<liclass="toctree-l4"><aclass="reference internal"href="../installation/#step-1-check-virtualization-support">Krok 1. Zkontrolujte podporu virtualizace</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../installation/#step-2-install-requirements">Krok 2. Požadavky na instalaci</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../installation/#step-3-check-memory-and-cpu-allocation">Krok 3. Zkontrolujte přidělení paměti a procesoru</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../installation/#step-4-download-webodm">Krok 4. Stáhněte si WebODM</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../installation/#step-2-check-additional-requirements">Krok 2. Zkontrolujte další požadavky</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../installation/#step-3-download-and-launch-webodm">Krok 3. Stažení a spuštění WebODM</a></li>
</ul>
</li>
</ul>
</li>
<liclass="toctree-l2"><aclass="reference internal"href="../installation/#basic-commands-and-troubleshooting">Základní příkazy a řešení potíží</a></li>
<liclass="toctree-l2"><aclass="reference internal"href="../installation/#hello-webodm">Dobrý den, WebODM!</a><ul>
<liclass="toctree-l3"><aclass="reference internal"href="../installation/#running-on-more-than-one-machine">Spuštění na více než jednom počítači</a></li>
<liclass="toctree-l2"><aclass="reference internal"href="../tutorials/#creating-high-quality-orthophotos">Vytváření vysoce kvalitních ortofotomap</a></li>
<liclass="toctree-l2"><aclass="reference internal"href="../tutorials/#using-docker">Použití aplikace Docker</a><ul>
<liclass="toctree-l3"><aclass="reference internal"href="../tutorials/#listing-docker-machines">Výpis strojů Docker</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../tutorials/#accessing-logs-on-the-instance">Přístup k protokolům instance</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../tutorials/#command-line-access-to-instances">Přístup k instancím z příkazového řádku</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../tutorials/#cleaning-up-after-docker">Úklid po Dockeru</a></li>
<liclass="toctree-l2"><aclass="reference internal"href="../tutorials/#using-odm-from-low-bandwidth-location">Použití ODM z místa s nízkou šířkou pásma</a><ul>
<liclass="toctree-l3"><aclass="reference internal"href="../tutorials/#what-is-this-and-who-is-it-for">Co to je a pro koho je to určeno?</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../tutorials/#prep-data-and-project">Příprava dat a projektu</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../tutorials/#resize-droplet-pull-pin-run-away">Resize droplet, pull pin, run away</a></li>
<liclass="toctree-l4"><aclass="reference internal"href="../tutorials/#after-it-finishes-assuming-you-survive-that-long">Po jeho skončení (za předpokladu, že přežijete tak dlouho)</a></li>
</ul>
</li>
</ul>
</li>
<liclass="toctree-l2"><aclass="reference internal"href="../tutorials/#using-potree-3d-viewer-module-on-webodm">Použití modulu Potree 3D viewer na WebODM</a><ul>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/auto-boundary/#what-is-auto-boundary">Co je automatická hranice?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/auto-boundary/#when-is-auto-boundary-helpful">Kdy je automatická hranice užitečná?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/auto-boundary/#why-would-one-use-auto-boundary">Proč by měl někdo používat automatické ohraničení?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/boundary/#what-is-boundary-geojson">Co je to Hranice [GeoJSON]?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/boundary/#when-is-boundary-geojson-appropriate">Kdy je vhodné použít Hranice [GeoJSON]?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/boundary/#why-would-one-use-boundary-geojson">Proč by měl někdo použít Hranice [GeoJSON]?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/boundary/#how-would-one-create-boundary-geojson">Jak se vytváří Hranice [GeoJSON]?</a><ul>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/build-overviews/#what-are-overviews">What Are Overviews?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/build-overviews/#when-are-overviews-appropriate">When are Overviews appropriate?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/build-overviews/#why-would-one-use-overviews">Why would one use Overviews?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/camera-lens/#what-are-camera-lens-models">Co jsou modely objektivů fotoaparátů?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/camera-lens/#when-are-manual-selections-appropriate">Kdy je vhodný ruční výběr?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../arguments/camera-lens/#why-would-one-use-a-particular-camera-lens-model">Proč používat určitý model objektivu fotoaparátu?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../large/#getting-started-with-distributed-split-merge">Getting Started with Distributed Split-Merge</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../large/#understanding-the-cluster">Understanding the Cluster</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../large/#accessing-the-logs">Accessing the Logs</a></li>
<liclass="toctree-l2"><aclass="reference internal"href="../multispectral/#creating-orthophotos-from-multispectral-data">Creating Orthophotos from Multispectral Data</a></li>
<liclass="toctree-l2"><aclass="reference internal"href="../multispectral/#workflows-for-non-supported-sensors">Workflows for Non-supported Sensors</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../faq/#can-i-process-two-or-more-orthophoto-geotiffs-to-stitch-them-together">Mohu zpracovat dva nebo více ortofotografických souborů GeoTIFF a spojit je dohromady?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../faq/#the-software-is-not-using-all-of-my-cpu-cores-memory-gpu-all-of-the-times-is-it-normal">The software is not using all of my CPU cores / memory / GPU all of the times. Is it normal?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../faq/#if-i-use-the-native-version-of-the-software-how-can-i-allocate-more-resources-for-processing">If I use the native version of the software, how can I allocate more resources for processing?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../faq/#i-want-to-build-a-commercial-application-that-includes-odm-do-i-need-a-commercial-license">Chci vytvořit komerční aplikaci, která zahrnuje ODM. Potřebuji komerční licenci?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../faq/#are-there-other-licensing-options-aside-from-the-agplv3">Existují kromě licence AGPLv3 i jiné možnosti licencování?</a></li>
<liclass="toctree-l3"><aclass="reference internal"href="../faq/#your-computer-is-running-out-of-memory-what-can-you-do">Your computer is running out of memory, what can you do?</a></li>
<h1>Ground Control Points<aclass="headerlink"href="#ground-control-points"title="Permalink to this heading"></a></h1>
<p>Ground control points are useful for correcting distortions in the data and referencing the data to know coordinate systems.</p>
<p>A Ground Control Point (GCP) is a position measurement made on the ground, typically using a high precision GPS. (Toffanin 2019)</p>
<p>Ground control points can be set existing structures like pavement corners, lines on a parking lot or contrasting color floor tiles, otherwise can be set using targets placed on the ground.</p>
<p>Targets can be purchased or build with an ample variety of materials ranging from bucket lids to floor tiles.</p>
<h2>Recommended practices for GCP setting<aclass="headerlink"href="#recommended-practices-for-gcp-setting"title="Permalink to this heading"></a></h2>
<p>Keep ground control points visible for all camera locations. Consider the expected ground sampling distance, illumination, vegetation, buildings and all the existing obstacles.</p>
<p>Procure an evenly horizontal distribution of the GCPs within the project, covering high and low elevations. A minimum of 5 GCP works for most of the jobs, and for larger projects 8 – 10 are sufficient. Locate some points near the corners and others in the center, considering that GCP spacing should be larger than the image footprint so that you can’t see more than one GCP in a single image.</p>
<p>In order to ensure each GCP are found in at least 5 images, separate the points 10 to 30 meters from the perimeter of the project. This distance is dependent of the overlapping, so increasing overlapping should reduce the required distance from the perimeter.</p>
</section>
<sectionid="gcp-file-format">
<h2>GCP file format<aclass="headerlink"href="#gcp-file-format"title="Permalink to this heading"></a></h2>
<p>The format of the GCP file is simple.</p>
<blockquote>
<div><ulclass="simple">
<li><p>The first line should contain the name of the projection used for the geo coordinates. This can be specified either as a PROJ string (e.g. <codeclass="docutils literal notranslate"><spanclass="pre">+proj=utm</span><spanclass="pre">+zone=10</span><spanclass="pre">+ellps=WGS84</span><spanclass="pre">+datum=WGS84</span><spanclass="pre">+units=m</span><spanclass="pre">+no_defs</span></code>), EPSG code (e.g. <codeclass="docutils literal notranslate"><spanclass="pre">EPSG:4326</span></code>) or as a <codeclass="docutils literal notranslate"><spanclass="pre">WGS84</span><spanclass="pre">UTM</span><spanclass="pre"><zone>[N|S]</span></code> value (eg. <codeclass="docutils literal notranslate"><spanclass="pre">WGS84</span><spanclass="pre">UTM</span><spanclass="pre">16N</span></code>)</p></li>
<li><p>Subsequent lines are the X, Y & Z coordinates, your associated pixels, the image filename and optional extra fields, separated by tabs or spaces:</p></li>
<li><p>Elevation values can be set to „NaN“ to indicate no value</p></li>
<li><p>The 7th column (optional) typically contains the label of the GCP.</p></li>
<p>If you supply a GCP file called <codeclass="docutils literal notranslate"><spanclass="pre">gcp_list.txt</span></code> then ODM will automatically detect it. If it has another name you can specify using <codeclass="docutils literal notranslate"><spanclass="pre">--gcp</span><spanclass="pre"><path></span></code>. If you have a gcp file and want to do georeferencing with exif instead, then you can specify <codeclass="docutils literal notranslate"><spanclass="pre">--use-exif</span></code>. If you have high precision GPS measurements in your images (RTK) and want to use that information along with a gcp file, you can specify <codeclass="docutils literal notranslate"><spanclass="pre">--force-gps</span></code>.</p>
<p><aclass="reference external"href="http://diydrones.com/profiles/blogs/ground-control-points-gcps-for-aerial-photography">This post has some information about placing Ground Control Targets before a flight</a>, but if you already have images, you can find your own points in the images post facto. It’s important that you find high-contrast objects that are found in <strong>at least</strong> 3 photos, and that you find a minimum of 5 objects.</p>
<p>Sharp corners are good picks for GCPs. You should also place/find the GCPs evenly around your survey area.</p>
<p>The <codeclass="docutils literal notranslate"><spanclass="pre">gcp_list.txt</span></code> file must be created in the base of your project folder.</p>
<p>For good results your file should have a minimum of 15 lines after the header (5 points with 3 images to each point).</p>
</section>
<sectionid="user-interfaces">
<h2>User Interfaces<aclass="headerlink"href="#user-interfaces"title="Permalink to this heading"></a></h2>
<p>You can use one of two user interfaces for creating GCP files:</p>
<h3>POSM GCPi<aclass="headerlink"href="#id1"title="Permalink to this heading"></a></h3>
<p>The POSM GCPi is loaded by default on WebODM. An example is available at <aclass="reference external"href="http://demo.webodm.org/plugins/posm-gcpi/">the WebODM Demo</a>. To use this with known ground control XYZ values, one would do the following:</p>
<p>Create a GCP list that only includes gcp name (this is the label that will be seen in the GCP interface), x, y, and z, with a header with a proj4 string of your GCPs (make sure they are in a planar coordinate system, such as UTM. It should look something like this:</p>
<p>Then one can load this GCP list into the interface, load the images, and place each of the GCPs in the image.</p>
</section>
<sectionid="id2">
<h3>GCP Editor Pro<aclass="headerlink"href="#id2"title="Permalink to this heading"></a></h3>
<p>This app needs to be installed separately or can be loaded as a WebODM plugin from <aclass="reference external"href="https://github.com/uav4geo/GCPEditorPro">https://github.com/uav4geo/GCPEditorPro</a></p>
<p>Create a CSV file that includes the gcp name, northing, easting and elevation.</p>
<p>Then import the CSV from the main screen and type <codeclass="docutils literal notranslate"><spanclass="pre">+proj=utm</span><spanclass="pre">+zone=37</span><spanclass="pre">+south</span><spanclass="pre">+ellps=WGS84</span><spanclass="pre">+datum=WGS84</span><spanclass="pre">+units=m</span><spanclass="pre">+no_defs</span></code> in the <codeclass="docutils literal notranslate"><spanclass="pre">EPSG/PROJ</span></code> box.</p>
<p>The following screen will display a map from where to select the GCPs to tag and import the respective images.</p>
</section>
</section>
<sectionid="references">
<h2>References<aclass="headerlink"href="#references"title="Permalink to this heading"></a></h2>
<p><aclass="reference external"href="https://github.com/opendronemap/docs#how-to-make-your-first-contribution">Learn to edit</a> and help improve <aclass="reference external"href="https://github.com/OpenDroneMap/docs/blob/publish/source/gcp.rst">this page</a>!</p>
