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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-XI-4-2026-69-2026</article-id>
<title-group>
<article-title>Reproducing Geospatial Crowdsourcing: How Consistent Is the Crowd?</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Collmar</surname>
<given-names>David</given-names>
<ext-link>https://orcid.org/0000-0003-0752-7633</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Walter</surname>
<given-names>Volker</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>Sörgel</surname>
<given-names>Uwe</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>Ullmann</surname>
<given-names>Roland</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Institute for Photogrammetry and Geoinformatics (ifp), University of Stuttgart, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>10</day>
<month>07</month>
<year>2026</year>
</pub-date>
<volume>XI-4-2026</volume>
<fpage>69</fpage>
<lpage>76</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 David Collmar 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/XI-4-2026/69/2026/isprs-annals-XI-4-2026-69-2026.html">This article is available from https://isprs-annals.copernicus.org/articles/XI-4-2026/69/2026/isprs-annals-XI-4-2026-69-2026.html</self-uri>
<self-uri xlink:href="https://isprs-annals.copernicus.org/articles/XI-4-2026/69/2026/isprs-annals-XI-4-2026-69-2026.pdf">The full text article is available as a PDF file from https://isprs-annals.copernicus.org/articles/XI-4-2026/69/2026/isprs-annals-XI-4-2026-69-2026.pdf</self-uri>
<abstract>
<p>This paper investigates the long-term consistency and reliability of paid geospatial crowdsourcing on the online platform Microworkers.com. Over a five-month period, we conducted three crowdsourcing campaigns, each representing a task typical for remote sensing, i.e., pixel classification, point selection, and geometric outline acquisition, to assess whether repeated worker participation enhances data quality and reproducibility. Beyond individual task performance, we examine the broader question of whether crowdsourcing campaigns can yield reproducible results over extended periods. Despite the large and heterogeneous workforce of Microworkers.com, a substantial share of tasks was completed by recurring workers who consistently outperformed one-time participants. Furthermore, across all campaigns, data quality remained largely stable, with only minor variability between epochs. Additionally performed statistical analyses confirm that reproducible outcomes are achievable, highlighting the potential of reliable and reproducible crowdsourcing results for geospatial data acquisition.</p>
</abstract>
<counts><page-count count="8"/></counts>
</article-meta>
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