<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "https://jats.nlm.nih.gov/nlm-dtd/publishing/3.0/journalpublishing3.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="3.0" xml:lang="en">
<front>
<journal-meta>
<journal-id journal-id-type="publisher">ISPRS-Archives</journal-id>
<journal-title-group>
<journal-title>The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences</journal-title>
<abbrev-journal-title abbrev-type="publisher">ISPRS-Archives</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">2194-9034</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-archives-XLIII-B2-2020-949-2020</article-id>
<title-group>
<article-title>3D RECONSTRUCTION AND MESH OPTIMIZATION OF UNDERWATER SPACES FOR VIRTUAL REALITY</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>El Saer</surname>
<given-names>A.</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>Stentoumis</surname>
<given-names>C.</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>Kalisperakis</surname>
<given-names>I.</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>Grammatikopoulos</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Nomikou</surname>
<given-names>P.</given-names>
<ext-link>https://orcid.org/0000-0001-8842-9730</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>Vlasopoulos</surname>
<given-names>O.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>up2metric P.C., 11521, Athens, Greece</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Dept. of Surveying and Geoinformatics Engineering, University of West Attica, 12243, Egaleo, Greece</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Dept. of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15784, Athens, Greece</addr-line>
</aff>
<pub-date pub-type="epub">
<day>12</day>
<month>08</month>
<year>2020</year>
</pub-date>
<volume>XLIII-B2-2020</volume>
<fpage>949</fpage>
<lpage>956</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2020 A. El Saer et al.</copyright-statement>
<copyright-year>2020</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-archives.copernicus.org/articles/XLIII-B2-2020/949/2020/isprs-archives-XLIII-B2-2020-949-2020.html">This article is available from https://isprs-archives.copernicus.org/articles/XLIII-B2-2020/949/2020/isprs-archives-XLIII-B2-2020-949-2020.html</self-uri>
<self-uri xlink:href="https://isprs-archives.copernicus.org/articles/XLIII-B2-2020/949/2020/isprs-archives-XLIII-B2-2020-949-2020.pdf">The full text article is available as a PDF file from https://isprs-archives.copernicus.org/articles/XLIII-B2-2020/949/2020/isprs-archives-XLIII-B2-2020-949-2020.pdf</self-uri>
<abstract>
<p>In this contribution, we propose a versatile image-based methodology for 3D reconstructing underwater scenes of high fidelity and integrating them into a virtual reality environment. Typically, underwater images suffer from colour degradation (blueish images) due to the propagation of light through water, which is a more absorbing medium than air, as well as the scattering of light on suspended particles. Other factors, such as artificial lights, also, diminish the quality of images and, thus, the quality of the image-based 3D reconstruction. Moreover, degraded images have a direct impact on the user perception of the virtual environment, due to geometric and visual degenerations. Here, it is argued that these can be mitigated by image pre-processing algorithms and specialized filters. The impact of different filtering techniques on images is evaluated, in order to eliminate colour degradation and mismatches in the image sequences. The methodology in this work consists of five sequential pre-processes; &lt;i&gt;saturation enhancement&lt;/i&gt;, &lt;i&gt;haze reduction&lt;/i&gt;, and &lt;i&gt;Rayleigh distribution adaptation&lt;/i&gt;, to de-haze the images, &lt;i&gt;global histogram matching&lt;/i&gt; to minimize differences among images of the dataset, and &lt;i&gt;image sharpening&lt;/i&gt; to strengthen the edges of the scene. The 3D reconstruction of the models is based on open-source structure-from-motion software. The models are optimized for virtual reality through &lt;i&gt;mesh simplification&lt;/i&gt;, &lt;i&gt;physically based rendering&lt;/i&gt; texture maps baking, and &lt;i&gt;level-of-details&lt;/i&gt;. The results of the proposed methodology are qualitatively evaluated on image datasets captured in the seabed of Santorini island in Greece, using a ROV platform.</p>
</abstract>
<counts><page-count count="8"/></counts>
</article-meta>
</front>
<body/>
<back>
</back>
</article>