Dynamics I – 3 Checklists

Hair Room users Checklist

  • Beginners: consult the Case Studies on Hair Room first. This tutorial has no real, detailed Beginners section.
  • Watch your units.
    Poser units can be set in menu Edit > Global Preferences > Interface tab. Internally, Poser works in Poser Native Units (PNU), the translation is done in the user interface. Scripts, which circumvent the user interface, should adhere to PNU.
    Hair length and Variance are expressed in user units. Your 1.0 (inch) is the same as my 0.00254 (meter).
    Hair Density is expressed in square user units. Your 3.0 (hairs per square inch) is the same as the default 32,000 (hairs per square PNU).
  • Watch your counts.
    Hair Density tells the amount of generated hairs by the number in parentheses. Multiplied by the amount of vertices per hair (panel 3, bottom parameter) make the amount of vertices of the hair element at hand. Adding up over all hair elements make the total amount of hair vertices in your scene. Multiplied by say 1kb make the amount of memory required to render.
    For instance: the Toon Puppy has about 37 object parts to be furrified. Using the value from nature; 1,000,000 hairs per square meter generates 1,4 million hairs. At 16 verts / hair make 1,4M * 16 * 1Kb = 20Gb of RAM required for rendering, and might make your system fall over. Bringing down the Hair Density a tenfold, and halving the verts per hair make a requirement of 1Gb for rendering, which can be met by any system.
    So before you start any styling: set the population and other mentioned dials as required for the final result and make a test run, before you’ve got to rework everything from the start in order to get your render out.
  • Watch your Pull.
    These three parameters define an angle between two adjacent edges of a hair. The more verts per hair you set, the more edges a hair is made of, and the more the hair will bend for the same Pull values.
  • Watch your Bend Resistance.
    Because for the result of the simulation, this appears to be the most influential parameter of all.
  • Time your Styling.
    Clicking anything in panel 2, even without changing, nullifies the results from the Hair Editor (the one behind [Style Hairs…] in panel 3). The Hair Editor has no Reset button, but the [Grow Guide Hairs…] one serves a good alternative. And any edit of the Growth Group itself requires the [Grow Guide Hairs] button to be clicked anyway.
    The styling holds after alterations in panels 3 (styling) or 4 (dynamics), but of course the Verts per hair will affect the ease of styling and the result as well.

Cloth Room users Checklist

  • Beginners: consult the Case Studies on Cloth Room first. This tutorial has no real, detailed Beginners section.
  • Watch your steps, and your Garment.
    Just ensure you understand Constraint Groups at least enough to fixate a piece of clothing in space, and then just hang it out for 30 or 60 frames with all default settings. Inspect the simulation.
    Do things fall off? That are candidates for the Soft and Rigid Decorated Groups.
    Check one piece at a time, and check all of them. Anything you knows before, saves time later.
  • Does it bounce and wiggle?
    Or just the opposite? Does it stretch too much? Can you define the kind of cloth you want to mimic in terms of the Dynamic parameters? It’s hard to mimic something you don’t understand enough. The same holds for the physics of nature. Cloth Room mimics physics. Understanding cloth and understanding physics help a lot in managing Cloth Room. In many cases, the simulation is wrecked by the default settings from the start (eq long dresses stretch far too much).
  • Can it be done?As cloth simulations relate to real world physics, things that are hard to do in life are almost impossible to bring to an end easily in Cloth Room. 30 frames of simulation represent 1 second. Some poses or moves cannot be taken or made within 1 second in life. Some moves cannot be made at all, while wearing specific clothes. Tight thick leather pants hamper bending, in life, and in Cloth Room. Long dresses hamper wild dancing or taking hurdles. In Cloth Room too.
  • Do you need All Dynamics?
    As Cloth Room is a nice place to be but conforming clothes have value too. You might need to clothify only a few portions instead of the whole lot. You can put portions of a piece into choreographed or constraint groups, or un-clothify them as a whole.
  • Do you need All Sims?
    When there are more cloth pieces in the scene, some can be combined in one simulation. Others can be combined through multiple simulations, when run (and created) in the right order. Planning ahead might be worth the trouble.
  • Do sims crash or take forever?
    Check and avoid poke-throughs at the start, adjust the collision objects at the start and animate them to the required settings and poses at the end (or sooner).
    Then increase collision depth.
    Then check the collision options (vertex against poly etc)
    Then increase the Steps per Frame
    Check the Quick Clues and Recipes chapter (in part II) for more.

Garment makers Checklist

  • Tailors don’t go naked.
    We do know the tale of the emperors (lack of) clothes, but there never was a tale about tailors going naked. So, make sure you master some basic user skills too, to understand the behavior of your garments.
  • Do the Draping Test.
    Just hang out the garment for 30 or 60 frames and ensure nothing comes off, and all extras are put in the appropriate Soft and Rigid Decoration groups.
  • Be aware
    The Poser manual explicitly states that the Cloth Room prefers single sided, well welded meshes for cloth. You do adhere to that, do you?
  • Understand your Risks and Chances.
    Pockets, buttons, zippers, belt-loops, stitches and pads, all other sorts of accessories place a challenge onto dynamic cloth. Make them Soft or Rigid Decoration items, use Morphs or Displacement maps, model them into or onto the garment but in all cases: know what you’re doing, why, and what the effects are for the use of them.
  • Understand your Mesh Geometry.
    X-tris are to be preferred over ZigZags and Quads (can be compensated for in parameter values), Diagonal tris are worst in simulation behavior.
    Quads make good non-woven cloth (leather, fleece, rubber, …), tris make good woven cloth, hexes make good home knit sweaters.
    Small structures with small polys behave like thinner cloth than structures with large polys, opposite to what most people expect. So varied meshes will show a varied behavior within the same piece of cloth, which will seem unnatural to the user.
    Finer structures reduce crumbling artifacts, especially in quads.
  • Deliver at appropriate detail.
    Clothes wear better when they match the vertex-density / poly size of the figure wearing them. Vicky measures about 20,000 cm2 for 80,000 vertices, that’s an average vertex-distance of 0.5cm (square root of 20,000 / 80,000). Weight mapping is introduced to improve even on that.
    Marvelous Designer states that distances of 20 to 40mm are nice for rough testing (dresses, shirts, figures standing up) but final results require 5 to 10mm.
  • Mind your licensing.
    You will deliver a decent OBJ mesh file, you are the rights owner. Just do one OBJ for each piece of garment, there is no added value in having a quad and a tri version. All Poser specifics, Cloth Room groupings and parameter values included, are in the CR2 file. You may supply multiple of them. Preferably in ways that match material settings, so when a skirt has stripes made of leather, they look like leather and behave as such. And when they are transparent or lace, they behave as such (which is rather different from leather).
    Grant or even encourage people the rights to distribute CR2’s, so they can enrich your product.
  • Document your product.
    Which groupings and parameter settings are delivered with the garments? What have you done to ensure proper dynamic behavior? What do people have to do to handle your products as intended?
    You are not selling to click-and-drag users only, but some of them are. Serve them all.

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