_sop_with_ramp
+ obj asset ...... up to 12
so can i promote a ramp parm from the vop sop to the object level then
have all of the obj assets read one ramp?
It always seams to turn the reference of a ramp into a bunch of ch()
references that are specifically keyed into the one time you promote
the value. Many child ramps referring to one parent ramp isn't a
smooth operation.
I could use a point sop and a chramp() expression but this makes a 130
ms operation into a 2300 ms operation and that times 12 is a big hit.
My plan B is to sample the ramp into 100 points of geometry and use
that geometry as a representation on the ramp.
if you have any ideas on a better way or something i am missing let me know.
Hi Peeps
I am making a shot of debris from an explosion. I tried to load the
chunks as delayed loaded, point instances and they rendered fine
except without motion blur. i tinkered about with many settings and i
eventually reduced the res of the chunks and copy stamped them on.
On my way to trying to get it to work i made quickly moving cubes in
the scene that had correct blur along with the point instance rendered
chunks that had long streaks that ware > 5 times longer than the
distance traveled in the previous frame. I am guessing i have to do
something with the motion file in the mantra delayed load shader.
The shot is working now with the more standard copy stamped geometry
but i still want to know what I need to do to get the delayed load,
point instanced, particle method to work in future.
RObert.
I'm curious if anyone knows a good node or way to reduce and increase polys on geometry.
The object I am working with is nice clean quads. I DO NOT want to triangulate the shape. I have more than enough polys in the Y direction and not enough in X. I was surprised when I went to use the subdivide sop that it would only work on all the polys evenly and I couldn't choose to control the direction. I think I am forgetting about another sop that does this?
Also, for reducing geo, the polyreduce sop is not ideal since it's again working via triangulating and the facet sop (consolidate points etc.) seems to also be choosing to consolidate via triangulation.
I am hoping to get some low rez proxy geos later this week from the modelers but any quick tips would be appreciated.
Thanks,
Erika
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anyone remember an ad by a52 with robot that destroys everything and the
car at the finish?
car explosion looks so great, I'm curious how it was made, just
particles+metaballs, or maybe it wasn't made in Houdini
B
