Configuring Regional Settings

Prev: Part 13: Interpreting Slicer Output

Regional settings let you override print behavior inside specific 3D regions. This is how you tune exposure or motion only where it matters (e.g., membranes, valve seats, or reinforcement zones).

PyMFCAD supports four regional settings types:

  1. ExposureSettings — change exposure parameters in a region
  2. PositionSettings — change motion parameters in a region
  3. MembraneSettings — create thin membranes with custom exposure/defocus
  4. SecondaryDoseSettings — add edge/roof dosing around features

All of them are attached with add_regional_settings(name, shape, settings, label).

How regional settings work

  • The shape defines the affected region (cube, sphere, etc.).
  • The settings define the local overrides.
  • The label is just a color category for visual inspection in the visualizer.

Checkpoint: After adding regional settings, enable the Regional toggle in the visualizer to see the region overlays.

1) ExposureSettings region

Use this to locally change exposure multiplier, power, or focus. This is the most common override.

from pymfcad import ExposureSettings, Cube

region = Cube((40, 40, 10)).translate((30, 30, 20))
device.add_label("region_exposure", Color.from_name("yellow", 127))

device.add_regional_settings(
    name="high_dose_zone",
    shape=region,
    settings=ExposureSettings(bulk_exposure_multiplier=1.5, power_setting=120),
    label="region_exposure",
)

When to use: higher dose near valve seats, thick features, or curing reinforcement zones.

2) PositionSettings region

Use this when a region needs different motion behavior (e.g., longer wait times or slower lift (usually limited by accelerations)) to reduce delamination or suction.

from pymfcad import PositionSettings, Cube

region = Cube((60, 20, 8)).translate((20, 10, 12))
device.add_label("region_motion", Color.from_name("orange", 127))

device.add_regional_settings(
    name="slow_lift_zone",
    shape=region,
    settings=PositionSettings(up_speed=5.0, down_speed=5.0),
    label="region_motion",
)

When to use: delicate membranes, high-aspect-ratio channels, or suction-prone regions.

3) MembraneSettings region

Membrane settings create a thin, locally tuned membrane by controlling max thickness, dilation, and exposure/defocus.

How membrane masking works

PyMFCAD creates membranes by detecting thin regions inside the mask and hole-punching them out of the exposure images, then emitting new images for those layers.

  • The slicer builds a mask for the regional shape.
  • Inside that mask, it scans the geometry and finds any regions with thickness ≤ max_membrane_thickness_um.
  • Those detected thin regions become membranes images and are removed from exposure in the generated image stack for those layers.

Practically, you can:

  1. Explicit membrane shape: Provide a region that tightly bounds the intended membrane; if it is <= max_membrane_thickness_um this becomes a membrane.
  2. Geometry-driven membrane detection: Provide a broader mask and let the slicer find all thin regions (≤ max_membrane_thickness_um) within it.
from pymfcad import MembraneSettings, Cube

membrane_region = Cube((30, 30, 6)).translate((40, 40, 18))
device.add_label("membrane", Color.from_name("purple", 127))

device.add_regional_settings(
    name="valve_membrane",
    shape=membrane_region,
    settings=MembraneSettings(
        max_membrane_thickness_um=20.0,
        bulk_exposure_multiplier=0.4,
        dilation_px=1,
        defocus_um=20.0,
        on_film=False,
    ),
    label="membrane",
)

When to use: microvalves or thin diaphragms that must remain flexible.

4) SecondaryDoseSettings region

Secondary dosing lets you add extra exposure at edges or roofs above features. This helps stiffen or seal critical regions.

from pymfcad import SecondaryDoseSettings, Cube

sec_region = Cube((50, 50, 10)).translate((25, 25, 20))
device.add_label("secondary_dose", Color.from_name("red", 127))

device.add_regional_settings(
    name="edge_roof_reinforcement",
    shape=sec_region,
    settings=SecondaryDoseSettings(
        edge_bulk_exposure_multiplier=0.27,
        edge_erosion_px=1,
        edge_dilation_px=1,
        roof_bulk_exposure_multiplier=0.4,
        roof_erosion_px=0,
        roof_layers_above=3,
        roof_on_film=False,
    ),
    label="secondary_dose",
)

When to use: sealing roof layers, stiffening channels, or improving print robustness.

Regional settings vs defaults

  • Defaults (Step 9) apply everywhere within component unless overridden.
  • Regional settings apply only within their shapes.

If multiple controls apply, the priority is: regional > component > defaults.

Common pitfalls

  • Shapes must be within the device volume.
  • Regional settings will not affect subcomponents
  • Use distinct labels so you can inspect regions visually.

Next: Extra 1: Customizing Subcomponent Labels and Colors