3D:Simulation Properties

Simulation Properties dialog holds physical attributes of the 3D World, Solver options and other attributes of the various forces involved in a cloth simulation.

Icon & Location

• 
  (Ctrl+Shift+`)
  
• Toolbar: 3D
• Menu: 3D

Operation

1. Click on the Simulation Properties icon on the 3D Toolbar or select it from the 3D Menu. This will launch the Simulation Properties dialog.
2. You may launch and adjust the Simulation Properties even as the simulation takes place.
3. Select OK to approve changes and close the dialog or Cancel to close the dialog without saving changes.

Dialog Description

Time

Time Step (sec)

• The constant time interval between the successive positions of the cloth, from the start of the simulation up to the point in which the garment is in rest position.
• Default Time Step is 0.02 of a second.
• Bigger Time Step (up to 0.4) will result in a more efficient (less time consuming) and less accurate simulation results.
• Smaller Time Step (up to 0.01) will result in a more accurate result and with a longer computational time.

Iterations P. Frame

• Number of times the solver is engaged until automatic full stop.
• By default the solver is running 10 times until full stop.
• Fewer Iterations will be less time consuming but also less fitting for complex designs. Decrease the number of Iterations to speed up simulations of relatively simple designs.
• More Iterations will be less efficient but more fitting for complicated designs which require more calculations.

Springs

Stitch Const

The Stitch Const parameter determines the strength of the spring in the stitch.

• The default value of the Stitch Const is 250.
• A higher value will cause the stitch to contract faster.
• A lower value will cause the stitch to contract slower.

Stitch Damping

The Stitch Damping parameter determines the stability of the stitch.

• The default value of the Stitch Damping is 0.15.
• A higher value will result in a stronger and more stable stitch which is less sensitive to changes.
• A lower value will result in a more dynamic stitch which respond to slighter changes.

Solver Settings

Hybrid IMEX

Hybrid IMEX solver begins the simulation with the Explicit solver and after a few iterations switches to the Implicit solver. This is the default type of cloth simulation in OptiTex 3D, designed to shorten the simulation time and yet to run a highly accurate simulation.

Implicit Only

Check this option to run the Implicit solver which is more accurate than the Explicit solver and also consume more computational time.

• Note - To simulate Inflated Objects, seamless garments and stretchy fabrics always use the Implicit Only.

Explicit Only

Check this option to run a faster but less accurate simulation.

Constraint Iterations

After each iteration of the Explicit solver, there's a deformation repeat on over-stretched springs to shrink them back to natural length.

World

Gravity

• The Gravity parameter imitates the force of gravity to pull cloth objects in a fixed direction - downward or upward - during the simulation.
• The default value of the Gravity parameter is that of planet Earth which is -9.81, meaning 9.81 meters per second squared downward.
• To pull objects upward use values higher than 0.
• For Inflated objects and Bags use zero Gravity.

Collision Tol

In order to simulate cloth pieces over a 3D model there has to be collision between the cloth and the model, otherwise the cloth will pass through the model. See Collision Dialog.

• 3D Models and objects provided by OptiTex collide with cloth objects by default.
• The Collision Tol (Tolerance) sets the distance between the cloth and the model's surface. In other words, the cloth will not collide with the body itself but with an invisible bulge surrounding the model.
• The default Collision Tol is 0.2 cm and it can go up to 1 cm.
• To simulate heavy and rigid garments such as jackets and coats use high values of Collision Tol (0.5 - 1).

World Damping

The World Damping parameter determines the resistance of the simulated cloth to the air.

• The default value for the World Damping is 5.
• A higher value would lead to slower gathering of the cloth. Use it in cases where the simulated garment has many folds that needs to be smoothly laid one another.
• A lower value would lead to faster gathering of the cloth.

Use Pressure

Check this box to set an artificial air pressure. The Pressure parameter is used mainly to simulate inflated objects and quilted garments.

• As a default the Use Pressure option is disabled.
• To simulate Inflated products use pressure value in the range of 1-500 according to the size of the object and to the fabric's parameters.
• To simulate quilted garments use pressure value of 1-10.
• The air pressure is always applied against the inside of the mesh, to inflate the inner side of the simulated object.

Ignore Symmetry

Check this option to place one copy of a piece regardless of the quantity that was assigned to it in the Piece Properties. Also, If a piece was set to half then only the active side of the piece will appear.

• As a default the Ignore Symmetry option is disabled.

3.Disabled

4.Enabled - only half piece appears

Use Self Intersection

Check this option to untie places where the cloth crosses through itself.

Soft Bending

Check this option to simulate soft fabrics unlike rigid fabrics used for hats, bags etc.

Restore Defaults

Click this button to set all the default values and options to the Simulation Properties dialog.