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    <p>Hi gdal community,</p>
    <p>
      Is there a way to implement the <code class="notranslate">projective</code>
      transformation algorithm (Fig. 2) which is available in the QGIS
      georeferencer to the <code class="notranslate">gdalwarp</code>
      utility?</p>
    <p dir="auto">we developed a tool to process sidescan sonar
      (underwater acoustic imagery) data (open source, find the code
      here: <a href="https://github.com/sonoware/sidescantools"
        class="moz-txt-link-freetext">https://github.com/sonoware/sidescantools</a>).
      These are roughly three steps:</p>
    <ol dir="auto">
      <li>Find bottom line</li>
      <li>Do corrections for slant range & signal attenuation</li>
      <li>convert to image, slice image into small chunks and do
        chunk-wise georeferencing using gcps (script <a
href="https://github.com/sonoware/sidescantools/blob/main/sidescan_georeferencer.py">sidescan_georeferencer.py</a>)<br>
        The last step uses <code class="notranslate">gdal_translate</code>
        and gcps to georeference small chunks of the image and <code
          class="notranslate">gdalwarp</code> for the tranformation to
        geotiff. Right now we use <code class="notranslate">polynomial
          1</code> as transformation algorithm but this, as it preserves
        parallels, leaves gaps between the chunks (first pic). In QGIS,
        there is an option <code class="notranslate">projective</code>
        as tranformation algorithm (2nd pic), which does the trick but
        is not implemented in gdal? At least I haven't found it (if I've
        overseen something I'm terribly sorry for bothering!). I would
        love to help if I can.</li>
    </ol>
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