Satellite Imagery for Human Rights Monitoring
Satellite images are photographs of the earth captured by satellites orbiting the planet. Satellites that are equipped to take pictures do so by capturing light reflecting back from the earth. When that light data is digitised, it can be processed into an image.
Satellite imagery is a form of remote sensing, the process of collecting data through high-flying aircraft or satellites, and the two terms are often used interchangeably. Remote sensing is one of several geospatial technologies. Others include geographic information systems (GIS), global positioning systems (GPS) and internet mapping technologies.
Non-profit and humanitarian organisations are increasingly using geospatial technologies to conduct disaster damage assessment, create maps to enhance and assist humanitarian response, carry out environmental monitoring, and monitor and evaluate development programmes.
This guide focuses on the use of satellite imagery to monitor and investigate human rights abuses and violations of international humanitarian law.
It is designed for human rights organisations that are starting to think about using satellite imagery in their work.
Satellites have been orbiting earth and collecting images (alongside other data) since the 1950s. However, in the 1990s - when satellite companies began to privatise and the commercial satellite industry began to develop - the technology became more accessible to human rights organisations. Prior to this, most satellites were owned and operated by governments and used sparingly for human rights investigations.
Over the past 20 years, the industry has democratised dramatically. Many new satellites collecting different forms of data, as well as images, are launched every year. This has helped bring the cost of satellite images down, and has led to an increase in low-cost or free online satellite imagery archives. Additionally, open source software packages to process and interpret satellite imagery data have been developed, and are becoming more accessible to everyday users.
Human rights organisations of varying capacities can now utilise satellite imagery in their monitoring and investigation work, in many different ways.
According to the American Association for the Advancement of Science (AAAS) and other satellite imagery experts, most human rights investigations using satellite imagery fall into three broad categories:
Before and after
The most common use for satellite imagery is to investigate events that took place in one location at a specific point in time. Typically, this involves sourcing images of a precise location before and after that point, and then analysing those images to determine changes to the earth. This can help assess damage, locate a specific building or object, or determine if alleged events took place. For example:
Human Rights Watch utilised satellite imagery in an investigation into the destruction of Rohingya villages in Rakhine State in Myanmar, determining that 430 buildings suffered fire related destruction during attacks on the villages.
Amnesty International conducted an investigation into an alleged attack by Boko Haram militants on two villages in North Eastern Nigeria. By sourcing before and after images, Amnesty International was able to determine the destruction of 3,700 structures and corroborate witness testimony.
Physicians for Human Rights, working with the AAAS, used satellite imagery to determine the location of alleged mass graves in Dasht-e-Leili, Afghanistan. AAAS sourced satellite imagery taken between 2000 to 2007 to assess changes to the ground in suspected mass grave locations, ultimately helping identify the excavation of two gravesites.
Amnesty International worked with the AAAS to source and analyse images of the area around Bodo, in the Niger Delta region of Nigeria, and assess the level of damage caused by oil spills. By collecting images of the area over five years, Amnesty International could verify testimonies from local residents and determine that the release of petrochemicals into the area caused substantial damage. The imagery also highlighted limited attempts to clean up the chemicals, even years after the initial release of chemicals.
Human rights organisations are also utilising satellite imagery to determine events that have taken place across a vast area of land, or over longer periods of time. This helps researchers monitor wide-spread phenomenon in an entire region, track trends, or create timelines around when certain events took place. For example:
Amnesty International launched a large scale micro-tasking initiative, Decode Darfur, to collect information on the extent of damage over two years across a vast area of land in Darfur. They worked with online volunteers to review thousands of satellite images and identify key landmarks. Amnesty International then launched a follow-up initiative, Decode the Difference, also using micro-tasking. Volunteers analysed thousands of before and after images covering 326,000 square kilometres of Darfur, to assess where damage had occurred on villages or buildings.
UNOSAT has been conducting ongoing monitoring across Syria since the outbreak of conflict in March 2011. After four years of sourcing and collecting satellite images, UNOSAT produced a report illustrating the large scale impact of the conflict on civilians across the country.
Many human rights organisations are also using satellite imagery to actively monitor ongoing events. Investigators tracking a humanitarian crisis, conflict or other rapidly unfolding situation can now ‘task’ satellites (paying satellite companies to capture an image of a specific location at a specific time in the future or on an ongoing basis). By monitoring events in this way, organisations aim to respond more quickly, or even help to deter human rights abusers. For example:
38 North has been monitoring the use of nuclear weapons by North Korea, and tracks new and continued activity around nuclear test sites by tasking satellites to frequently revisit and image specific locations.
Researchers have frequently used satellites to monitor ongoing conflict situations, and collect data that could provide evidence of violations in international humanitarian law. Active ongoing monitoring of satellite imagery played a crucial role in determining war crimes in Gaza, Georgia, and Sri Lanka.
Some groups, such as the Satellite Sentinel Project used the threat of ongoing satellite imagery monitoring in South Sudan and Sudan in an attempt to prevent conflict and deter human rights abusers.
Tools and Platforms
Platforms for sourcing satellite imagery
|Google Earth||All recognized languages||Free||Google purchases and licences imagery and other satellite data from a number of different providers, although satellite Imagery is primarily provided by Landsat 8. Google Earth also hosts historical imagery data.|
|Google Earth Pro||All recognized languages||Previously $399 USD, now free online||Google Earth Pro uses the same data sources as Google Earth, however, images can be downloaded at a higher resolution.|
|DigitalGlobe Image Finder Tool||English||Free search portal, with access to free and paid-for satellite imagery data||All DigitalGlobe owned and operated satellites: WorldView-1, WorldView-2, WorldView-3, WorldView-4, IKONOS, GeoEye -1, Quickbird|
|Airbus Browse and Order Imagery Tool||English French Spanish Dutch||Free search portal, with access to free and paid-for satellite imagery data||All Airbus owned and operated satellites Pléiades-1A/1B, SPOT 1- 7 TerraSAR-X, DMC Constellation, KazEOSat-1|
|LandInfo||English||Free search portal, with access to free and paid-for satellite imagery data||A search portal combining imagery from a number of high-resolution imagery satellites: GeoEye-1, IKONOS, KOMPSAT 2/3/3A, Pléiades - 1A/1B, Quickbird - 2, Spot 1- 7, TripleSat, WorldView 1/2/3/3s|
|Land Viewer||English||Free search portal, with access to free and paid-for satellite imagery data||Landsat - 7, Landsat - 8, Modis Sentinel - 2|
|EarthImage||English Spanish||Free search portal, with access to free and paid-for satellite imagery data.||Satellite images are licensed from a number of satellite imagery suppliers|
For more information on other free satellite imagery search portals, check out this list produced by GISGeography.
Tools for preparing, processing and interpreting satellite imagery
|Quantum GIS||Most recognized languages||Latest version, 2.18 Las Palmas, released in 2017||Free|
|ArcGIS Pro||Must purchase and install an additional language pack to view interface in a non-English languages. Most recognized languages available for purchase.||Latest version, ArcGis 10.5, released in 2016.||$1500 - $7000 + dependent on licensing agreement and package.|
|eCognition||English||Latest version, Suite 9.2.1, released in 2016.||Prices vary depending on licensing agreement and package, inquiries can be directed here.|
|Planet - a combined imagery search portal and processing software tool||English||Released in 2017||Free|
For more information on other free satellite imagery processing and analysis softwares, check out this list produced by GISGeography.
Access to remote or inaccessible locations
Satellite imagery allows human rights organisations to access and collect data from remote or restricted locations to which they cannot gain access to in person. According to existing international law and treaties, such as the Outer Space Treaty of 1967, satellites are legally allowed to image anywhere on earth, unlike lower-flying aircrafts that must enter a country’s airspace to collect images. How vertically high sovereignty goes is a debated topic and, in many cases, satellites are considered ‘above the law’. There are some caveats to this – satellite imagery providers are still restricted by national legislation or bilateral agreements in their countries of origin – discussed further below.
Ability to ‘travel back in time’
Satellite imagery allows researchers to go back in time and collect evidence from events that have already occurred, by sourcing images from satellite imagery archives. Satellite imagery archives can be accessed for free online, or at a low cost, from certain commercial satellite imagery providers. There are some limits to how far back one can go— the most robust archives provided by DigitalGlobe and Airbus only date back to the late 1990s, and not every inch of the earth was imaged every single day — so searching for an image of a certain location at a precise time can be a challenge. However, if archival images can be sourced, they provide critical baseline data and allow researchers to build timelines of events.
A roadmap for planning
Satellite imagery can provide useful data for human rights researchers before they go into the field, or humanitarian organisations planning to provide humanitarian assistance. The ability to pinpoint a location before conducting field work can save resources and time, and can help evaluate sites of interest to decide if an investigation or mission is worthwhile.
Cover vast areas of land
Satellite images allow organisations to track events that have taken place over a vast area of land, determine patterns, and assess the scale and severity of an event throughout a region. It might be impossible, or require substantial resources and time, to physically travel throughout an area and collect the same information that a single satellite image could provide.
Evidence that can’t be intimidated and provides visual detail
Images provide data that cannot be altered through intimidation in the same way witness testimony. Satellite imagery used as evidence to document events that took place ten years ago will provide the same level of detailed information as they would on the day the events took place. As with any image or data that is interpreted by humans, there is room for misinterpretation or manipulation, discussed further below. However, when satellite images are paired with other strong evidence, they can provide visual evidence to corroborate that alleged events took place and assess the extent of damage.
The cost of a satellite imagery investigation depends greatly on the needs of the organisation. In some cases, satellite imagery can provide a cheap and fast solution (using something as simple as Google Earth). However, organisations that cannot rely solely on archival images will need to budget more to carry out an investigation. Despite recent reductions, costs for tasking new satellite imagery remain high. A researcher needs to know the amount of area they want to image (in square kilometres) before they can work out precise costs.
Higher-quality images that allow analysts to images of the earth in greater detail also cost more. An AAAS handbook lists price ranges for some of the most popular satellite imagery providers, while most satellite imagery providers regularly update price lists on their websites, outlining the cost of accessing archived images or tasking new ones. Several geospatial blogs have compiled rough price lists for different satellite imagery providers.
Responsible data: No causality shown, and cannot be used as stand-alone evidence
Although satellite images are powerful forms of evidence, they should not stand alone as evidence. Images do not always show the causality of an event. Causality is critical to proving that violations of human rights or international humanitarian law have occurred.
Satellite images may depict the level of destruction from an event, or that certain places exist, but other forms of evidence must corroborate and expand upon findings made through satellite imagery, and vice versa. It is critical not to draw conclusions based purely on interpretations of satellite imagery.
Although satellite imagery is becoming increasingly relied on as evidence in trials, there is still some judicial distrust around its use because of the risk of misinterpretation or direct manipulation of an image.
Responsible data: Re-victimisation and security threats
Just as satellite imagery can be used by human rights organisations, it can also be used by the perpetrators of human rights abuses. Human rights organisations should always consider the risks they pose for local populations when collecting and sharing certain satellite imagery data.
Since obtaining informed consent to use satellite images is not always possible, and has yet to become a protection standard, users must ask themselves about the potential negative impact of releasing certain images. For example, releasing geographical coordinates alongside imagery of a protection of civilian (POC) camp in a conflict scenario could give the perpetrators of human rights abuses a roadmap to locating their victims.
Organisations also must consider whether releasing certain images would benefit one party over another in a conflict scenario, and the impact that may have.
National legislation and bilateral agreements
Although international law allows satellites to photograph anywhere on the planet, commercial satellite companies are still restricted by the national legislation in the countries where their primary offices are located. For example, all US satellite companies are restricted by the Kyl-Bingaman Amendment, legislation that prohibits them from selling or publicly sharing high-quality images of Israel. US national security laws also prohibit images of US military operations from being sold or shared. Though each satellite imagery provider should know the legislation they are restricted by, organisations sourcing images must also research national legislation restricting the satellite imagery providers they would like to use.
Processing and interpreting high-quality satellite imagery data needs access to computers and software. It also requires a certain level of technical ability, and access to the internet, to source satellite images, whether they are from archives or newly tasked images.
Although a growing number of satellite imagery software packages are now available, they are not as robust or powerful as the more expensive software used by professional satellite imagery analysts, and require a relatively high level of technical expertise. Additionally, it can be challenging and time-consuming to find the correct image in the databases of different satellite imagery providers, or to reach out to a satellite provider to task new images. Expert satellite analysts believe that technical capacity is the biggest barrier preventing human rights groups from using satellite images more widely.
Interpreting satellite imagery effectively is also a highly technical skill. Being directly involved in ground research or an investigation can also an analyst’s perception of what they see in an image. For example, a black car in a field might be misinterpreted as a pile of black body bags if that is what the investigator is looking for. It takes training, experience and a sharp eye to carry out complicated imagery analysis accurately.
Reliance on external expertise for imagery analysis
Given the challenges of sourcing, processing and interpreting satellite imagery in-house, human rights groups often rely on outside expertise to support their satellite imagery research. To this day, organisations like the Office of the United Nations High Commissioner for Human Rights (OHCHR) are outsourcing their analysis to United Nations Operational Satellite Applications Programme (UNOSAT). Relying on third-party satellite imagery experts creates two challenges:
Confidentiality when relying on a third party. Information must be provided to a satellite analyst for them to carry out an effective analysis, or even source images of the correct location. Researchers must be willing to provide enough information to help an analyst without jeopardising their work’s confidentiality. Trusting a third party – particularly a third party that may have competing client interests – can be a challenge. For example, DigitalGlobe (arguably the world’s leading provider of satellite imagery, who also provide expert imagery analysis services) also provide imagery and analysis for oil companies, the US Department of Defense, and other paying clients. Competing client interests and a commercial company’s bottom line could jeopardise the confidentiality of an investigation.
Lack of internal peer review and cross-referencing: People make mistakes and have inherent biases, and misinterpretations of satellite images are possible. Organisations needing to outsource imagery analysis are likely to also lack the capacity to conduct a thorough peer review or cross-reference the imagery analysis reports they receive from third-party analysts.
Some expert analysts have shared their concerns over the lack of peer review in the sector, and the level of trust organisations place in third-party analysts. Some third-party imagery analysts, such as UNOSAT and the AAAS, do conduct internal peer reviews before sharing any satellite imagery reports with clients. When negotiating a contract with external analysts, Human rights organisations should request the imagery analysis reports they commission go through a peer review process before being completed and shared with them, and that the details of the peer review process are also shared.
This section is designed to help those new to using satellite imagery for human rights fact-finding get started.
The first steps in planning are to: determine if satellite images are really needed, decide what types of images are needed, decide if external satellite imagery analysis expertise is necessary, and, if so, find an analyst to work with.
Determine if an investigation is possible or needed
Satellite imagery investigations take time and resources, and do not always produce results. Many human rights investigations also do not actually require satellite imagery. It’s important to determine if remote sensing is possible or if it is worth it for an organisation. The AAAS suggests asking the following questions before deciding to move forward: * Did the event in question involve significant changes to buildings, roads, vegetation cover, vehicles or other features larger than 2-3 square metres? * Is the precise location of the event in question known, or can it be determined? * Is the date of the event known, or can it be determined? * Did the event occur after 1999, when the first commercial high-resolution satellite was launched?
Researchers should be able to answer yes to all of these questions before moving forward with an investigation.
Determine what type of images are needed
The next step is to think about the type of images needed. This will help when working with an analyst or sourcing the images independently.
New images, old images, or both?
First, a researcher needs to determine if their investigation requires tasking a satellite to collect a new image, or if they can rely on existing satellite imagery archives. If the event they are tracking took place in the past, they may be able to rely on archived images. If they are conducting ongoing monitoring or require a very recent photo to compare to an older one, it is likely they will need to task a satellite.
Researchers should determine their ideal dates (months and years) for when they hope the images were captured. However, they should also prepare to make some compromises; satellites have not captured every inch of the earth every day since 1999.
Imaging satellites have varied capabilities and capture different kinds of image data at different times, affecting the type of image that can be produced. Satellites collect four types of resolution: Spatial, Temporal, Spectral, and Radiometric.
Spatial resolution refers to how close to the earth a satellite can image. Generally, there are three categories of spatial resolution: low resolution images (anything larger than 30 metres is visible), medium resolution (anything from 2-30 metres is visible) and high resolution (objects under two metres in size are visible).
Temporal resolution refers to when data is collected by satellites, ultimately impacting how often and when a satellite can capture certain locations.
Spectral resolution refers to a satellite’s ability to take in certain wavelengths of light, ultimately impacting how the processed photo will be coloured.
Radiometric resolution refers to the ability of a satellite to take in different levels of energy, ultimately impacting image depth, contrast and brightness.
A general rule of thumb is that larger, more established satellite imagery providers tend to have higher-quality cameras offering better spatial resolution. However, smaller, newer satellite imagery providers offer better temporal resolution (meaning a faster revisit time), but lower-quality images and less archived material because they have not been collecting imagery for as long.
Does an investigation require external expertise?
Once an organisation knows the type of images needed, and the level of complexity of their investigation, they can determine if they need external technical expertise to collect and interpret the images.
Some basic satellite imagery investigations may only require a tool like Google Earth to help locate a specific place or source a single image, in which case external expertise in satellite imagery analysis may not be necessary. Additionally, some basic before and after imagery comparisons, using archived images, may not require professional interpretation.
However, if tasking a satellite is necessary, or if the evidence will be used publicly in advocacy or trials, it is recommended to work with a trained satellite imagery analyst. Relying on image interpretation experts will help build credibility for investigations and ensure objectivity. Human rights investigators will often work with forensics experts to assist in investigations. Working with a trained satellite imagery analyst should be looked at in the same way: it takes training and a technical understanding of how to process and interpret imagery to conduct a robust and credible investigation.
Finding a satellite imagery analyst to work with
There are several places to seek professional assistance. The AAAS and UNOSAT provide low cost (and sometimes free) services to non-profit organisations seeking support in satellite imagery sourcing and interpretation, and most commercial satellite imagery providers also offer analysis services. Some licensed imagery re-sellers, as well as private analysis firms such as AllSource Analysis or Satellite Imaging Corp, also provide sourcing, processing and interpretation support.
When selecting an analyst to work with, organisations should reach out to several providers to discuss: 1) their experience working on human rights investigations, 2) their fees and timelines, 3) their other clients and confidentiality agreements between clients, 4) their process for peer review, and 5) licensing rights to the images and how their independent analysis can be referenced in a human rights report or advocacy.
Ultimately, organisations should seek to find an analyst who can help source the correct images, process and interpret the images and then produce a final report of their findings that can be referenced in an independent human rights report and made public.
Determining the search location
Whether working with a satellite analyst or conducting an independent investigation, the first step of a satellite imagery investigation is to determine a search location. If an organisation is unable to identify exact coordinates for the event in question, tools like Google Earth can help identify a more narrow search area.
Researchers can start by looking for man-made landmarks (cities, villages, cell phone towers) or natural features (rivers, mountains) that can help narrow in on a search area. The smaller a search area, the better for sourcing imagery.
Sourcing satellite imagery
After narrowing down the search area, or finding precise coordinates, and understanding the types of images needed (as determined in the planning process) researchers can begin looking at what different satellite providers have on offer. The AAAS and VentureRadar have developed lists of commercial satellite imagery providers. An easy place to start searching is with the DigitalGlobe Image Finder Tool or the Airbus Browse and Order Imagery Tool. Both offer user-friendly online imagery archives. Other commercial satellite imagery providers also offer similar searching capabilities on their websites.
Once researchers have located the images through an online archive, they can email the satellite company or image reseller directly (most image finding tools include information on where to send imagery requests) to request the image file. The provider typically takes a few hours to a few days to respond, process the request, and send back the image file.
Files are usually sent back via FTP, essentially a link from which the requester can download the image file. The AAAS handbook on image ordering and analysis provides detailed step-by-step instructions on this process. If requesting images to be tasked, researchers should reach out to the email address provided on the satellite company website to start a conversation. Depending on the company’s other clients and demand for time on certain satellites, it could take a few hours to weeks to task a satellite to collect new images. Although it is more costly to task satellites than to retrieve photos through an archive, some providers offer a non-profit discount.
Processing and preparation of satellite images
There is now a variety of open source satellite imagery processing software packages. Each software allows users to adapt and extract data from satellite images in slightly different ways, but all of them include guides on how to properly use the software, such as this training manual provided by the free online software Quantum GIS (a popular choice and highly rated program). Paid-for softwares like ArcGIS Pro can be expensive, but provide more features and are often the tools of choice for professional analysts.
Although processing is quite complex, an analyst typically follows these steps: they download the software, upload the imagery files retrieved from the satellite imagery provider, ensure the files and images are prepared for analysis and then conduct an assessment. If comparing images from different satellite companies or archives, they will likely be in different colours and come in different sizes.
To properly prepare images for an interpretation, it is important to align and georeference them before moving forward (for example, a tree in one image should line up with the same tree in the other image).
Interpreting satellite images
Although satellite imagery interpretation is a skill that can take years to hone, beginners can adopt some basic analysis techniques to conduct their own interpretation for easier investigations (like comparing before and after images of a single location, or determining the location of a building). This guide outlines five key tips and strategies for satellite imagery interpretation. It is important that analysts do not draw conclusions based on imagery—even leading satellite analysts do not do so. What an untrained analyst might determine as mass graves, a well-trained analyst would quickly identify as a cloud’s shadow.
More training programmes are also becoming available in satellite imagery analysis, to help unqualified researchers learn the basics of satellite imagery interpretation.
Working with an analyst to source, process and interpret satellite images
Before and during the investigation
Prior to launching an investigation, an analyst needs coordinates for the location under investigation, or, at minimum, a rough idea of the location. Tools like Google Earth can help identify a location and narrow the search area. The AAAS has written a detailed manual on how to procure and order satellite images, which includes guidelines on how to identify locations using Google Earth. If exact coordinates are not possible, a KML file of the search area exported from Google Earth can be provided to the analyst.
To support analysts, researchers should plan out what data they can provide in advance. The more information that can be provided to an analyst throughout an investigation, the better.
Cultural practices in the location being searched can also be relevant, such as if people in the region are nomadic or live in certain kinds of structures. This kind of information can help an analyst who has never been to a region better understand what normal patterns look like. This information also does not need to jeopardize confidentiality.
After the investigation
In most cases an analyst will provide a final report with their findings, including images marked with areas of interest. Researchers can then reference the report in their research work, or publish components of it alongside their own research findings, depending on the agreement made with the analyst.
When groups like the AAAS produce third party satellite imagery analysis reports for trials or non-profits, they also produce reports outlining each step they took during the imagery processing stage, detailing exactly which manipulations or tools were applied to the image (such as zooming, sharpening, adding filters etc). This provides a clear chain of custody and evidence that images were not altered in a way that changed the nature of the content. Groups seeking a third party analyst should request similar reports alongside the imagery analysis report to better understand the various changes made to an image during the interpretation process.
Before releasing satellite images or coordinates alongside satellite images, it’s important to consider if the information could be dangerous or cause harm to any individuals. Special consideration of the ‘do no harm’ principle should be applied as it would be with other images or evidence being released to the public.
Satellite imagery should always be paired with other evidence in order to claim or prove violations of human rights or international humanitarian law, they cannot stand alone as evidence.
This site was created to introduce human rights researchers to the ins and outs of using satellite imagery to monitor and investigate human rights abuses and violations of international humanitarian law.
It was written and researched by Robin Pierro.
It is based on Robin’s MA thesis at the European Inter-University Centre for Human Rights and Democratisation on the opportunities and implications of using new ICT tools for human rights fact-finding, which included a survey with 66 human rights researchers and over 30 interviews with technology and fact-finding experts.
This version of the guide was commissioned and edited by Tom Walker from The Engine Room, an international organisation that helps activists, organisations and social change agents to use data and technology to increase their impact.
Robin Pierro works at the intersection of human rights, technology and journalism. She was previously Senior Programme Manager with Journalists for Human Rights (JHR), overseeing programmes across sub-Saharan Africa and in remote Indigenous communities throughout Canada. This work helped build the capacity of local journalists and activists to highlight pressing human rights issues, and created a more enabling environment for documenting and reporting on rights issues. Robin now works with the Fund for Global Human Rights, mobilising resources and technical assistance to support local human rights organisations bring power to account.
Tom Walker is Research Lead at The Engine Room.
Icon by Ben Davis, Creative Commons.