Sheet Ghost Dynamic Simulation

EldritchCellar

Hello. I have an image in mind that uses a variation on the sheet ghost theme. I considered painting this in photoshop but I'd prefer to utilize a 3d rendered object for the ghost aspect as a start. I suppose I could model the ghost from scratch but I think it would be more convincing (and less laborious) if I utilized a dynamic cloth process as the base object. In the past I would have modeled a primitive under form and draped a uv'd high poly plane over it in Poser via its dynamic cloth simulator. I no longer use or have poser installed. Is a simulation such as this possible in carrara? I'm using 8.1 pro and no plug ins. I'm looking to do the simulation in carrara with the available tools without installing or fussing with add ons, if possible. Thanks

Diomede

Carrara has native soft-body physics which is fine for a still objects, but has very high calculation times for animated keyframed objects.  So, if you are doing a still, this would work fine.  If you are doing an animation of the ghost moving, the calculation times would be impractical and you have to create "undersuits," which I won't bother explaining because you won't do it.

 

But here is an intro to Carrara physics, which should work fine to recreate the image that you posted.

http://carraracafe.com/tag/bullet-physics/

Diomede

Quick example with a square vertex sheet and an oblong vertex sphere.

- make sure have applied a modifier to the sheet - in this case a softbody physics modifier.  Play with settings to reduce stiffness etc. - see attached

- In scene tab, under physics, make sure bullet is selected and softbody says yes. - see attached

- In object effects tab, adjust the bounce and density of the sheet. - see atached

- Start simulation by clicking the magic wand looking thing in upper left of Assemble room.

- Be patient while the physics animation calculates.

- Adjust settings and repeat

 

Not a bad ghost for 10 minutes of playing around.

 

EldritchCellar

Perfect Diomede! Thank you so much for the tips, you're consistently helpful.

Stezza

I did these two a while go using soft body physics on a grid plane

Persona Non Grata

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EldritchCellar

...fiddling about quite a bit with this and having trouble with the sheet penetrating the collision under form (an elongated sphere). I've experimented with various collision under forms, from highly modeled to basic primitives. I'll keep fussing with it... I'm interested in knowing the settings that stezza used to achieved the form on the ghost figure on the right side of the attached image... Sigh. There really isn't any documentation (that I'm aware of) for settings such as collision distance, friction, density, etc. Which I suppose is a horse that's been beaten to death.

EldritchCellar

Another problem, upon tweaking settings, is the sheet sliding off the under form entirely. I'll keep plugging away at it...

EldritchCellar

I'm getting the impression that the poke through and slide off has something to do with the collision distance in combination with some other setting.

Persona Non Grata

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EldritchCellar

Hi selina. Yes. The problem is that the sheet is passing through the under form entirely and falling into space. I'm not using a floor. I have had some success draping the sheet without sliding off or poke through but the sheet in these instances isn't hanging with enough gravity. I suppose I could fix that with a bit of sculpting in zbrush but I'm concerned, in doing so, about some dramatic need for readjustment of the uv map of the sheet. My major reason for attempting to use physics on a 3d object is an attempt to avoid the headache of convincingly modeling drapery and folds. A calculation such as this was a pretty straight forward process back in the day using Poser's Cloth simulator. But now I'm using Carrara. I can't help but find some measure of grim humor with myself having such a hard time creating a simple form as a sheet ghost primitive considering that a couple years ago I created the attached image (winner of 1st prize in the renderosity Halloween contest) using wings3d, zbrush, poser, and photoshop. I'll keep experimenting and hopefully come up with something reasonable. Barring that it may be necessary to utilize a more expressionistic, painterly approach to this. In this case it may be counterproductive creatively to spend so much time getting bogged down with finicky technical vagaries of software. Realism isn't the strict aim. This may require a more lateral approach as my free time is limited and this idea needs to be gotten underway. In any case it's an interesting learning process involving Carrara, which is always welcome, as I really like the software. It's cozy for me lol. Thanks, and love the material settings on your ghost images btw.

Persona Non Grata

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Hermit Crab

I was uncertain whether I could offer any advice here but I'll offer the following anyway:  It should be possible to create one object consisting of the plane to be draped and also the shape underneath which it will drape over.  The 'plane' could be a circular disc, rather than a square.

Apply a 'soft body' modifier to this two-part object.

Now apply a 'soft body attach' modifier to it and paint the vertices of the sphere, or whatever shape is going to be underneath.  You will probably need the brush to be tiny to reach underneath if the two parts are close together.  Set the object to self-collide.

Alternatively you could try it with two objects.  This time, the plane or circle probably needs a few central vertices painted as soft body attach and the shape underneath is an ordinary object   'Soft body attached'  vertices, if not attached to anything just attach to world space and these vertices are exempt from the simulation.  But you could attach the aformentioned few vertices of the plane/circle object to a cone or something similar.  The cone could be slowly lowered along the timeline so that the cloth, during the simulation gets lowered with it.

The cloth will swish back and forward, probably, depending on stiffness, number of vertices it has, etc. but will settle in time.

Regarding the videos Selina mentioned, I was surprised when I looked that I am the guilty culprit who made them when I was an almost complete beginner in Carrara.  I went on and on with the topic in a long thread as a newcomer to forum posting and am quite embarrassed looking back at that and at the poor quality of the videos (and most others since).

I've been meaning for a long time to delete all my YouTube videos and start again as a slightly more experienced hobbyist but I don't know now if the physics vids should be kept.  They should come with a 'seriously tedious and boring to watch' warning, I think!  

Edited for spelling

EldritchCellar

Hi Marcus Severus. I think I may have come up with a usable simulation. I ended up modeling a ghost shaped cone with rounded top and draped this over a sphere. The model was medium resolution in poly count and I used a smoothing setting of 2 during the simulation. It resulted in a VERY long simulation but the shape turned out similar to what I was looking for. I untriagulated and decimated it some. Carrara unfortunately LOVES to triangulate models. My uv map is wrecked. I'm going to bring this result into zbrush and fuss with it a bit. Hopefully I come up with something usable. If not I'll try again armed with the knowledge of the mistakes I've made so far. Thanks for your input, added to my menu of attempts.

EldritchCellar

Update... 82000 polys, all quads. Decimation didn't work properly but miraculously my uvs survived, without distortions, upon testing. I had hoped to top out at less than 60 k. Maybe in the next attempt. Off to zbrush for some tweaking and smoothing.

Hermit Crab

I'm glad to hear that you're getting there.  I think every attempt at doing something in soft-body physics needs this kind of repeated trying out of settings.  Predicting what will happen isn't really possible but I used to start with Bending at zero and Stiffness of around 22-26 percent.  If the cloth didn't stretch well, I would sub-divide.  (Sub-dividing necessitates re-doing the painting of vertices in soft-body attach). 

Edited to re-word last sentence

 

EldritchCellar

I've discovered that the simulation caused splits in the mesh, strangely at the uv seams. I'm not sure if this occured during the sim or during untriagulation. Pretty sure it happened during the sim. I'll have to reweld those verts where it would be potentially visible during render. Fortunately most of the main seam is at the back of the model. Looking over this model I'm not convinced that using a simulation was the way to go for this. But I did learn quite a bit about physics in Carrara. I may post my finished image here once complete if I'm happy with it. Thanks again all.

Stezza

EldritchCellar said:

I'm interested in knowing the settings that stezza used to achieved the form on the ghost figure on the right side of the attached image... 

yeah.. I can't remember the setting I used but would of been similar/close to what's in the attached image which I just did.. only took a few seconds to animate..

what I did do after the similation which only takes a few seconds, is slide the frame bar thingy ( I'm not an animator ) to a frame I like then I export the result to an OBJ file then re-import it to use.

Very similar to what Selina mentions..

setting on this quickie are:

Stiffness - 15%
Bending 0%
Smoothing - 1

I would of also set the Quality to 15% but not for this one as it was quick and rough ..

hope this helps you 

Persona Non Grata

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Stezza

Thanks @Selina 

didn't realise that... always learning something new here 

de3an

Selina said:

Stezza, no need to export to .obj and then import back into your scene - you can simply use the EDIT -> Convert Deformed Object to Mesh option instead. It creates a new object right there in your scene at the correct size and location.

 

Selina,

Where is this "EDIT -> Convert Deformed Object to Mesh" option? I don't have it under my Edit menu (see attached image). I'm using Carrara Pro 8.5.1.19. Do you have a plug-in that gives you this function?

EldritchCellar

de3an said:

Selina said:

Stezza, no need to export to .obj and then import back into your scene - you can simply use the EDIT -> Convert Deformed Object to Mesh option instead. It creates a new object right there in your scene at the correct size and location.

 

Selina,

Where is this "EDIT -> Convert Deformed Object to Mesh" option? I don't have it under my Edit menu (see attached image). I'm using Carrara Pro 8.5.1.19. Do you have a plug-in that gives you this function?

Maybe Selina is referring to Edit:Convert To Other Modeler. Choose vertex modeler to convert to a facet mesh.

EldritchCellar

Please note: there's a 99% chance that I'm wrong though lol.

de3an

EldritchCellar said:

de3an said:

Selina said:

Stezza, no need to export to .obj and then import back into your scene - you can simply use the EDIT -> Convert Deformed Object to Mesh option instead. It creates a new object right there in your scene at the correct size and location.

 

Selina,

Where is this "EDIT -> Convert Deformed Object to Mesh" option? I don't have it under my Edit menu (see attached image). I'm using Carrara Pro 8.5.1.19. Do you have a plug-in that gives you this function?

 

Maybe Selina is referring to Edit:Convert To Other Modeler. Choose vertex modeler to convert to a facet mesh.

 

That doesn't seem to be the case. To make soft body draping work it appears that you must start with a tessellated vertex object. You can't convert to the vertex modeler if the object is already a vertex object.

EldritchCellar

I'm curious as to what and why it would need to be converted for/to at all in that case. I've noticed that quad .obj meshes are triangulated after the application of modifiers though. My simulations have been done on imported quad .obj models. Is a vertex object Carrara's terminology for a subdividable .obj? Still trying to work through the specific obscure quirks of Carrara.

EldritchCellar

I guess my point is... If an object that has been deformed is already a vertex object, which is a mesh (with vertices or vertexes if you prefer, edges, and faces) why would it need to be converted to a... Mesh? Lol

EldritchCellar

Maybe to bake the simulation deformation? Answering my own questions now.

Persona Non Grata

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Persona Non Grata

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de3an

Selina said:

de3an said:

Selina,

Where is this "EDIT -> Convert Deformed Object to Mesh" option? I don't have it under my Edit menu (see attached image). I'm using Carrara Pro 8.5.1.19. Do you have a plug-in that gives you this function?

Yes it's DCG Anything Groves plugin - now free!

Selina

 

Excellent, thanks! That explains it.

I have all of the DCG plug-ins, I just haven't installed them all yet. I just added Anything Grooves and indeed I now have that function (along with all of its other capabilities, which I haven't checked out yet).

Persona Non Grata

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