Imprint Sketch

Open Tool

Open Imprint Sketch

Imprint Sketch designs procedural directional responses for s3g Ambi Imprint 64 and ambisonic impulse-response banks rendered by 3OAFX Synthetic Ambisonic IR Bank. It replaces IR Sketch and imports projects created by the retired utility.

The tool is an acoustic-response sketcher rather than a measurement or architectural simulator. It supports plausible spaces, exaggerated natural spaces, and intentionally impossible structures while keeping directional arrivals and decay behavior repeatable.

Spaces

The Space menu selects Room, Cave, Cavern, Tunnel, Canyon, Clearing, or Abstract geometry. Each family has its own procedural boundary construction, scale ranges, vertical variation, openness, reflection distribution, and material tendencies.

Room preserves the architectural shapes and connected chambers from IR Sketch. Caves and caverns use irregular closed boundaries, rough surfaces, variable ceilings, and coupled branches. Tunnels and canyons use bent passage topologies with axial returns. Clearings emphasize ground, boundary, and distant scatter responses instead of a dense enclosed tail. Abstract spaces permit deeply folded outlines, contrasting regions, unstable proportions, and extreme combinations of enclosure and openness.

Branch family controls the identity of connected regions independently from their material. Inherit primary keeps every branch in the primary space family. An explicit family can connect unlike spaces, such as an architectural room opening into a cave or a cavern feeding a tunnel. Mixed deterministic chooses a repeatable family for each branch from the project seed and Strangeness value. Family selection changes branch outline, height, path distribution, directional spread, coupling, and energy loss; Branch material remains a separate surface choice.

The Top, Side, and 3D views show the generated boundary and response positions. Bank Map edits directional response positions: drag a response in the plan for X/Y, then use the ELEVATION rail for its Z position. Colored segments on the rail show the primary and connected vertical regions available at that response’s current plan position. Bank Matrix and Reflection Layers compare timing and energy between response groups.

Field X offset, Field Y offset, and Field Z offset position the pickup inside the connected acoustic volumes. Z ranges from the lowest beneath region to the highest overhead region while keeping zero at the primary-space center. The pickup is constrained to a real region rather than empty space between volumes. Drag in Top view to edit X/Y, or drag in Side view to edit X/Z and enter vertically connected chambers.

Connected Volumes

Connected regions can attach to the front, back, left, or right wall, sit overhead, or continue beneath the primary space. Pair placements such as Left + overhead make it possible to compose arrivals from different planes around the pickup. Nested overhead and beneath regions stack vertically rather than being flattened into the floor plan.

Opening shape selects rectangular, arched, circular, elliptical, slot, or irregular portals. Portal width, height, vertical position, area, and shape affect coupling, loss, and directional spread as well as drawing. Branch heading and Cross-position place ceiling and floor regions in plan, while Wall elevation raises wall-attached regions within the available vertical span.

The internal model is a graph of three-dimensional regions joined by portals. Top view distinguishes wall, overhead, and beneath regions; Side and 3D show their actual vertical positions and opening outlines. The graph is saved in project and imprint metadata while its acoustic result is resolved into the ordinary timed AED events consumed by Ambi Imprint.

Open boundary uses the same aperture language as a connected corridor: a dark opening inside a light frame. Its mint frame distinguishes energy escape to the exterior from the pale-blue portals between modeled regions. The opening is shown consistently in Top, Side, 3D, and glTF views.

Generate And Mutate

Generate creates a new space in the selected family. Choose Any family to let the generator select one. Strangeness controls how strongly generation favors irregular boundaries, connected regions, material contrast, vertical variation, field displacement, and unusual reflection timing.

Every generated space has a visible seed. The seed keeps its procedural geometry repeatable and is saved in project and runtime exports. Mutate preserves the current family and overall identity while perturbing geometry, materials, branches, response positions, and timing. Repeated mutations are a quick way to develop related families of spaces.

Directional Responses

First-order boundary events are calculated from the generated polygon rather than from an invisible rectangular room. Floor and ceiling returns respond to surface roughness, vertical variation, and openness. Additional scatter, passage, folded, and connected-region events are generated according to the space family.

Material curves, RT60 values, and natural-space controls are creative estimates. Open spaces intentionally produce sparse returns and reduced late energy rather than behaving like oversized rooms.

Echo Paths

Echo Paths adds deterministic higher-order return structures without turning the imprint into a live feedback processor. Axial return follows the longest primary-room axis, Flutter pair alternates across the shortest opposing surfaces, Coupled chambers derives independent and cross-region portal loops, and Circulating perimeter advances around the primary polygon. Automatic geometry selects among those models from the current topology and space family.

Path interval comes from geometric distance at 343 metres per second. Prominence controls event count and initial level, Persistence controls loss across successive returns, and Regularity moves from perturbed natural timing toward a strict periodic sequence. Dimensions, materials, portal width, region coupling, duration, and the existing reflection count continue to shape the result. Muted violet paths appear in Top and 3D views, while the response timeline and Reflection Layers show their resolved events.

The default is Off, preserving projects created before the echo model. An export stores optional path geometry and provenance, but audio is still resolved into ordinary directional early-reflection entries understood by s3g Ambi Imprint 64.

Export

Export Project writes a versioned s3g-imprint-sketch JSON file that can be re-imported for editing. Legacy s3g-ir-room-sketch JSON remains readable. Version 2 adds space.regions and space.portals; version 1 projects remain readable with wall-attached rectangular portal defaults. The project retains the room-compatible fields required by 3OAFX Synthetic Ambisonic IR Bank while adding the generalized space model.

Export Imprint writes .s3gimprint for realtime use in s3g Ambi Imprint 64. The file contains directional direct arrivals, boundary, scatter, and structured echo events, eight-band absorption and decay data, connected-region information, and procedural-space provenance. Export glTF writes a visual model with the generated boundary, ceiling variation, branches, openings, listener, and response positions. Shaped chamber apertures and frames are preserved, exterior openings retain their dark aperture and mint frame, and wall, overhead, and beneath regions use the same green, blue, and muted-brown identity as the Top, Side, and 3D views.