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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ISPRS-Annals</journal-id>
<journal-title-group>
<journal-title>ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences</journal-title>
<abbrev-journal-title abbrev-type="publisher">ISPRS-Annals</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">2194-9050</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/isprs-annals-XII-4-W2-2026-49-2026</article-id>
<title-group>
<article-title>A Workflow for Interactive Visualization of Urban CFD Data in Unreal Engine and via Web Streaming</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Eleftheriou</surname>
<given-names>Orfeas</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Naserentin</surname>
<given-names>Vasilis</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Pantusheva</surname>
<given-names>Mariya</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Petrova-Antonova</surname>
<given-names>Dessislava</given-names>
<ext-link>https://orcid.org/0000-0002-9920-8877</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Logg</surname>
<given-names>Anders</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Mathematical Sciences, Chalmers University of Technology, 412 969 Gothenburg, Sweden</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Electrical &amp; Computer Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>GATE Institute, Sofia 1164, Bulgaria</addr-line>
</aff>
<pub-date pub-type="epub">
<day>28</day>
<month>09</month>
<year>2026</year>
</pub-date>
<volume>XII-4/W2-2026</volume>
<fpage>49</fpage>
<lpage>56</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Orfeas Eleftheriou et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://isprs-annals.copernicus.org/articles/XII-4-W2-2026/49/2026/isprs-annals-XII-4-W2-2026-49-2026.html">This article is available from https://isprs-annals.copernicus.org/articles/XII-4-W2-2026/49/2026/isprs-annals-XII-4-W2-2026-49-2026.html</self-uri>
<self-uri xlink:href="https://isprs-annals.copernicus.org/articles/XII-4-W2-2026/49/2026/isprs-annals-XII-4-W2-2026-49-2026.pdf">The full text article is available as a PDF file from https://isprs-annals.copernicus.org/articles/XII-4-W2-2026/49/2026/isprs-annals-XII-4-W2-2026-49-2026.pdf</self-uri>
<abstract>
<p>To analyze current and predict future conditions, smart-city planning relies on physics-based simulations to support sustainable design, climate adaptation, and citizen engagement. Yet, the analysis results often remain locked inside specialist tools and static plots that are difficult for non-experts to access and interpret. As part of a broader framework developed for scientific results visualization in an urban context, this paper presents a semi-automated workflow for transforming urban Computational Fluid Dynamics (CFD) outputs into interactive 3D visualizations using Unreal Engine and a web-based streaming application. The feasibility of the workflow is demonstrated through a wind-flow case study of an area in central Sofia, Bulgaria. The proposed approach covers the complete process, from problem formulation and data preparation through simulation execution, results processing, and integration into Unreal Engine. The visualization component is implemented through a modular actor-based architecture that supports both point-based and trajectory-based flow representations, which can be flexibly combined and interactively modified within the scene. Additionally, the visualization system is deployed through Pixel Streaming, providing a practical and viable way to transform complex CFD data into exploratory tools that are accessible to a wide range of urban stakeholders.</p>
</abstract>
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