{ "title": "Geometry, acoustics and reconstruction hypotheses — Tools & experiences", "text": "MODAVIS (2026). Geometry, acoustics and reconstruction hypotheses — Tools & experiences. Research notebooks, September 2026 · Connected evidence edition. https://modavis.org/editions/2026-09-r6/software/reconstruction/", "bibtex": "@misc{modavis_software_reconstruction_2026_09_r6,\n author = {{MODAVIS}},\n title = {Geometry, acoustics and reconstruction hypotheses — Tools & experiences},\n year = {2026},\n month = {09},\n version = {2026-09-r6},\n url = {https://modavis.org/editions/2026-09-r6/software/reconstruction/},\n note = {Content SHA-256: f27dc9ad4619ff0d1ca5e262a7234d0ccc8c47ff6d14cbe8171a6a9301bcceed}\n}", "url": "https://modavis.org/editions/2026-09-r6/software/reconstruction/", "sha256": "f27dc9ad4619ff0d1ca5e262a7234d0ccc8c47ff6d14cbe8171a6a9301bcceed", "edition": "2026-09-r6", "date": "2026-09-26", "canonicalPayload": "{\"book\":{\"number\":\"06\",\"slug\":\"software\",\"title\":\"Tools & experiences\"},\"chapter\":{\"blocks\":[{\"id\":\"method-map\",\"text\":\"Choose the representation before the tool\",\"type\":\"heading\"},{\"headers\":[\"Approach\",\"Useful output\",\"Question it can support\"],\"rows\":[[\"Photographic reconstruction\",\"Estimated surface observations, point clouds and camera paths.\",\"What spatial structure is supported by the available views?\"],[\"Parametric component modeling\",\"Geometry generated from explicit dimensions and construction rules.\",\"What follows from this stated geometric hypothesis?\"],[\"Passive pressure-acoustic analysis\",\"Modes or response behavior under specified geometry and boundary assumptions.\",\"How does this modeled acoustic domain respond under those conditions?\"],[\"Room and propagation modeling\",\"A response or field for a stated spatial arrangement.\",\"How might sound reach a receiver within the supported domain?\"],[\"Interactive assembly\",\"A usable combination of visuals, controls, signals and modeled behavior.\",\"How can a person explore or operate this research representation?\"]],\"type\":\"table\"},{\"id\":\"photographic-evidence\",\"text\":\"Modelgenerator: preserve what the cameras support\",\"type\":\"heading\"},{\"text\":\"The current Processor Modelgenerator takes photographic material through a pinned DA3-based workflow to point clouds and camera paths. Its documented output should not be advertised as a finished textured mesh. Camera registration, visible surface coverage and successful transfer of output assets are distinct checks. A coherent cloud can still omit the interior of an object or include poorly supported surfaces.\",\"type\":\"p\"},{\"text\":\"Record the input photographs, processing configuration and coordinate relationship to measurements. Photograph-based geometry and a manually supplied dimension can be combined, but the resulting scale or correction should have a derivation record. A hidden pipe mouth, internal cavity or inaccessible mechanism cannot become an observed surface merely because software produces a complete-looking shape.\",\"type\":\"p\"},{\"boundary\":\"The notebook deliberately provides viewing controls without a physical measurement ruler.\",\"caseLabel\":\"Cuntz\",\"concept\":\"A coordinate frame defines axes, orientation and units. A verified physical scale additionally requires evidence linking those coordinates to the physical object.\",\"evidence\":\"Released record\",\"expanded\":false,\"id\":\"cuntz-coordinates\",\"scenario\":\"The released model declares a right-handed, Y-up frame with metre units, while its purpose limitation says the source scale has not been verified by a physical survey.\",\"sources\":[{\"detail\":\"Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.\",\"href\":\"https://doi.org/10.5281/zenodo.22151203\",\"label\":\"Cuntz Positiv · VAO 0.5.0-rc.2\"},{\"detail\":\"The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.\",\"href\":\"https://doi.org/10.5281/zenodo.22214248\",\"label\":\"VAO Standard 0.5.0\"}],\"steps\":[{\"text\":\"The convention tells a renderer how to interpret model coordinates and orient the scene. It helps two applications agree about the same geometry.\",\"title\":\"Read the coordinate convention\"},{\"text\":\"A declared metre unit does not supply a missing calibration. If the original geometry scale was not verified, a distance computed from its vertices must not be advertised as a measured organ dimension.\",\"title\":\"Read the qualification\"},{\"text\":\"For a documented pipe quantity, inspect the identified measurement observation and workbook source. Use the model to locate and discuss shapes within its stated limitations.\",\"title\":\"Use appropriate evidence for dimensions\"}],\"takeaway\":\"Coordinate consistency allows interchange; metrological validity requires additional evidence.\",\"title\":\"Can we measure the original organ by rotating its model?\",\"type\":\"example\"},{\"id\":\"parametric-acoustics\",\"text\":\"VAO-Pipe: make the geometric hypothesis inspectable\",\"type\":\"heading\"},{\"text\":\"VAO-Pipe belongs to a different route: procedural pipe geometry and passive pressure-acoustic evaluation. Its parameters make a hypothesis explicit and allow controlled variation. That is useful for investigating how selected dimensions and boundary assumptions influence a modeled result. It should remain distinct from a complete account of self-sustained sound production, historical voicing or the actual condition of a surviving pipe.\",\"type\":\"p\"},{\"text\":\"The thesis emphasizes the danger of tuning underdetermined parameters until a desired result becomes inevitable. Preserve the source of each dimension, distinguish measured and inferred values, and identify which observations were used to adjust the model. Compare against independent evidence where available. A close frequency agreement after optimization describes that model and fitting procedure; it does not automatically recover a unique historical geometry.\",\"type\":\"p\"},{\"boundary\":\"No new simulation, measured frequency or complete pipe reconstruction is supplied by this example.\",\"caseLabel\":\"Cuntz\",\"concept\":\"A reconstruction combines evidence with assumptions to produce a possible representation. A simulation computes behavior under specified model conditions.\",\"evidence\":\"Illustrative scenario\",\"expanded\":false,\"id\":\"cuntz-reconstruction\",\"scenario\":\"Suppose a researcher uses the Cuntz GesL observation to help constrain a pipe model. This is an illustrative reconstruction task; the single value is not a complete geometric description.\",\"sources\":[{\"detail\":\"Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.\",\"href\":\"https://doi.org/10.5281/zenodo.22151203\",\"label\":\"Cuntz Positiv · VAO 0.5.0-rc.2\"},{\"detail\":\"Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.\",\"label\":\"Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)\"}],\"steps\":[{\"text\":\"The observation identifies one property, one pipe, one result and one source. It does not provide every interior dimension, material parameter or boundary condition needed by an acoustic model.\",\"title\":\"List what is supplied\"},{\"text\":\"Record the additional dimensions and physical assumptions with their origin. Parameters chosen for convenience should not appear as measured values.\",\"title\":\"Label what is assumed\"},{\"text\":\"If parameters are adjusted to match a known frequency, that same match is not an independent validation. Compare with suitable independent evidence and retain the model’s domain of use.\",\"title\":\"Keep fitting and testing separate\"}],\"takeaway\":\"A plausible reconstruction is a documented hypothesis constrained by evidence, not a recovered certainty.\",\"title\":\"When does a modeled pipe become a historical hypothesis?\",\"type\":\"example\"},{\"boundary\":\"This is a method explanation, not a new Cuntz finite-element result or a claim that the web model is acoustically validated.\",\"caseLabel\":\"Cuntz\",\"concept\":\"Finite-element analysis divides a modeled domain into small connected elements and approximates the governing equations over that mesh. Its result depends on geometry, material or medium properties, and boundary conditions.\",\"evidence\":\"Illustrative scenario\",\"expanded\":false,\"id\":\"cuntz-finite-elements\",\"scenario\":\"Imagine using a documented Cuntz pipe dimension as one input to a passive acoustic model. The 1281 mm observation alone does not describe the entire cavity or its excitation.\",\"sources\":[{\"detail\":\"Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.\",\"href\":\"https://doi.org/10.5281/zenodo.22151203\",\"label\":\"Cuntz Positiv · VAO 0.5.0-rc.2\"},{\"detail\":\"Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.\",\"label\":\"Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)\"},{\"detail\":\"The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.\",\"href\":\"https://doi.org/10.5281/zenodo.22214248\",\"label\":\"VAO Standard 0.5.0\"}],\"steps\":[{\"text\":\"Describe the modeled interior geometry and distinguish measured dimensions from inferred ones. A display mesh of the organ case is not automatically a suitable acoustic domain.\",\"title\":\"Build an explicit domain\"},{\"text\":\"A passive eigenmode calculation asks which patterns and frequencies the specified domain can support under its boundary assumptions. It is not a full simulation of air flow, pipe speech and self-sustained sound production.\",\"title\":\"Specify the physical question\"},{\"text\":\"Check numerical resolution and compare with suitable independent measurements. Refining a mesh can address numerical approximation while leaving uncertain geometry or inappropriate boundary assumptions unresolved.\",\"title\":\"Evaluate the approximation\"}],\"takeaway\":\"A numerical solution answers the equations and conditions supplied to it; interpretation requires checking whether those represent the research question.\",\"title\":\"What does a finite-element pipe model actually calculate?\",\"type\":\"example\"},{\"id\":\"simplification\",\"text\":\"Simplification can remove the feature that matters\",\"type\":\"heading\"},{\"text\":\"A low polygon count is attractive for interactive playback, but visual economy and acoustic relevance do not always align. Section 8.5.1 reports that unweighted simplification below 50,000 polygons damaged features including labia, core gaps and cut-up edges in the investigated setting. A protected weighting of 100 belongs to that configuration; it is not a universal setting for every organ or reconstruction pipeline.\",\"type\":\"p\"},{\"text\":\"Retain a detailed research realization and derive a lighter presentation realization with a documented purpose. Check the features relevant to the question after simplification, not only the final file size. The two realizations can share an asset role while preserving their different bytes, derivations and intended uses. This makes a mobile visualization usable without silently replacing the geometric evidence.\",\"type\":\"p\"},{\"id\":\"pamt\",\"text\":\"PAMT: a proposed architecture for spatial acoustics\",\"type\":\"heading\"},{\"text\":\"PAMT is presented as a conceptual architecture, not a field-validated room-acoustic product. The thesis discusses coupling geometric and wave-based methods because geometric propagation alone cannot represent all low-frequency modal behavior. The transition needs to depend on the room and frequency regime, with reference to the room’s Schroeder frequency, rather than a universal cutoff applied everywhere.\",\"type\":\"p\"},{\"text\":\"No in-situ sound-pressure measurement campaign is reported for PAMT in the dissertation. Its proposed field validation and uncertainty budgets remain prospective. This matters when selecting a tool: the architecture can guide research questions and implementation, but it does not supply measured accuracy for a visitor’s room. A published conceptual method, a working prototype and a calibrated acoustic model are different deliverables.\",\"type\":\"p\"},{\"items\":[{\"detail\":\"Versioned report associated with the pipe modeling and evaluation work.\",\"href\":\"https://doi.org/10.5281/zenodo.22663231\",\"label\":\"VAO-Pipe evaluation\"},{\"detail\":\"See how geometric and acoustic assumptions affect interpretation.\",\"href\":\"/notebooks/research/case-studies/\",\"label\":\"Three case studies\"},{\"detail\":\"Carry the assumptions into the object record.\",\"href\":\"/notebooks/vao/acoustics/\",\"label\":\"Represent responses and spatial frames\"}],\"type\":\"links\"}],\"intro\":\"A point cloud, a parametric pipe, a room-response model and an interactive scene answer different questions. Choose the method by the property you need to investigate.\",\"slug\":\"reconstruction\",\"sources\":[{\"detail\":\"Project documentation inspected on 26 September 2026; package 0.2.0, an unpublished development candidate. Used for current module responsibilities and limitations, not as a claim of public package availability.\",\"label\":\"MODAVIS Processor · module guide and package README\"},{\"detail\":\"Dissertation submitted to Universität Leipzig, 11 September 2026. §5.12.6; §5.15.2; §§8.4.3 and 8.5.1, pp. 277–281. Page numbers refer to the printed manuscript pagination. The manuscript is not distributed by this website.\",\"label\":\"Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)\"},{\"detail\":\"Research report on procedural pipe geometry and passive pressure-acoustic evaluation.\",\"href\":\"https://doi.org/10.5281/zenodo.22663231\",\"label\":\"VAO-Pipe evaluation\"}],\"title\":\"Geometry, acoustics and reconstruction hypotheses\"},\"date\":\"2026-09-26\",\"edition\":\"2026-09-r6\",\"figures\":{}}", "payload": { "edition": "2026-09-r6", "date": "2026-09-26", "book": { "slug": "software", "title": "Tools & experiences", "number": "06" }, "chapter": { "slug": "reconstruction", "title": "Geometry, acoustics and reconstruction hypotheses", "intro": "A point cloud, a parametric pipe, a room-response model and an interactive scene answer different questions. Choose the method by the property you need to investigate.", "blocks": [ { "type": "heading", "id": "method-map", "text": "Choose the representation before the tool" }, { "type": "table", "headers": [ "Approach", "Useful output", "Question it can support" ], "rows": [ [ "Photographic reconstruction", "Estimated surface observations, point clouds and camera paths.", "What spatial structure is supported by the available views?" ], [ "Parametric component modeling", "Geometry generated from explicit dimensions and construction rules.", "What follows from this stated geometric hypothesis?" ], [ "Passive pressure-acoustic analysis", "Modes or response behavior under specified geometry and boundary assumptions.", "How does this modeled acoustic domain respond under those conditions?" ], [ "Room and propagation modeling", "A response or field for a stated spatial arrangement.", "How might sound reach a receiver within the supported domain?" ], [ "Interactive assembly", "A usable combination of visuals, controls, signals and modeled behavior.", "How can a person explore or operate this research representation?" ] ] }, { "type": "heading", "id": "photographic-evidence", "text": "Modelgenerator: preserve what the cameras support" }, { "type": "p", "text": "The current Processor Modelgenerator takes photographic material through a pinned DA3-based workflow to point clouds and camera paths. Its documented output should not be advertised as a finished textured mesh. Camera registration, visible surface coverage and successful transfer of output assets are distinct checks. A coherent cloud can still omit the interior of an object or include poorly supported surfaces." }, { "type": "p", "text": "Record the input photographs, processing configuration and coordinate relationship to measurements. Photograph-based geometry and a manually supplied dimension can be combined, but the resulting scale or correction should have a derivation record. A hidden pipe mouth, internal cavity or inaccessible mechanism cannot become an observed surface merely because software produces a complete-looking shape." }, { "type": "example", "id": "cuntz-coordinates", "title": "Can we measure the original organ by rotating its model?", "concept": "A coordinate frame defines axes, orientation and units. A verified physical scale additionally requires evidence linking those coordinates to the physical object.", "scenario": "The released model declares a right-handed, Y-up frame with metre units, while its purpose limitation says the source scale has not been verified by a physical survey.", "steps": [ { "title": "Read the coordinate convention", "text": "The convention tells a renderer how to interpret model coordinates and orient the scene. It helps two applications agree about the same geometry." }, { "title": "Read the qualification", "text": "A declared metre unit does not supply a missing calibration. If the original geometry scale was not verified, a distance computed from its vertices must not be advertised as a measured organ dimension." }, { "title": "Use appropriate evidence for dimensions", "text": "For a documented pipe quantity, inspect the identified measurement observation and workbook source. Use the model to locate and discuss shapes within its stated limitations." } ], "takeaway": "Coordinate consistency allows interchange; metrological validity requires additional evidence.", "boundary": "The notebook deliberately provides viewing controls without a physical measurement ruler.", "sources": [ { "label": "Cuntz Positiv · VAO 0.5.0-rc.2", "href": "https://doi.org/10.5281/zenodo.22151203", "detail": "Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release." }, { "label": "VAO Standard 0.5.0", "href": "https://doi.org/10.5281/zenodo.22214248", "detail": "The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2." } ], "expanded": false, "caseLabel": "Cuntz", "evidence": "Released record" }, { "type": "heading", "id": "parametric-acoustics", "text": "VAO-Pipe: make the geometric hypothesis inspectable" }, { "type": "p", "text": "VAO-Pipe belongs to a different route: procedural pipe geometry and passive pressure-acoustic evaluation. Its parameters make a hypothesis explicit and allow controlled variation. That is useful for investigating how selected dimensions and boundary assumptions influence a modeled result. It should remain distinct from a complete account of self-sustained sound production, historical voicing or the actual condition of a surviving pipe." }, { "type": "p", "text": "The thesis emphasizes the danger of tuning underdetermined parameters until a desired result becomes inevitable. Preserve the source of each dimension, distinguish measured and inferred values, and identify which observations were used to adjust the model. Compare against independent evidence where available. A close frequency agreement after optimization describes that model and fitting procedure; it does not automatically recover a unique historical geometry." }, { "type": "example", "id": "cuntz-reconstruction", "title": "When does a modeled pipe become a historical hypothesis?", "concept": "A reconstruction combines evidence with assumptions to produce a possible representation. A simulation computes behavior under specified model conditions.", "scenario": "Suppose a researcher uses the Cuntz GesL observation to help constrain a pipe model. This is an illustrative reconstruction task; the single value is not a complete geometric description.", "steps": [ { "title": "List what is supplied", "text": "The observation identifies one property, one pipe, one result and one source. It does not provide every interior dimension, material parameter or boundary condition needed by an acoustic model." }, { "title": "Label what is assumed", "text": "Record the additional dimensions and physical assumptions with their origin. Parameters chosen for convenience should not appear as measured values." }, { "title": "Keep fitting and testing separate", "text": "If parameters are adjusted to match a known frequency, that same match is not an independent validation. Compare with suitable independent evidence and retain the model’s domain of use." } ], "takeaway": "A plausible reconstruction is a documented hypothesis constrained by evidence, not a recovered certainty.", "boundary": "No new simulation, measured frequency or complete pipe reconstruction is supplied by this example.", "sources": [ { "label": "Cuntz Positiv · VAO 0.5.0-rc.2", "href": "https://doi.org/10.5281/zenodo.22151203", "detail": "Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release." }, { "label": "Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)", "detail": "Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here." } ], "expanded": false, "caseLabel": "Cuntz", "evidence": "Illustrative scenario" }, { "type": "example", "id": "cuntz-finite-elements", "title": "What does a finite-element pipe model actually calculate?", "concept": "Finite-element analysis divides a modeled domain into small connected elements and approximates the governing equations over that mesh. Its result depends on geometry, material or medium properties, and boundary conditions.", "scenario": "Imagine using a documented Cuntz pipe dimension as one input to a passive acoustic model. The 1281 mm observation alone does not describe the entire cavity or its excitation.", "steps": [ { "title": "Build an explicit domain", "text": "Describe the modeled interior geometry and distinguish measured dimensions from inferred ones. A display mesh of the organ case is not automatically a suitable acoustic domain." }, { "title": "Specify the physical question", "text": "A passive eigenmode calculation asks which patterns and frequencies the specified domain can support under its boundary assumptions. It is not a full simulation of air flow, pipe speech and self-sustained sound production." }, { "title": "Evaluate the approximation", "text": "Check numerical resolution and compare with suitable independent measurements. Refining a mesh can address numerical approximation while leaving uncertain geometry or inappropriate boundary assumptions unresolved." } ], "takeaway": "A numerical solution answers the equations and conditions supplied to it; interpretation requires checking whether those represent the research question.", "boundary": "This is a method explanation, not a new Cuntz finite-element result or a claim that the web model is acoustically validated.", "sources": [ { "label": "Cuntz Positiv · VAO 0.5.0-rc.2", "href": "https://doi.org/10.5281/zenodo.22151203", "detail": "Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release." }, { "label": "Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)", "detail": "Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here." }, { "label": "VAO Standard 0.5.0", "href": "https://doi.org/10.5281/zenodo.22214248", "detail": "The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2." } ], "expanded": false, "caseLabel": "Cuntz", "evidence": "Illustrative scenario" }, { "type": "heading", "id": "simplification", "text": "Simplification can remove the feature that matters" }, { "type": "p", "text": "A low polygon count is attractive for interactive playback, but visual economy and acoustic relevance do not always align. Section 8.5.1 reports that unweighted simplification below 50,000 polygons damaged features including labia, core gaps and cut-up edges in the investigated setting. A protected weighting of 100 belongs to that configuration; it is not a universal setting for every organ or reconstruction pipeline." }, { "type": "p", "text": "Retain a detailed research realization and derive a lighter presentation realization with a documented purpose. Check the features relevant to the question after simplification, not only the final file size. The two realizations can share an asset role while preserving their different bytes, derivations and intended uses. This makes a mobile visualization usable without silently replacing the geometric evidence." }, { "type": "heading", "id": "pamt", "text": "PAMT: a proposed architecture for spatial acoustics" }, { "type": "p", "text": "PAMT is presented as a conceptual architecture, not a field-validated room-acoustic product. The thesis discusses coupling geometric and wave-based methods because geometric propagation alone cannot represent all low-frequency modal behavior. The transition needs to depend on the room and frequency regime, with reference to the room’s Schroeder frequency, rather than a universal cutoff applied everywhere." }, { "type": "p", "text": "No in-situ sound-pressure measurement campaign is reported for PAMT in the dissertation. Its proposed field validation and uncertainty budgets remain prospective. This matters when selecting a tool: the architecture can guide research questions and implementation, but it does not supply measured accuracy for a visitor’s room. A published conceptual method, a working prototype and a calibrated acoustic model are different deliverables." }, { "type": "links", "items": [ { "label": "VAO-Pipe evaluation", "href": "https://doi.org/10.5281/zenodo.22663231", "detail": "Versioned report associated with the pipe modeling and evaluation work." }, { "label": "Three case studies", "href": "/notebooks/research/case-studies/", "detail": "See how geometric and acoustic assumptions affect interpretation." }, { "label": "Represent responses and spatial frames", "href": "/notebooks/vao/acoustics/", "detail": "Carry the assumptions into the object record." } ] } ], "sources": [ { "label": "MODAVIS Processor · module guide and package README", "detail": "Project documentation inspected on 26 September 2026; package 0.2.0, an unpublished development candidate. Used for current module responsibilities and limitations, not as a claim of public package availability." }, { "label": "Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)", "detail": "Dissertation submitted to Universität Leipzig, 11 September 2026. §5.12.6; §5.15.2; §§8.4.3 and 8.5.1, pp. 277–281. Page numbers refer to the printed manuscript pagination. The manuscript is not distributed by this website." }, { "label": "VAO-Pipe evaluation", "href": "https://doi.org/10.5281/zenodo.22663231", "detail": "Research report on procedural pipe geometry and passive pressure-acoustic evaluation." } ] }, "figures": {} } }