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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ISPRS-Archives</journal-id>
<journal-title-group>
<journal-title>ISPRS - 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-B2-2020-119-2020</article-id>
<title-group>
<article-title>IMPACT OF FLIGHT ALTITUDE ON UNMANNED AERIAL PHOTOGRAMMETRIC SURVEY OF THE SNOW HEIGHT ON MOUNT LEBANON</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Abou Chakra</surname>
<given-names>C.</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>Somma</surname>
<given-names>J.</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>Gascoin</surname>
<given-names>S.</given-names>

</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<ext-link>https://orcid.org/0000-0002-4996-6768</ext-link></contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fanise</surname>
<given-names>P.</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>Drapeau</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Laboratoire de Télédétection, Centre de Recherche en Environnement-Espace Méditerranée Orientale, Université Saint-Joseph, Beirut, Lebanon</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Arab Union of Surveyors, Beirut, Lebanon</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>CESBIO, Université de Toulouse, CNES/CNRS/INRA/IRD/UPS, Toulouse, France</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>119</fpage>
<lpage>125</lpage>
<permissions>
<copyright-statement>Copyright: © 2020 C. Abou Chakra 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/isprs-archives-XLIII-B2-2020-119-2020.html">This article is available from https://isprs-archives.copernicus.org/articles/isprs-archives-XLIII-B2-2020-119-2020.html</self-uri>
<self-uri xlink:href="https://isprs-archives.copernicus.org/articles/isprs-archives-XLIII-B2-2020-119-2020.pdf">The full text article is available as a PDF file from https://isprs-archives.copernicus.org/articles/isprs-archives-XLIII-B2-2020-119-2020.pdf</self-uri>
<abstract>
<p>&lt;p&gt;In Lebanon, the seasonal snowpack is poorly monitored despite its importance for water resource supply. The snow accumulates on Mount Lebanon in karstic depressions named “sinkholes.” It is important to monitor the evolution of the snow height inside those “sinkholes”, because of their key role as “containers” for seasonal snow. UAV photogrammetry is a major technological breakthrough which allows an accurate monitoring of the snow height. Because the impact of flight parameters on snow height retrievals is not well documented yet, this research aims to evaluate the impact of UAV flight altitude on the resolution and accuracy of the resulting orthomosaic and DSM. The flight missions were done using the Phantom DJI which generated five DSMs. These are validated using total station measurements.&lt;/p&gt;&lt;p&gt;The results indicate that the snow DSMs can be retrieved by adopting a resolution of 8 to 84 cm, a point density between 1.43 and 153 points/sqm and a RMSE of 13 to 41 cm. The testing was done using an elevation varying between 50 and 500 m. The results will be compared to total station observations. These results allow the user to choose the suitable flight altitude for required resolution and points density. We suggest that a flight altitude of 100 m is sufficient for the survey of the snow cover elevation.&lt;/p&gt;</p>
</abstract>
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