mirror of
https://github.com/bellingcat/RS4OSINT.git
synced 2026-06-11 13:08:36 +03:00
536 lines
25 KiB
HTML
536 lines
25 KiB
HTML
<!DOCTYPE html>
|
||
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
|
||
|
||
<meta charset="utf-8">
|
||
<meta name="generator" content="quarto-1.2.269">
|
||
|
||
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
|
||
|
||
|
||
<title>Google Earth Engine for OSINT - 3 Algorithms</title>
|
||
<style>
|
||
code{white-space: pre-wrap;}
|
||
span.smallcaps{font-variant: small-caps;}
|
||
div.columns{display: flex; gap: min(4vw, 1.5em);}
|
||
div.column{flex: auto; overflow-x: auto;}
|
||
div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
|
||
ul.task-list{list-style: none;}
|
||
ul.task-list li input[type="checkbox"] {
|
||
width: 0.8em;
|
||
margin: 0 0.8em 0.2em -1.6em;
|
||
vertical-align: middle;
|
||
}
|
||
</style>
|
||
|
||
|
||
<script src="site_libs/quarto-nav/quarto-nav.js"></script>
|
||
<script src="site_libs/quarto-nav/headroom.min.js"></script>
|
||
<script src="site_libs/clipboard/clipboard.min.js"></script>
|
||
<script src="site_libs/quarto-search/autocomplete.umd.js"></script>
|
||
<script src="site_libs/quarto-search/fuse.min.js"></script>
|
||
<script src="site_libs/quarto-search/quarto-search.js"></script>
|
||
<meta name="quarto:offset" content="./">
|
||
<link href="./ch4.html" rel="next">
|
||
<link href="./ch2.html" rel="prev">
|
||
<script src="site_libs/quarto-html/quarto.js"></script>
|
||
<script src="site_libs/quarto-html/popper.min.js"></script>
|
||
<script src="site_libs/quarto-html/tippy.umd.min.js"></script>
|
||
<script src="site_libs/quarto-html/anchor.min.js"></script>
|
||
<link href="site_libs/quarto-html/tippy.css" rel="stylesheet">
|
||
<link href="site_libs/quarto-html/quarto-syntax-highlighting.css" rel="stylesheet" class="quarto-color-scheme" id="quarto-text-highlighting-styles">
|
||
<link href="site_libs/quarto-html/quarto-syntax-highlighting-dark.css" rel="stylesheet" class="quarto-color-scheme quarto-color-alternate" id="quarto-text-highlighting-styles">
|
||
<script src="site_libs/bootstrap/bootstrap.min.js"></script>
|
||
<link href="site_libs/bootstrap/bootstrap-icons.css" rel="stylesheet">
|
||
<link href="site_libs/bootstrap/bootstrap.min.css" rel="stylesheet" class="quarto-color-scheme" id="quarto-bootstrap" data-mode="light">
|
||
<link href="site_libs/bootstrap/bootstrap-dark.min.css" rel="stylesheet" class="quarto-color-scheme quarto-color-alternate" id="quarto-bootstrap" data-mode="dark">
|
||
<script id="quarto-search-options" type="application/json">{
|
||
"location": "sidebar",
|
||
"copy-button": false,
|
||
"collapse-after": 3,
|
||
"panel-placement": "start",
|
||
"type": "textbox",
|
||
"limit": 20,
|
||
"language": {
|
||
"search-no-results-text": "No results",
|
||
"search-matching-documents-text": "matching documents",
|
||
"search-copy-link-title": "Copy link to search",
|
||
"search-hide-matches-text": "Hide additional matches",
|
||
"search-more-match-text": "more match in this document",
|
||
"search-more-matches-text": "more matches in this document",
|
||
"search-clear-button-title": "Clear",
|
||
"search-detached-cancel-button-title": "Cancel",
|
||
"search-submit-button-title": "Submit"
|
||
}
|
||
}</script>
|
||
|
||
|
||
</head>
|
||
|
||
<body class="nav-sidebar floating">
|
||
|
||
<div id="quarto-search-results"></div>
|
||
<header id="quarto-header" class="headroom fixed-top">
|
||
<nav class="quarto-secondary-nav" data-bs-toggle="collapse" data-bs-target="#quarto-sidebar" aria-controls="quarto-sidebar" aria-expanded="false" aria-label="Toggle sidebar navigation" onclick="if (window.quartoToggleHeadroom) { window.quartoToggleHeadroom(); }">
|
||
<div class="container-fluid d-flex justify-content-between">
|
||
<h1 class="quarto-secondary-nav-title"><span class="chapter-number">3</span> <span class="chapter-title">Algorithms</span></h1>
|
||
<button type="button" class="quarto-btn-toggle btn" aria-label="Show secondary navigation">
|
||
<i class="bi bi-chevron-right"></i>
|
||
</button>
|
||
</div>
|
||
</nav>
|
||
</header>
|
||
<!-- content -->
|
||
<div id="quarto-content" class="quarto-container page-columns page-rows-contents page-layout-article">
|
||
<!-- sidebar -->
|
||
<nav id="quarto-sidebar" class="sidebar collapse sidebar-navigation floating overflow-auto">
|
||
<div class="pt-lg-2 mt-2 text-left sidebar-header sidebar-header-stacked">
|
||
<a href="./index.html" class="sidebar-logo-link">
|
||
<img src="./logo_white.png" alt="" class="sidebar-logo py-0 d-lg-inline d-none">
|
||
</a>
|
||
<div class="sidebar-title mb-0 py-0">
|
||
<a href="./">Google Earth Engine for OSINT</a>
|
||
<div class="sidebar-tools-main tools-wide">
|
||
<a href="https://github.com/oballinger/GEE_OSINT/" title="Source Code" class="sidebar-tool px-1"><i class="bi bi-github"></i></a>
|
||
<a href="" title="Download" id="sidebar-tool-dropdown-0" class="sidebar-tool dropdown-toggle px-1" data-bs-toggle="dropdown" aria-expanded="false"><i class="bi bi-download"></i></a>
|
||
<ul class="dropdown-menu" aria-labelledby="sidebar-tool-dropdown-0">
|
||
<li>
|
||
<a class="dropdown-item sidebar-tools-main-item" href="./Google-Earth-Engine-for-OSINT.pdf">
|
||
<i class="bi bi-bi-file-pdf pe-1"></i>
|
||
Download PDF
|
||
</a>
|
||
</li>
|
||
<li>
|
||
<a class="dropdown-item sidebar-tools-main-item" href="./Google-Earth-Engine-for-OSINT.epub">
|
||
<i class="bi bi-bi-journal pe-1"></i>
|
||
Download ePub
|
||
</a>
|
||
</li>
|
||
</ul>
|
||
<a href="" title="Share" id="sidebar-tool-dropdown-1" class="sidebar-tool dropdown-toggle px-1" data-bs-toggle="dropdown" aria-expanded="false"><i class="bi bi-share"></i></a>
|
||
<ul class="dropdown-menu" aria-labelledby="sidebar-tool-dropdown-1">
|
||
<li>
|
||
<a class="dropdown-item sidebar-tools-main-item" href="https://twitter.com/intent/tweet?url=|url|">
|
||
<i class="bi bi-bi-twitter pe-1"></i>
|
||
Twitter
|
||
</a>
|
||
</li>
|
||
<li>
|
||
<a class="dropdown-item sidebar-tools-main-item" href="https://www.facebook.com/sharer/sharer.php?u=|url|">
|
||
<i class="bi bi-bi-facebook pe-1"></i>
|
||
Facebook
|
||
</a>
|
||
</li>
|
||
</ul>
|
||
<a href="" class="quarto-color-scheme-toggle sidebar-tool" onclick="window.quartoToggleColorScheme(); return false;" title="Toggle dark mode"><i class="bi"></i></a>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div class="mt-2 flex-shrink-0 align-items-center">
|
||
<div class="sidebar-search">
|
||
<div id="quarto-search" class="" title="Search"></div>
|
||
</div>
|
||
</div>
|
||
<div class="sidebar-menu-container">
|
||
<ul class="list-unstyled mt-1">
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./index.html" class="sidebar-item-text sidebar-link">Introduction</a>
|
||
</div>
|
||
</li>
|
||
<li class="sidebar-item sidebar-item-section">
|
||
<div class="sidebar-item-container">
|
||
<a class="sidebar-item-text sidebar-link text-start" data-bs-toggle="collapse" data-bs-target="#quarto-sidebar-section-1" aria-expanded="true">Learning</a>
|
||
<a class="sidebar-item-toggle text-start" data-bs-toggle="collapse" data-bs-target="#quarto-sidebar-section-1" aria-expanded="true">
|
||
<i class="bi bi-chevron-right ms-2"></i>
|
||
</a>
|
||
</div>
|
||
<ul id="quarto-sidebar-section-1" class="collapse list-unstyled sidebar-section depth1 show">
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./ch1.html" class="sidebar-item-text sidebar-link"><span class="chapter-number">1</span> <span class="chapter-title">Data Acquisition</span></a>
|
||
</div>
|
||
</li>
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./ch2.html" class="sidebar-item-text sidebar-link"><span class="chapter-number">2</span> <span class="chapter-title">Remote Sensing</span></a>
|
||
</div>
|
||
</li>
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./ch3.html" class="sidebar-item-text sidebar-link active"><span class="chapter-number">3</span> <span class="chapter-title">Algorithms</span></a>
|
||
</div>
|
||
</li>
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./ch4.html" class="sidebar-item-text sidebar-link"><span class="chapter-number">4</span> <span class="chapter-title">Application Development</span></a>
|
||
</div>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
<li class="sidebar-item sidebar-item-section">
|
||
<div class="sidebar-item-container">
|
||
<a class="sidebar-item-text sidebar-link text-start" data-bs-toggle="collapse" data-bs-target="#quarto-sidebar-section-2" aria-expanded="true">Case Studies</a>
|
||
<a class="sidebar-item-toggle text-start" data-bs-toggle="collapse" data-bs-target="#quarto-sidebar-section-2" aria-expanded="true">
|
||
<i class="bi bi-chevron-right ms-2"></i>
|
||
</a>
|
||
</div>
|
||
<ul id="quarto-sidebar-section-2" class="collapse list-unstyled sidebar-section depth1 show">
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./SyriaNTL.html" class="sidebar-item-text sidebar-link">War at Night</a>
|
||
</div>
|
||
</li>
|
||
<li class="sidebar-item">
|
||
<div class="sidebar-item-container">
|
||
<a href="./RojavaRefineries.html" class="sidebar-item-text sidebar-link">Refinery Detection</a>
|
||
</div>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
</ul>
|
||
</div>
|
||
</nav>
|
||
<!-- margin-sidebar -->
|
||
<div id="quarto-margin-sidebar" class="sidebar margin-sidebar">
|
||
<nav id="TOC" role="doc-toc" class="toc-active">
|
||
<h2 id="toc-title">Table of contents</h2>
|
||
|
||
<ul>
|
||
<li><a href="#remote_sensing" id="toc-remote_sensing" class="nav-link active" data-scroll-target="#remote_sensing"><span class="toc-section-number">3.1</span> Multispectral Remote Sensing</a>
|
||
<ul class="collapse">
|
||
<li><a href="#spatial-resolution" id="toc-spatial-resolution" class="nav-link" data-scroll-target="#spatial-resolution"><span class="toc-section-number">3.1.1</span> Spatial Resolution</a></li>
|
||
<li><a href="#spectral-resolution" id="toc-spectral-resolution" class="nav-link" data-scroll-target="#spectral-resolution"><span class="toc-section-number">3.1.2</span> Spectral Resolution</a></li>
|
||
<li><a href="#temporal-resolution" id="toc-temporal-resolution" class="nav-link" data-scroll-target="#temporal-resolution"><span class="toc-section-number">3.1.3</span> Temporal Resolution</a></li>
|
||
</ul></li>
|
||
</ul>
|
||
<div class="toc-actions"><div><i class="bi bi-github"></i></div><div class="action-links"><p><a href="https://github.com/oballinger/GEE_OSINT/edit/main/ch3.qmd" class="toc-action">Edit this page</a></p></div></div></nav>
|
||
</div>
|
||
<!-- main -->
|
||
<main class="content" id="quarto-document-content">
|
||
|
||
<header id="title-block-header" class="quarto-title-block default">
|
||
<div class="quarto-title">
|
||
<h1 class="title"><span id="sec-algorithms" class="quarto-section-identifier d-none d-lg-block"><span class="chapter-number">3</span> <span class="chapter-title">Algorithms</span></span></h1>
|
||
</div>
|
||
|
||
|
||
|
||
<div class="quarto-title-meta">
|
||
|
||
|
||
|
||
|
||
</div>
|
||
|
||
|
||
</header>
|
||
|
||
<section id="remote_sensing" class="level2" data-number="3.1">
|
||
<h2 data-number="3.1" class="anchored" data-anchor-id="remote_sensing"><span class="header-section-number">3.1</span> Multispectral Remote Sensing</h2>
|
||
<p>There are three spatial, spectral, and temporal.</p>
|
||
<section id="spatial-resolution" class="level3" data-number="3.1.1">
|
||
<h3 data-number="3.1.1" class="anchored" data-anchor-id="spatial-resolution"><span class="header-section-number">3.1.1</span> Spatial Resolution</h3>
|
||
<p>Spatial resolution governs how “sharp” an image looks. The Google Maps satellite basemap, for example, is really sharp Most of the optical imagery that is freely available has relatively low spatial resolution (it looks more grainy than, for example, the Google satellite basemap),</p>
|
||
<p><img src="./images/Landsat.png" class="img-fluid"> <img src="./images/Sentinel2.png" class="img-fluid"> <img src="./images/Maxar.png" class="img-fluid"></p>
|
||
<p><img src="./images/kh11.png" class="img-fluid"></p>
|
||
</section>
|
||
<section id="spectral-resolution" class="level3" data-number="3.1.2">
|
||
<h3 data-number="3.1.2" class="anchored" data-anchor-id="spectral-resolution"><span class="header-section-number">3.1.2</span> Spectral Resolution</h3>
|
||
<p>What open source imagery lacks in spatial resolution it often makes up for with <em>spectral</em> resolution. Really sharp imagery from MAXAR, for example, collects</p>
|
||
<p>Different materials reflect light differently. An apple absorbs shorter wavelengths (e.g. blue and green), and reflects longer wavelengths (red). Our eyes use that information– the color– to distinguish between different objects. But our eyes can only see a relatively small sliver of the electromagnetic spectrum covering blue, yellow, and red; we can’t see UV or infrared wavelengths, for example, though the extent to which different materials reflect or absorb these wavelengths is just as useful for distinguishing between them. For example, Astroturf (fake plastic grass) and real grass will both look green to us, espeically from a satellite image. But living plants absorb radiation from the sun in a part of the light spectrum that we can’t see. There’s a spectral index called the Normalized Difference Vegetation Index (NDVI) which exploits this fact to isolate vegetation in multispectral satellite imagery. So if we look at <a href="https://en.wikipedia.org/wiki/Gillette_Stadium">Gilette Stadium</a> near Boston, we can tell that the three training fields south of the stadium are real grass (they generate high NDVI values, showing up red), while the pitch in the stadium itself is astroturf (generating low NDVI values, showing up blue).</p>
|
||
<div class="quarto-figure quarto-figure-center">
|
||
<figure class="figure">
|
||
<p><img src="images/NDVI.jpg" class="img-fluid figure-img"></p>
|
||
<p></p><figcaption class="figure-caption">VHR image of Gilette Stadium with Sentinel-2 derived NDVI overlay</figcaption><p></p>
|
||
</figure>
|
||
</div>
|
||
<p>In other words, even though these fields are all green and indistinguishable to the human eye, their <em>spectral profiles</em> beyond the visible light spectrum differ, and we can use this information to distinguish between them. Below is a plot of the spectral profiles of different materials, including oil.</p>
|
||
<iframe title="Spectral Profiles of Different Materials" aria-label="Interactive line chart" id="datawrapper-chart-b1kcX" src="https://datawrapper.dwcdn.net/b1kcX/3/" scrolling="no" frameborder="0" style="width: 0; min-width: 100% !important; border: none;" height="400">
|
||
</iframe>
|
||
<script type="text/javascript">!function(){"use strict";window.addEventListener("message",(function(e){if(void 0!==e.data["datawrapper-height"]){var t=document.querySelectorAll("iframe");for(var a in e.data["datawrapper-height"])for(var r=0;r<t.length;r++){if(t[r].contentWindow===e.source)t[r].style.height=e.data["datawrapper-height"][a]+"px"}}}))}();
|
||
</script>
|
||
<p>The European Space Agency’s Sentinel-2 satellite collects spectral information well beyond the visible light spectrum, enabling this sort of analysis. It chops the electromagnetic spectrum up into “bands”, and measures how strongly wavelengths in each of those bands is reflected:</p>
|
||
<p><img src="images/S2_bands.png" class="img-fluid"></p>
|
||
<p>We’ll be using this satellite to distinguish between oil and other materials, similar to the way we were able to distinguish between real and fake grass at Gilette Stadium. First, we’ll have to do a bit of pre-processing on the Sentinel-2 imagery after which we’ll train a machine learning model to identify oil.</p>
|
||
</section>
|
||
<section id="temporal-resolution" class="level3" data-number="3.1.3">
|
||
<h3 data-number="3.1.3" class="anchored" data-anchor-id="temporal-resolution"><span class="header-section-number">3.1.3</span> Temporal Resolution</h3>
|
||
<p>Finally, time There is often a tradeoff between spatial and temporal resolution.</p>
|
||
<p>The Google Maps basemap is very high resolution, available globally, and is freely available. But it has no <em>temporal</em> dimension: it’s a snapshot from one particular point in time. If the thing we’re interested in involves <em>changes</em> over time, this basemap will be of limited use.</p>
|
||
<p>The <strong>“revisit rate”</strong> is the time it takes a satellite to image the same point on earth</p>
|
||
<ul>
|
||
<li><a href="https://sentinel.esa.int/web/sentinel/missions/sentinel-2">Sentinel 2</a>: 5 days</li>
|
||
<li><a href="https://landsat.gsfc.nasa.gov/satellites/landsat-9/#:~:text=Landsat%209%20replaces%20Landsat%207,for%20Landsat%208%20%2B%20Landsat%207.">Landsat 9</a>: 8 days</li>
|
||
<li><a href="https://www.planet.com/pulse/12x-rapid-revisit-announcement/">Planet SkySat</a>: 2-3 hours</li>
|
||
</ul>
|
||
|
||
|
||
</section>
|
||
</section>
|
||
|
||
</main> <!-- /main -->
|
||
<script id="quarto-html-after-body" type="application/javascript">
|
||
window.document.addEventListener("DOMContentLoaded", function (event) {
|
||
const toggleBodyColorMode = (bsSheetEl) => {
|
||
const mode = bsSheetEl.getAttribute("data-mode");
|
||
const bodyEl = window.document.querySelector("body");
|
||
if (mode === "dark") {
|
||
bodyEl.classList.add("quarto-dark");
|
||
bodyEl.classList.remove("quarto-light");
|
||
} else {
|
||
bodyEl.classList.add("quarto-light");
|
||
bodyEl.classList.remove("quarto-dark");
|
||
}
|
||
}
|
||
const toggleBodyColorPrimary = () => {
|
||
const bsSheetEl = window.document.querySelector("link#quarto-bootstrap");
|
||
if (bsSheetEl) {
|
||
toggleBodyColorMode(bsSheetEl);
|
||
}
|
||
}
|
||
toggleBodyColorPrimary();
|
||
const disableStylesheet = (stylesheets) => {
|
||
for (let i=0; i < stylesheets.length; i++) {
|
||
const stylesheet = stylesheets[i];
|
||
stylesheet.rel = 'prefetch';
|
||
}
|
||
}
|
||
const enableStylesheet = (stylesheets) => {
|
||
for (let i=0; i < stylesheets.length; i++) {
|
||
const stylesheet = stylesheets[i];
|
||
stylesheet.rel = 'stylesheet';
|
||
}
|
||
}
|
||
const manageTransitions = (selector, allowTransitions) => {
|
||
const els = window.document.querySelectorAll(selector);
|
||
for (let i=0; i < els.length; i++) {
|
||
const el = els[i];
|
||
if (allowTransitions) {
|
||
el.classList.remove('notransition');
|
||
} else {
|
||
el.classList.add('notransition');
|
||
}
|
||
}
|
||
}
|
||
const toggleColorMode = (alternate) => {
|
||
// Switch the stylesheets
|
||
const alternateStylesheets = window.document.querySelectorAll('link.quarto-color-scheme.quarto-color-alternate');
|
||
manageTransitions('#quarto-margin-sidebar .nav-link', false);
|
||
if (alternate) {
|
||
enableStylesheet(alternateStylesheets);
|
||
for (const sheetNode of alternateStylesheets) {
|
||
if (sheetNode.id === "quarto-bootstrap") {
|
||
toggleBodyColorMode(sheetNode);
|
||
}
|
||
}
|
||
} else {
|
||
disableStylesheet(alternateStylesheets);
|
||
toggleBodyColorPrimary();
|
||
}
|
||
manageTransitions('#quarto-margin-sidebar .nav-link', true);
|
||
// Switch the toggles
|
||
const toggles = window.document.querySelectorAll('.quarto-color-scheme-toggle');
|
||
for (let i=0; i < toggles.length; i++) {
|
||
const toggle = toggles[i];
|
||
if (toggle) {
|
||
if (alternate) {
|
||
toggle.classList.add("alternate");
|
||
} else {
|
||
toggle.classList.remove("alternate");
|
||
}
|
||
}
|
||
}
|
||
// Hack to workaround the fact that safari doesn't
|
||
// properly recolor the scrollbar when toggling (#1455)
|
||
if (navigator.userAgent.indexOf('Safari') > 0 && navigator.userAgent.indexOf('Chrome') == -1) {
|
||
manageTransitions("body", false);
|
||
window.scrollTo(0, 1);
|
||
setTimeout(() => {
|
||
window.scrollTo(0, 0);
|
||
manageTransitions("body", true);
|
||
}, 40);
|
||
}
|
||
}
|
||
const isFileUrl = () => {
|
||
return window.location.protocol === 'file:';
|
||
}
|
||
const hasAlternateSentinel = () => {
|
||
let styleSentinel = getColorSchemeSentinel();
|
||
if (styleSentinel !== null) {
|
||
return styleSentinel === "alternate";
|
||
} else {
|
||
return false;
|
||
}
|
||
}
|
||
const setStyleSentinel = (alternate) => {
|
||
const value = alternate ? "alternate" : "default";
|
||
if (!isFileUrl()) {
|
||
window.localStorage.setItem("quarto-color-scheme", value);
|
||
} else {
|
||
localAlternateSentinel = value;
|
||
}
|
||
}
|
||
const getColorSchemeSentinel = () => {
|
||
if (!isFileUrl()) {
|
||
const storageValue = window.localStorage.getItem("quarto-color-scheme");
|
||
return storageValue != null ? storageValue : localAlternateSentinel;
|
||
} else {
|
||
return localAlternateSentinel;
|
||
}
|
||
}
|
||
let localAlternateSentinel = 'alternate';
|
||
// Dark / light mode switch
|
||
window.quartoToggleColorScheme = () => {
|
||
// Read the current dark / light value
|
||
let toAlternate = !hasAlternateSentinel();
|
||
toggleColorMode(toAlternate);
|
||
setStyleSentinel(toAlternate);
|
||
};
|
||
// Ensure there is a toggle, if there isn't float one in the top right
|
||
if (window.document.querySelector('.quarto-color-scheme-toggle') === null) {
|
||
const a = window.document.createElement('a');
|
||
a.classList.add('top-right');
|
||
a.classList.add('quarto-color-scheme-toggle');
|
||
a.href = "";
|
||
a.onclick = function() { try { window.quartoToggleColorScheme(); } catch {} return false; };
|
||
const i = window.document.createElement("i");
|
||
i.classList.add('bi');
|
||
a.appendChild(i);
|
||
window.document.body.appendChild(a);
|
||
}
|
||
// Switch to dark mode if need be
|
||
if (hasAlternateSentinel()) {
|
||
toggleColorMode(true);
|
||
} else {
|
||
toggleColorMode(false);
|
||
}
|
||
const icon = "";
|
||
const anchorJS = new window.AnchorJS();
|
||
anchorJS.options = {
|
||
placement: 'right',
|
||
icon: icon
|
||
};
|
||
anchorJS.add('.anchored');
|
||
const clipboard = new window.ClipboardJS('.code-copy-button', {
|
||
target: function(trigger) {
|
||
return trigger.previousElementSibling;
|
||
}
|
||
});
|
||
clipboard.on('success', function(e) {
|
||
// button target
|
||
const button = e.trigger;
|
||
// don't keep focus
|
||
button.blur();
|
||
// flash "checked"
|
||
button.classList.add('code-copy-button-checked');
|
||
var currentTitle = button.getAttribute("title");
|
||
button.setAttribute("title", "Copied!");
|
||
let tooltip;
|
||
if (window.bootstrap) {
|
||
button.setAttribute("data-bs-toggle", "tooltip");
|
||
button.setAttribute("data-bs-placement", "left");
|
||
button.setAttribute("data-bs-title", "Copied!");
|
||
tooltip = new bootstrap.Tooltip(button,
|
||
{ trigger: "manual",
|
||
customClass: "code-copy-button-tooltip",
|
||
offset: [0, -8]});
|
||
tooltip.show();
|
||
}
|
||
setTimeout(function() {
|
||
if (tooltip) {
|
||
tooltip.hide();
|
||
button.removeAttribute("data-bs-title");
|
||
button.removeAttribute("data-bs-toggle");
|
||
button.removeAttribute("data-bs-placement");
|
||
}
|
||
button.setAttribute("title", currentTitle);
|
||
button.classList.remove('code-copy-button-checked');
|
||
}, 1000);
|
||
// clear code selection
|
||
e.clearSelection();
|
||
});
|
||
function tippyHover(el, contentFn) {
|
||
const config = {
|
||
allowHTML: true,
|
||
content: contentFn,
|
||
maxWidth: 500,
|
||
delay: 100,
|
||
arrow: false,
|
||
appendTo: function(el) {
|
||
return el.parentElement;
|
||
},
|
||
interactive: true,
|
||
interactiveBorder: 10,
|
||
theme: 'quarto',
|
||
placement: 'bottom-start'
|
||
};
|
||
window.tippy(el, config);
|
||
}
|
||
const noterefs = window.document.querySelectorAll('a[role="doc-noteref"]');
|
||
for (var i=0; i<noterefs.length; i++) {
|
||
const ref = noterefs[i];
|
||
tippyHover(ref, function() {
|
||
// use id or data attribute instead here
|
||
let href = ref.getAttribute('data-footnote-href') || ref.getAttribute('href');
|
||
try { href = new URL(href).hash; } catch {}
|
||
const id = href.replace(/^#\/?/, "");
|
||
const note = window.document.getElementById(id);
|
||
return note.innerHTML;
|
||
});
|
||
}
|
||
const findCites = (el) => {
|
||
const parentEl = el.parentElement;
|
||
if (parentEl) {
|
||
const cites = parentEl.dataset.cites;
|
||
if (cites) {
|
||
return {
|
||
el,
|
||
cites: cites.split(' ')
|
||
};
|
||
} else {
|
||
return findCites(el.parentElement)
|
||
}
|
||
} else {
|
||
return undefined;
|
||
}
|
||
};
|
||
var bibliorefs = window.document.querySelectorAll('a[role="doc-biblioref"]');
|
||
for (var i=0; i<bibliorefs.length; i++) {
|
||
const ref = bibliorefs[i];
|
||
const citeInfo = findCites(ref);
|
||
if (citeInfo) {
|
||
tippyHover(citeInfo.el, function() {
|
||
var popup = window.document.createElement('div');
|
||
citeInfo.cites.forEach(function(cite) {
|
||
var citeDiv = window.document.createElement('div');
|
||
citeDiv.classList.add('hanging-indent');
|
||
citeDiv.classList.add('csl-entry');
|
||
var biblioDiv = window.document.getElementById('ref-' + cite);
|
||
if (biblioDiv) {
|
||
citeDiv.innerHTML = biblioDiv.innerHTML;
|
||
}
|
||
popup.appendChild(citeDiv);
|
||
});
|
||
return popup.innerHTML;
|
||
});
|
||
}
|
||
}
|
||
});
|
||
</script>
|
||
<nav class="page-navigation">
|
||
<div class="nav-page nav-page-previous">
|
||
<a href="./ch2.html" class="pagination-link">
|
||
<i class="bi bi-arrow-left-short"></i> <span class="nav-page-text"><span class="chapter-number">2</span> <span class="chapter-title">Remote Sensing</span></span>
|
||
</a>
|
||
</div>
|
||
<div class="nav-page nav-page-next">
|
||
<a href="./ch4.html" class="pagination-link">
|
||
<span class="nav-page-text"><span class="chapter-number">4</span> <span class="chapter-title">Application Development</span></span> <i class="bi bi-arrow-right-short"></i>
|
||
</a>
|
||
</div>
|
||
</nav>
|
||
</div> <!-- /content -->
|
||
|
||
|
||
|
||
</body></html> |