3D Simulation and Adjustment

Part 1 3D simulation and basic principles

I. 3D simulation

Purpose:
Enable gravity and stitching functions in the 3D scene to simulate garment performance.
Operation Path: 3D Window ➔ Simulation
Operating Instructions:
  • Simulation Type:
Simulate Accurate
Enable simulate for more accurate results (for detail‑oriented processing).
Simulate Normal
Enable simulate to accelerate fabric‑simulation speed (for fast garment creation).
Simulate CPU
Enable CPU simulation for users without GPU hardware (for environments where GPU simulation is unsupported).
  • Simulation Status:
  1. Displays soft properties of fabric; the fabric can be dragged.
  2. Stitches begin to contract and guide lines disappear.
  3. Shows effects caused by gravity, friction and other physical characteristics.
Operation Video:

II. Basic Principles of 3D Simulation

  1. Base first, then refinement: Complete basic simulation first and confirm no major pattern deviation before optimizing details.
  2. 2D before 3D: In case of large‑scale clipping or pattern distortion during simulation, go back to 2D patterns to check stitching, pattern size, dart positions and other settings prior to adjusting 3D parameters.
  3. Fabric matched to pattern: Simulation parameters vary for different fabrics; adjust settings according to fabric characteristics.
  4. Avatar pose matched to garment: Set the avatar pose to fit the garment style, preventing abnormal folds caused by improper posing.

Part II Simulation Properties

Purpose: Adjust the simulation performance of selected patterns in the 3D viewport, so that the display matches expected results.
Operation Path: Select pattern pieces → Property Editor Window → Simulation Properties

I. Particle Distance

  • It defines the simulation precision of pattern pieces in the 3D viewport, referring to the spacing between mesh points.
  • Larger particle distance produces coarser 3D simulation and shorter simulation time.
  • Smaller particle distance delivers finer 3D simulation but requires longer simulation time.
Particle Distance 6
Particle Distance 20
Note: Some fabric‑detail operations can only be displayed under low‑particle‑distance simulation, such as pleats, garment drape details and shirring effects.

II. Layer

Purpose:
Set up overlay and inner‑outer depth details between pattern pieces. During collision calculation, pattern pieces with higher Layer values will shift along the front normal direction of lower‑layer patterns and move outside them.
Operating Instructions:
  • During simulation, pattern pieces with higher Layer values move along the front normal of lower‑layer patterns and shift outside (usually the outer side) of lower‑layer patterns. Generally, outer fabric pieces have higher Layer values than lining pieces.
  • Pattern pieces with assigned Layer values are displayed in green in the 3D scene. After simulation results stabilize, it is recommended to reset the Layer value of both pattern pieces to 0.
Operation Video:

III. Shrinkage Ratio Warp/Weft

Purpose: Control the simulated stretching and shrinking of pattern pieces along warp and weft directions.
Operating Instructions:
  • Higher values produce greater stretching in warp and weft directions during simulation.
  • Lower values result in stronger shrinkage in warp and weft directions during simulation.

IV. Extra Render Thickness

Purpose: Control the visual‑thickness effect of pattern pieces displayed in the 3D viewport.
Operating Instructions: A larger Additional Render Thickness value makes pattern pieces appear thicker; conversely, a smaller value makes them look thinner.
Note: The " Cloth Thickness " option in the 3D floating panel must be enabled for this thickness effect to be visible.
V. Extra Collision Thickness
Purpose: Define the collision volume of pattern pieces after simulation in the 3D viewport.
Operating Instructions: A larger Additional Simulation Thickness value increases the collision volume.

VI. Pressure

Operating Instructions:
  • It controls the expansion effect of pattern pieces under filling materials (such as down and cotton) along the vertical / normal direction.
  • Pressure ranges from ‑100 to 100. Higher values generate stronger inward or outward force applied to pattern pieces.

Part III Simulation Adjustment

I. Common Issues

(1) Minor Clipping

Symptom: Local pattern pieces slightly penetrate the avatar, without large‑scale distortion, and the overall pattern remains acceptable.
Solutions:
Solutions
Operating Instructions
Method 1: Manually adjust the garment position
Select the pattern piece at the clipping area, use the [Move Tool], and slightly drag the pattern piece away from the avatar body until clipping disappears.
Method 2: Tweak simulation parameters
Click the pattern piece and adjust its simulation parameters until clipping is resolved.
Method 3: Fine‑tune 2D pattern pieces
Go back to the 2D Window, check the size of the pattern piece for the clipping area, slightly enlarge the pattern piece, re‑sew it, and run 3D simulation again.

(2) Severe Clipping

Symptom: Multiple pattern pieces penetrate the avatar body; the pattern is heavily distorted and normal preview is unavailable.
Root Causes: Incorrect 2D‑pattern stitching, excessive pattern‑size deviation, and mismatched avatar pose for the garment.
Adjustment steps:
  • Step 1: Stop simulation, switch to the 2D Window, inspect pattern stitching and fix stitching errors.
  • Step 2: Check pattern‑piece dimensions, compare with avatar size, and adjust pattern size to match the avatar measurements.
  • Step 3: Modify the avatar pose (e.g., reduce shoulder width or waist circumference if wide standing pose causes side‑seam clipping), then restart simulation.
  • Step 4: If clipping persists, review fabric parameters (e.g., overly soft fabric or excessive elasticity). Appropriately increase fabric stiffness and run simulation again.

II. Pattern Deviation Adjustment

Types of Pattern Deviation
Symptoms
Solutions
Garment Length / Sleeve Length Deviation
Garment or sleeve length is too long / too short, inconsistent with designed dimensions.
1. Go back to the 2D Window and adjust pattern‑piece length.
2. In the 3D Window, select the body / sleeve pattern and use the [Scale Tool] to fine‑tune the length.
Circumference Deviation
(Waist/Hip)
Circumference is too loose or too tight.
1. Return to the 2D Window and adjust circumference dimensions of pattern pieces.
2. Modify avatar body shape to match garment circumference.
3. Slightly adjust fabric elasticity to improve fitting performance.
Seam‑line Distortion
Garment split seams are uneven and distorted, fitting poorly against the avatar body.
1. Switch to the 2D Window and check stitching of split‑line pattern pieces.
2. IIn the 3D Window, select pattern pieces on both sides of the split seam and manually reposition them to keep split seams smooth.
3. Restart high‑precision simulation.
Dart / Pleat Position Deviation
Dart positions are offset; pleats look unnatural with unreasonable wrinkle distribution.
1. Go to the 2D Window and adjust position and size of darts and pleats.
2. In the 3D Window, use the [Pleat Adjustment Tool] to manually refine pleat shapes.
3. Tune fabric drape parameters for more natural pleats.
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