bellingcat/RS4OSINT
1
0
Fork 0
mirror of https://github.com/bellingcat/RS4OSINT.git synced 2026-06-11 13:08:36 +03:00
Code Issues Packages Projects Releases Wiki Activity

fixed image paths

Browse Source
This commit is contained in:
Ollie Ballinger
2023-04-17 11:46:07 +01:00
parent 7ccf85e48e
commit 9eb020dab7
29 changed files with 1611 additions and 1734 deletions
Download Patch File Download Diff File Expand all files Collapse all files

84
docs/A2_Remote_Sensing.html
View File

@@ -7,7 +7,7 @@
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>Remote Sensing for OSINT - 2&nbsp; Remote Sensing</title>
<title>Remote Sensing for OSINT - Remote Sensing</title>
<style>
code{white-space: pre-wrap;}
span.smallcaps{font-variant: small-caps;}
@@ -167,20 +167,17 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
<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="./index.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">1</span>&nbsp; <span class="chapter-title">Overview</span></span></a>
<a href="./index.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Overview</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./A2_Remote_Sensing.html" class="sidebar-item-text sidebar-link active">
<span class="menu-text"><span class="chapter-number">2</span>&nbsp; <span class="chapter-title">Remote Sensing</span></span></a>
<a href="./A2_Remote_Sensing.html" class="sidebar-item-text sidebar-link active"><span class="chapter-title">Remote Sensing</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./A3_Data_Acquisition.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">3</span>&nbsp; <span class="chapter-title">Data Acquisition</span></span></a>
<a href="./A3_Data_Acquisition.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Data Acquisition</span></a>
</div>
</li>
</ul>
@@ -196,26 +193,22 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
<ul id="quarto-sidebar-section-2" class="collapse list-unstyled sidebar-section depth1 ">
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./B1_Getting_Started.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">4</span>&nbsp; <span class="chapter-title">Getting Started</span></span></a>
<a href="./B1_Getting_Started.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Getting Started</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./B2_Interpreting_Images.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">5</span>&nbsp; <span class="chapter-title">Interpreting Images</span></span></a>
<a href="./B2_Interpreting_Images.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Interpreting Images</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./B3_Image_Series.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">6</span>&nbsp; <span class="chapter-title">Image Series</span></span></a>
<a href="./B3_Image_Series.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Image Series</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./B4_Vectors_Tables.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">7</span>&nbsp; <span class="chapter-title">Vectors and Tables</span></span></a>
<a href="./B4_Vectors_Tables.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Vectors and Tables</span></a>
</div>
</li>
</ul>
@@ -231,32 +224,27 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
<ul id="quarto-sidebar-section-3" class="collapse list-unstyled sidebar-section depth1 ">
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./C1_Lights.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">8</span>&nbsp; <span class="chapter-title">War at Night</span></span></a>
<a href="./C1_Lights.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">War at Night</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./C2_Refineries.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">9</span>&nbsp; <span class="chapter-title">Refinery Identification</span></span></a>
<a href="./C2_Refineries.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Refinery Identification</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./C3_Blast.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">10</span>&nbsp; <span class="chapter-title">Blast Damage Assessment</span></span></a>
<a href="./C3_Blast.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Blast Damage Assessment</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./C4_Ships.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">11</span>&nbsp; <span class="chapter-title">Ship Detection</span></span></a>
<a href="./C4_Ships.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Ship Detection</span></a>
</div>
</li>
<li class="sidebar-item">
<div class="sidebar-item-container">
<a href="./C5_Object_Detection.html" class="sidebar-item-text sidebar-link">
<span class="menu-text"><span class="chapter-number">12</span>&nbsp; <span class="chapter-title">Object Detection</span></span></a>
<a href="./C5_Object_Detection.html" class="sidebar-item-text sidebar-link"><span class="chapter-title">Object Detection</span></a>
</div>
</li>
</ul>
@@ -271,14 +259,14 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
<h2 id="toc-title">Table of contents</h2>
<ul>
<li><a href="#active-and-passive-sensors" id="toc-active-and-passive-sensors" class="nav-link active" data-scroll-target="#active-and-passive-sensors"><span class="header-section-number">2.1</span> Active and Passive Sensors</a></li>
<li><a href="#resolution" id="toc-resolution" class="nav-link" data-scroll-target="#resolution"><span class="header-section-number">2.2</span> Resolution</a>
<li><a href="#active-and-passive-sensors" id="toc-active-and-passive-sensors" class="nav-link active" data-scroll-target="#active-and-passive-sensors">Active and Passive Sensors</a></li>
<li><a href="#resolution" id="toc-resolution" class="nav-link" data-scroll-target="#resolution">Resolution</a>
<ul class="collapse">
<li><a href="#spatial-resolution" id="toc-spatial-resolution" class="nav-link" data-scroll-target="#spatial-resolution"><span class="header-section-number">2.2.1</span> Spatial Resolution</a></li>
<li><a href="#spectral-resolution" id="toc-spectral-resolution" class="nav-link" data-scroll-target="#spectral-resolution"><span class="header-section-number">2.2.2</span> Spectral Resolution</a></li>
<li><a href="#temporal-resolution" id="toc-temporal-resolution" class="nav-link" data-scroll-target="#temporal-resolution"><span class="header-section-number">2.2.3</span> Temporal Resolution</a></li>
<li><a href="#spatial-resolution" id="toc-spatial-resolution" class="nav-link" data-scroll-target="#spatial-resolution">Spatial Resolution</a></li>
<li><a href="#spectral-resolution" id="toc-spectral-resolution" class="nav-link" data-scroll-target="#spectral-resolution">Spectral Resolution</a></li>
<li><a href="#temporal-resolution" id="toc-temporal-resolution" class="nav-link" data-scroll-target="#temporal-resolution">Temporal Resolution</a></li>
</ul></li>
<li><a href="#summary" id="toc-summary" class="nav-link" data-scroll-target="#summary"><span class="header-section-number">2.3</span> Summary</a></li>
<li><a href="#summary" id="toc-summary" class="nav-link" data-scroll-target="#summary">Summary</a></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/RS4OSINT/edit/main/A2_Remote_Sensing.qmd" class="toc-action">Edit this page</a></p></div></div></nav>
</div>
@@ -287,7 +275,7 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
<header id="title-block-header" class="quarto-title-block default">
<div class="quarto-title">
<h1 class="title"><span class="chapter-number">2</span>&nbsp; <span class="chapter-title">Remote Sensing</span></h1>
<h1 class="title"><span class="chapter-title">Remote Sensing</span></h1>
</div>
@@ -303,22 +291,22 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
</header>
<p>Before learning how to load, process, and analyze satellite imagery in Google Earth Engine, it will be helpful to know a few basic principles of remote sensing. This section provides a brief overview of some important concepts and terminology that will be used throughout the course, including active and passive sensors; spatial, spectral and temporal resolution; and orbits.</p>
<section id="active-and-passive-sensors" class="level2" data-number="2.1">
<h2 data-number="2.1" class="anchored" data-anchor-id="active-and-passive-sensors"><span class="header-section-number">2.1</span> Active and Passive Sensors</h2>
<section id="active-and-passive-sensors" class="level2">
<h2 class="anchored" data-anchor-id="active-and-passive-sensors">Active and Passive Sensors</h2>
<p><a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/remote-sensing">Remote sensing</a> is the science of obtaining information about an object or phenomenon without making physical contact with the object. Remote sensing can be done with various types of electromagnetic radiation such as visible, infrared or microwave. The electromagnetic radiation is either emitted or reflected from the object being sensed. The reflected radiation is then collected by a sensor and processed to obtain information about the object.</p>
<p><img src="../images/diagram.png" class="img-fluid"></p>
<p><img src="images/diagram.png" class="img-fluid"></p>
<p>While most satellite imagery is optical, meaning it captures sunlight reflected by the earth’s surface, Synthetic Aperture Radar (SAR) satellites such as Sentinel-1 work by emitting pulses of radio waves and measuring how much of the signal is reflected back. This is similar to the way a bat uses sonar to “see” in the dark: by emitting calls and listening to echoes.</p>
</section>
<section id="resolution" class="level2" data-number="2.2">
<h2 data-number="2.2" class="anchored" data-anchor-id="resolution"><span class="header-section-number">2.2</span> Resolution</h2>
<section id="resolution" class="level2">
<h2 class="anchored" data-anchor-id="resolution">Resolution</h2>
<p>Resolution is one of the most important attributes of satellite imagery. There are three types of resolution: spatial, spectral, and temporal. Let’s look at each of these.</p>
<section id="spatial-resolution" class="level3" data-number="2.2.1">
<h3 data-number="2.2.1" class="anchored" data-anchor-id="spatial-resolution"><span class="header-section-number">2.2.1</span> Spatial Resolution</h3>
<section id="spatial-resolution" class="level3">
<h3 class="anchored" data-anchor-id="spatial-resolution">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/Landsat.png" class="img-fluid"> <img src="images/Sentinel2.png" class="img-fluid"> <img src="images/Maxar.png" class="img-fluid"></p>
</section>
<section id="spectral-resolution" class="level3" data-number="2.2.2">
<h3 data-number="2.2.2" class="anchored" data-anchor-id="spectral-resolution"><span class="header-section-number">2.2.2</span> Spectral Resolution</h3>
<section id="spectral-resolution" class="level3">
<h3 class="anchored" data-anchor-id="spectral-resolution">Spectral Resolution</h3>
<p>What open access imagery lacks in spatial resolution it often makes up for with <em>spectral</em> resolution. Really sharp imagery from MAXAR, for example, mostly collects light in the visible light spectrum, which is what our eyes can see. But there are other parts of the electromagnetic spectrum that we can’t see, but which can be very useful for distinguishing between different materials. Many satellites that have a lower spatial resolution than MAXAR, such as Landsat and Sentinel-2, collect data in a wider range of the electromagnetic spectrum.</p>
<p>Different materials reflect light differently. An apple absorbs shorter wavelengths (e.g.&nbsp;blue and green), and reflects longer wavelengths (red). Our eyes use that information– the color– to distinguish between different objects. Below is a plot of the spectral profiles of different materials:</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">
@@ -337,8 +325,8 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
<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.</p>
<p>Astroturf is a trivial example. But suppose we were interested in identifying makeshift oil refineries in Northern Syria that constitute a key source of rents for whichever group controls them. As demonstrated in the <a href="./C2_Refineries.html">‘Refinery Identification’</a> case study, we can train an algorithm to identify the spectral signatures of oil, and use that to automatically detect them in satellite imagery.</p>
</section>
<section id="temporal-resolution" class="level3" data-number="2.2.3">
<h3 data-number="2.2.3" class="anchored" data-anchor-id="temporal-resolution"><span class="header-section-number">2.2.3</span> Temporal Resolution</h3>
<section id="temporal-resolution" class="level3">
<h3 class="anchored" data-anchor-id="temporal-resolution">Temporal Resolution</h3>
<p>Finally, the frequency with which we can access new imagery is an important consideration. This is called the <strong>temporal resolution</strong>.</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 amount of time it takes for the satellite to pass over the same location twice. For example, the Sentinel-2 constellation’s two satellites can achieve a revisit rate of 5 days, as shown in this cool video from the European Space Agency:</p>
@@ -354,8 +342,8 @@ gtag('config', 'G-RK9ZLZQ6GL', { 'anonymize_ip': true});
</div>
</section>
</section>
<section id="summary" class="level2" data-number="2.3">
<h2 data-number="2.3" class="anchored" data-anchor-id="summary"><span class="header-section-number">2.3</span> Summary</h2>
<section id="summary" class="level2">
<h2 class="anchored" data-anchor-id="summary">Summary</h2>
<p>You should hopefully have a better understanding of what satellite imagery is, and how it can be used to answer questions about the world. In the <a href="A3_Data_acquisition.qmd">next section</a>, we’ll look at the various types of satellite imagery stored in the Google Earth Engine catalog.</p>
@@ -713,12 +701,12 @@ window.document.addEventListener("DOMContentLoaded", function (event) {
<nav class="page-navigation">
<div class="nav-page nav-page-previous">
<a href="./index.html" class="pagination-link">
<i class="bi bi-arrow-left-short"></i> <span class="nav-page-text"><span class="chapter-number">1</span>&nbsp; <span class="chapter-title">Overview</span></span>
<i class="bi bi-arrow-left-short"></i> <span class="nav-page-text"><span class="chapter-title">Overview</span></span>
</a>
</div>
<div class="nav-page nav-page-next">
<a href="./A3_Data_Acquisition.html" class="pagination-link">
<span class="nav-page-text"><span class="chapter-number">3</span>&nbsp; <span class="chapter-title">Data Acquisition</span></span> <i class="bi bi-arrow-right-short"></i>
<span class="nav-page-text"><span class="chapter-title">Data Acquisition</span></span> <i class="bi bi-arrow-right-short"></i>
</a>
</div>
</nav>