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This acoustic sensor produces a cross-sectional map of the field-of-view using only one speaker\/microphone pair. While it is challenging to have enough spatial diversity of signal with a single omnidirectional source, we leverage sound\u2019s interaction with small structures to create a 3D-printed passive filter, called a stencil, that can project spatially coded signals on a region at a fine granularity. The system receives a linear combination of the reflections from nearby objects and applies a novel power-aware depth-map reconstruction algorithm. The algorithm first estimates the approximate locations of the objects in the scene and then iteratively applies fractional multi-resolution inversion.\n                    <jats:italic toggle=\"yes\">SPiDR<\/jats:italic>\n                    consumes only\n                    <jats:inline-formula>\n                      <mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"inline\">\n                        <mml:mrow>\n                          <mml:mn>10<\/mml:mn>\n                          <mml:mi>m<\/mml:mi>\n                          <mml:mi>W<\/mml:mi>\n                        <\/mml:mrow>\n                      <\/mml:math>\n                    <\/jats:inline-formula>\n                    of power to generate a depth-map in real-world scenario with over 80% structural similarity score with the scene.\n                  <\/jats:p>","DOI":"10.1145\/3772712","type":"journal-article","created":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T18:28:01Z","timestamp":1771612081000},"page":"95-106","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["SPiDR: Microstructure-Assisted Vision for Ubiquitous Tiny Robots"],"prefix":"10.1145","volume":"69","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4437-9457","authenticated-orcid":false,"given":"Yang","family":"Bai","sequence":"first","affiliation":[{"name":"University of Maryland College Park, College Park, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8585-0180","authenticated-orcid":false,"given":"Nakul","family":"Garg","sequence":"additional","affiliation":[{"name":"University of Maryland College Park, College Park, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5261-7780","authenticated-orcid":false,"given":"Nirupam","family":"Roy","sequence":"additional","affiliation":[{"name":"University of Maryland College Park, College Park, Maryland, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"320","published-online":{"date-parts":[[2026,2,27]]},"reference":[{"key":"e_1_3_1_2_2","volume-title":"Modern Radar System Analysis","author":"Barton D.K.","year":"1988","unstructured":"Barton, D.K. 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