Preferences

The Preferences dialog provides access to application-wide settings that affect all projects. Use it to customize Volvicon's behavior, appearance, performance characteristics, and default import options.

note

Changes to most settings take effect immediately. DPI-related settings require an application restart to apply.

A more complete example is available in the preferences_operations.py tutorial script that ships with the scripting tutorials.

Opening Preferences

1. Open the File tab
2. Click Preferences in the navigation panel

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Settings Tabs

The Preferences dialog is organized into the following tabs:

Tab	Purpose
User Interface	Window behavior, DPI scaling, font size
General	Working directory, undo/redo, performance, data collection
Rendering	Render view interaction options
3D View	Clipping visualization, mask preview settings
2D View	Slice view caching options
Import	CAD file and multi-part import options

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User Interface Settings

Control the visual appearance and behavior of the application window.

Window Options

The UI options group holds:

Setting	Description
Save application size and position on exit	Restore the window size, position, and maximized state on the next launch
Set border in fullscreen	Draw a border around the window in fullscreen mode
Show splash screen	Display the splash banner while the application starts

DPI and Scaling

The same group holds the high-DPI settings:

Setting	Description
Enable high DPI scaling	Allow the interface to scale on high-resolution displays
High DPI scale factor	How the scaling factor is rounded

High DPI scale factor options:

Option	Behavior
Auto	Automatic selection
Round	Round to nearest integer
Ceil	Round up to next integer
Floor	Round down to previous integer
RoundPreferFloor	Round, preferring floor on tie
PassThrough	Use the exact factor without rounding

warning

DPI-related changes require restarting Volvicon to take effect. Save your project before changing these settings.

Application Font Size

Option	Description
System default	Match system font settings
Normal	Standard application font size
Medium	Slightly larger text
Large	Larger text for improved readability
Extra large	Maximum text size

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General Settings

Configure core application behavior, performance, and data collection preferences.

Default Working Directory

The working directory is used for:

• Default location for file dialogs
• Storage location for undo data when saving to disk
• Temporary file storage

Click Browse to select a custom directory, or leave empty to use the system default.

Undo/Redo Configuration

Setting	Range	Default	Description
Maximum number of undos	0 to 999	10	Scene actions kept in the undo history
Maximum number of camera undos	0 to 999	20	Camera positions kept, undone with Ctrl+B and Ctrl+G
Clear			One button beside each limit, discarding the history it belongs to
Save undos to	RAM or Disk	RAM	Where the undo history is held
Maximum memory for a single undo state	0 to 4194304 MB	Derived from installed memory	An undo state larger than this is written to disk instead of being kept in memory
Maximum memory for all undo states	0 to 4194304 MB	Derived from installed memory	Memory target used to discard older data-heavy undo states when possible

Storage Options:

Option	Benefits	Trade-offs
RAM	Faster undo/redo operations	Higher memory usage
Disk	Lower memory footprint	Slower, uses working directory

Memory limits:

The two memory limits work together and are the recommended way to control undo memory on large data.

• Maximum memory for a single undo state decides where one snapshot is kept. Snapshots above the limit are written to the working directory. Smaller snapshots normally stay in memory, but are also written to disk when the current command would exceed the whole-history budget. This applies only while Save undos to is set to RAM, and the control is disabled otherwise.
• Maximum memory for all undo states is a target for the object undo history. When it is exceeded, older history is discarded where possible. The adjacent undo and redo steps are retained, so reported memory can remain above the target. States without object data do not increase the measured memory, although they can be removed with an older history prefix to keep the remaining undo chain contiguous. Maximum number of undos still applies. Camera history has its own limit.

Both default to a value derived from the memory installed on the computer, so a laptop and a workstation each get a sensible value without any configuration. Set the single-state value to No limit (zero) to disable that limit, or set the whole-history value to zero to disable its budget.

tip

For large projects with memory constraints, switch to Disk storage. This writes undo data to the working directory.

caution

Removing the limit on Maximum memory for all undo states lets the undo history grow until only the Maximum number of undos count stops it. On volume data measured in gigabytes this can consume all available memory.

General

Setting	Range	Default	Description
Items to show in recently used files list	1 to 99	9	Length of the recent files and recent projects lists
Maximum number of threads to use	1 to the number your CPU offers	All available	CPU threads used by parallel operations

Performance

Setting	Range	Default	Description
Auto save frequency	0 to 300 min	10 min	Minutes between automatic saves; 0 turns auto-save off
Compression level for project files		Fastest	How hard project files are compressed
GPU acceleration (NVIDIA CUDA)		Automatic	Whether compute-heavy operations may use a supported NVIDIA GPU

Compression Level Options:

Level	Description	Use Case
Store (No compression)	No compression	Fastest save, largest files
Fastest	Minimal compression	The default, and a good balance for most work
Balanced	Moderate compression	Smaller files, moderate speed
Maximum	Highest compression	Smallest files, slowest save

GPU Acceleration

Volvicon can use a supported NVIDIA GPU (via CUDA) to accelerate compute-heavy operations such as CT (cone beam) reconstruction. This is an optional accelerator: the application runs fully on the CPU when no supported GPU is present, so enabling it never restricts Volvicon to NVIDIA hardware.

Option	Behavior
Automatic	Use the GPU when a supported NVIDIA device is available; otherwise use the CPU (default)
CPU only	Always use the CPU
GPU (NVIDIA CUDA)	Prefer the GPU; automatically falls back to the CPU if no usable device is found or the GPU runs out of memory

The selector is only enabled when a supported NVIDIA GPU and a recent NVIDIA driver (release R610 or newer) are detected; otherwise it is greyed out, operations run on the CPU, and the option's tooltip explains why (for example, that the installed driver is too old for the application's CUDA version). When enabled, the tooltip shows the detected GPU. See System Requirements for supported GPUs and driver versions.

note

GPU acceleration applies to compute operations such as CT reconstruction. It does not change 3D rendering, which already uses the GPU through OpenGL on all supported graphics hardware (NVIDIA, AMD, and Intel).

User Experience Improvement

Setting	Description	Default
Help improve user experience	Send anonymous usage and crash data	Enabled

A link to the Privacy Policy is provided for details on collected data.

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Rendering Settings

Configure interaction behavior for all render views.

Zoom Behavior

Setting	Description	Default
Zoom to cursor position	Center zoom operations on the mouse cursor	Enabled

When enabled, zooming focuses on the point under the cursor rather than the view center.

Camera Behavior

Setting	Description	Default
Reset camera when a new object is added	Reframe the 3D view to fit the scene each time an object is loaded or generated	Enabled

When enabled, the 3D camera automatically reframes the scene every time a new object is added, so the newly added object is always in view. When disabled, the camera stays where it is as objects are added, which is useful when you have positioned the view and want it to remain fixed. Resetting the 3D view manually always reframes the scene regardless of this setting.

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3D View Settings

Configure 3D visualization and preview behavior.

3D Clipping Options

Control how the clipping box affects 3D visualization:

Setting	Description	Default
Keep only whole cells when clipping	Keep cells whole rather than cutting through them at the clipping boundary	Enabled
Outline color	Color of the clipping box edges	Black
Handle color	Color of the clipping box manipulation handles	Light gray

Mask 3D Preview

Setting	Description	Default
Automatically regenerate 3D preview if any visible mask is modified	Regenerate existing mesh previews for visible masks after mask edits	Disabled

When automatic regeneration is enabled:

• Visible masks with an existing mesh preview are regenerated after edits.
• Invisible masks with an existing mesh preview are invalidated and must be regenerated when shown again in mesh mode.

Automatic regeneration does not apply to Mask 3D Preview (Direct). In direct mode, mask edits are shown immediately from the mask volume and no mesh preview is rebuilt.

Multilabel Mask

These settings control how the 3D preview surface is built for a mask that contains more than one label.

Setting	Description	Default
Use accurate surface detection for each label in the multilabel mask	Isolate each label and reconstruct a smooth, individually closed surface with subvoxel accuracy	Enabled
Surface extraction algorithm	Choose how each label's surface is built when accurate surface detection is turned off	Smooth closed labels

Together, the accurate mode and the three extraction choices provide four ways to build a multilabel preview:

Mode	Surface and interface behavior	Recommended use	Important limitations
Accurate surface detection	Isolates each label, calculates partial gray values, and reconstructs it independently as a smooth surface designed to be closed. A contact interface is represented separately for each participating label.	Surface-based quality analysis, dimensional inspection, NDT review, per-label measurements, and separate surface export.	Can take substantially longer for masks with many labels. Neighboring labels do not share mesh entities, so the result is not a conforming multi-material mesh.
Smooth closed labels	Builds all labels together, then includes every shared boundary in both adjacent label surfaces. Each label is designed to be closed, while both copies of a shared interface remain geometrically coincident.	Faster closed-label previews, per-label visualization or export, and workflows that need complete label boundaries but do not require the partial-gray reconstruction used by Accurate surface detection.	The combined preview contains duplicate coincident faces at shared interfaces. Smoothing moves boundaries away from unsmoothed voxel transitions; validate watertightness and topology before quantitative or regulated use.
Smooth shared interfaces	Builds smooth boundaries but keeps only one copy of each shared interface, assigning it to one participating label.	Combined multi-label visualization, contact-network review, or preparation for volume meshing and multi-material FEM workflows where duplicate internal faces are undesirable.	A separated label may be open because its shared interface can belong to its neighbor. The combined surface still requires topology validation and may require repair for the target mesher or solver.
Voxelized conforming	Builds unsmoothed, voxel-derived boundaries. Adjacent labels align at shared vertices where possible.	Segmentation review when the unsmoothed voxel boundary is preferred, or downstream processing that accepts discrete and potentially non-manifold surfaces.	Adjacent regions do not necessarily share complete triangle faces; coincident faces and non-manifold topology can occur. It is not a watertight-interface guarantee.

Surface extraction algorithm becomes available only when Use accurate surface detection for each label in the multilabel mask is turned off.

Choosing an analysis-ready surface

Use Accurate surface detection when each label must provide the highest-quality independently closed surface for quantitative or inspection work. Use Smooth closed labels when closed per-label surfaces matter more than partial-gray reconstruction speed. Use Smooth shared interfaces only when the combined interface representation is the intended output and open individual labels are acceptable. Always run the topology checks required by the target analysis or meshing tool; a preview mode alone does not certify a mesh for simulation or regulated measurement.

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2D View Settings

Configure slice view behavior.

Mask Outline Cache

Setting	Description	Default
Enable mask outline cache	Precompute outlines for visible masks	Enabled

When enabled:

• Benefit: Faster slice navigation through volumes with masks
• Trade-off: Higher memory usage for cached outlines

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Import Settings

Configure default import behavior for volumes, masks, and surface models.

Volume and Mask Import Options

Control how Volvicon handles geometry mismatches when importing volumes or masks into projects with existing data.

Geometry Comparison Precision

Define the tolerance used when comparing imported image geometry with the active volume in the project.

Setting	Description	Default	Range
Spacing comparison precision	Decimal places for voxel spacing comparison	3	1–15
Origin comparison precision	Decimal places for origin position comparison	6	1–15

How Precision Works:

The precision setting determines the tolerance for geometry matching. Values are rounded to the specified number of decimal places before comparison.

Spacing Example (precision = 3):

• Reference spacing: 0.56789 mm → rounds to 0.568 mm
• Import spacing: 0.5678 mm → rounds to 0.568 mm
• Result: Match (import allowed)

Spacing Example (precision = 3):

• Reference spacing: 0.56789 mm → rounds to 0.568 mm
• Import spacing: 0.567 mm → rounds to 0.567 mm
• Result: Mismatch (import blocked unless allowed)

Origin precision and NIfTI

The NIfTI format stores voxel spacing and origin as single precision numbers. A volume exported to .nii or .nii.gz therefore comes back with an origin that differs from the original in roughly the fifth decimal place for patient coordinates in the hundreds of millimetres, which the default origin precision of six decimal places reports as a mismatch.

Set Origin comparison precision to 3 when working with NIfTI files, or export to Meta Image or NRRD instead. Both store spacing and origin as text at full precision, so they round-trip exactly. See Export for the format list.

Recommended Precision Settings

Application	Spacing	Origin	Rationale
Medical CT/MRI	3	6	Sub-millimeter spacing, micron-level origin precision
Micro-CT	4–5	2–3	High-resolution imaging with micron-level detail
Industrial CT	3–4	2	Precision measurement requirements

Allow Mismatched Geometry

Setting	Description	Default
Allow import of images with mismatched geometry	Permit importing volumes/masks that do not match the active volume	Disabled

When disabled (default):

• Import operations check dimensions, spacing, and origin against the active volume
• Mismatched images are rejected with a detailed error message showing exact geometry differences
• Ensures all project data shares consistent spatial properties

When enabled:

• Images with geometry differences can be imported
• A warning message appears if resampling is disabled
• Use when combining data from different sources or scanners

Spatial Alignment Considerations

Importing images with mismatched geometry without resampling may result in spatial misalignment. Voxels at the same index position will not correspond to the same physical location. Enable resampling to maintain proper alignment.

Automatic Resampling

Setting	Description	Default
Resample mismatched images to match the project's active volume	Automatically resample imported data to match the active volume geometry	Disabled

When enabled:

• Images detected as mismatched are automatically resampled to match the active volume
• Output dimensions, spacing, and origin will match the reference volume
• Interpolation method is applied according to data type (see below)

When disabled:

• Mismatched images import without modification (if allowed)
• Users must manually resample if spatial alignment is required

Resampling Effects

Resampling modifies voxel values through interpolation. Consider the following effects:

For Volumes:

• Grayscale values may change due to interpolation
• Fine structures smaller than the voxel size may be affected
• Quantitative measurements (density, intensity) may differ from the original

For Masks:

• Label boundaries may shift slightly
• Small structures may be lost if downsampling
• Volume measurements may differ from the original segmentation

Review resampled data carefully before proceeding with analysis.

Interpolation Methods

Select the interpolation algorithm applied during resampling operations.

For Volumes:

Method	Description	Use Case	Default
Nearest	Use value of nearest voxel	Label volumes, discrete data
Linear	Trilinear interpolation	Standard grayscale volumes	✓
Cubic	Tricubic interpolation	High-quality resampling, minimal artifacts

For Masks:

Method	Description	Use Case	Default
Nearest	Use value of nearest voxel	Preserves label IDs, no fractional values	✓
Linear	Trilinear interpolation	Smooth boundaries (may create fractional labels)
Cubic	Tricubic interpolation	High-quality (may create fractional labels)

Interpolation Selection

Use Nearest for masks to preserve integer label IDs and prevent fractional values that would corrupt segmentation data.

Use Linear for volumes as a good balance between quality and speed. Use Cubic only when highest quality is required and processing time is acceptable.

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Surface and CAD File Import Options

Settings for importing CAD formats (STEP, IGES, BREP) and multi-part surface models.

CAD Geometry Handling

Setting	Description	Default
Preserve the original STEP geometry including any non-manifold features	Keep non-manifold features that STEP files may carry	Disabled
Fix solid part(s)	Attempt automatic repair of geometry defects	Enabled

Preserve Original Geometry:

• When enabled, imports STEP files including non-manifold edges and faces
• When disabled, non-manifold features are omitted during import

Fix Solid Parts:

• Attempts to repair gaps, overlaps, and missing faces in solid geometry
• Recommended for CAD data from external sources

Deflection Control

Control the tessellation quality when converting CAD geometry to triangle meshes:

Setting	Description	Default
Auto-calculate deflections	Automatically compute optimal tessellation parameters	Disabled
Linear deflection	Maximum distance between mesh and true surface (mm)	0.001
Angular deflection	Maximum angular deviation between adjacent triangles (degrees)	0.3

Linear Deflection:

• Lower values produce meshes that closely follow curved surfaces
• Higher values produce coarser meshes with fewer triangles
• Typical range: 0.001–1.0 mm

Angular Deflection:

• Controls smoothness of curved regions
• Lower values create more triangles in curved areas
• Typical range: 0.1–1.0 degrees

Deflection Trade-offs

Lower deflection values:

• Benefit: Higher geometric accuracy, smoother appearance
• Trade-off: More triangles, larger file size, slower rendering

Higher deflection values:

• Benefit: Fewer triangles, faster processing
• Trade-off: Faceted appearance, reduced accuracy

Solid Construction

Setting	Description	Default
Build solid	Construct solid geometry from surfaces	Disabled
Intersect parts	Compute Boolean intersections between parts	Disabled
Discard internal part(s)	Remove geometry hidden inside the solid	Disabled

These options apply Boolean operations during import to create closed solid geometry suitable for volumetric operations.

Multi-Part File Behavior

Setting	Description	Default
Import multi-part files as a single surface object	Merge all parts into one object	Disabled

When enabled:

• All parts from STEP, IGES, VRML, or 3DS files merge into a single surface object
• Simplifies object management for assemblies

When disabled:

• Each valid part imports as a separate surface object
• Allows individual manipulation of components

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Scripting

The same application-wide settings can also be automated through the scripting API.

Use the application preferences operations object to read the current preference values and update them from a script:

import ScriptingApi as api

app = api.Application()
preferences_operations = app.get_preferences_operations()

preferences_operations.set_show_splash_screen(False)
preferences_operations.set_zoom_to_cursor_position(True)
preferences_operations.set_spacing_comparison_decimal_places(4)

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Workflow: Optimizing for Large Projects

1. Open File → Preferences
2. Navigate to the General tab
3. Set Save undos to → Disk to reduce memory usage
4. Reduce Maximum memory for all undo states, or lower Maximum memory for a single undo state so that large volumes go to disk while smaller objects stay fast
5. Reduce Maximum undos if memory is constrained
6. Set Compression level → Store or Fastest for faster saves
7. Verify Auto-save frequency is set appropriately
8. Click Close to apply settings

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Workflow: Configuring for High-DPI Displays

1. Open File → Preferences.
2. Select User Interface in the list on the left.
3. Tick Enable high DPI scaling.
4. Set High DPI scale factor to PassThrough for the smoothest scaling.
5. Adjust Font size under Application font if text is too small or too large.
6. Click Close.
7. Restart Volvicon for the DPI changes to take effect.

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Workflow: Configuring Volume/Mask Import Behavior

Configure geometry matching tolerance and automatic resampling:

1. Open File → Preferences
2. Navigate to the Import tab
3. Set Spacing comparison precision based on your data source:
   • Medical imaging: 3 decimal places
   • High-resolution micro-CT: 4–5 decimal places
4. Set Origin comparison precision (typically 6 for medical data)
5. To allow mismatched imports:
   • Enable Allow import of images with mismatched geometry
   • Enable Resample mismatched images to maintain alignment
   • Verify interpolation methods:
     • Volume: Linear (default)
     • Mask: Nearest (default)
6. Click Close to save

When to Adjust Precision

Increase precision (more decimal places) when:

• Working with high-resolution imaging (micro-CT, synchrotron)
• Exact geometric matching is critical
• Datasets should be from identical acquisition protocols

Decrease precision (fewer decimal places) when:

• Combining data from multiple scanners or sessions
• Small numerical variations should be tolerated
• Post-processing has introduced rounding

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Workflow: Optimizing CAD Import

1. Open File → Preferences
2. Navigate to the Import tab
3. Configure CAD file options:
   • Enable Preserve original geometry for complex STEP assemblies
   • Enable Fix solid part(s) to repair problematic geometry
4. Set deflection values:
   • Enable Auto-calculate deflections for automatic settings, or
   • Set manual values for precise control
5. Configure solid options if needed for Boolean operations
6. Set multi-part behavior based on your workflow
7. Click Close to save

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Restore Defaults

To reset all preferences to factory defaults:

1. Open File → Preferences
2. Click Restore Defaults in the dialog button bar
3. A confirmation dialog appears
4. Click Yes to restart the application

warning

Save your project before restoring defaults. The application will restart and unsaved changes will be lost.

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Best Practices

For Performance

• Increase Maximum threads to match your CPU cores for faster processing
• Use RAM storage for undo if you have sufficient memory
• Set Auto-save to a reasonable interval (5–10 minutes)

For Memory Management

• Switch undo storage to Disk for large projects
• Reduce Maximum undos to limit memory consumption
• Disable Mask outline cache if working with many masks

For Display Quality

• Enable high DPI scaling on high-resolution monitors
• Use PassThrough scale factor for best visual quality
• Adjust font size for comfortable reading

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Related Topics

• Save - Project saving and auto-save behavior
• Import - Importing data with preferences
• Properties - Project-specific settings