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Updated translations from Phrase
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92 changes: 92 additions & 0 deletions markdown-docs/datasets/disp_faq.en.md
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# Displacement Products FAQs

**What datasets can be visualized in the Displacement Portal?**

The Displacement Portal displays the cumulative displacement and velocity (i.e., averaged displacement over time) on a map.
This information was derived from the “short_wavelength_displacement” layer found within each OPERA DISP dataset.

**What is “short-wavelength (i.e., local) displacement”?**

The short-wavelength displacement represents ground movement measured in the satellite line-of-sight (LOS) with long-wavelength signals filtered, so it is a basic, uncalibrated displacement measurement.
The product filters wavelengths >30 km . This means that large-scale signals, such as atmospheric effects, large-scale subsidence, and plate motion, are filtered in order to highlight local surface displacement.
In some cases, the local displacement may have opposite LOS motion to the actual displacement due to filter effects (see the section “**How do I interpret displacement in the Portal**”).
The “short_wavelength_displacement” layer comes with the DISP product package and is made for visualization purposes.
This filtering approach also removes the need to select a local reference point (common for basic, uncalibrated InSAR displacements).
The velocity maps and displacement time series displayed in the Displacement Portal are derived from this layer.

For the displacement measurement that includes both short- and long-wavelength signals, users are directed to look at the “unfiltered” displacement layer within the DISP product.

In the future, the portal will host Ortho velocity maps derived from the upcoming OPERA Vertical Land Motion (VLM) product suite.
Unlike the current Basic velocity maps which are computed in the satellite line-of-sight, the Ortho velocity maps will be computed for the vertical and east-west directions.

**How do I interpret displacement in the Portal?**

The filtering approach used to generate the “short-wavelength” layers is intended to highlight local displacement by removing long-wavelength signals.
Large spatial features that exceed the filter kernel size of 30 km, such as subsidence in Central Valley, California and in Mexico City, are filtered to emphasize local displacement signals.
These locations will look different than the unfiltered time-series in the product displacement layer.

Below we show synthetic examples of filtered and unfiltered displacement signals.
The examples show that residual displacement patterns can emerge after filtering (see figure below).

More details can be found in this [notebook](https://dolphin-insar--561.org.readthedocs.build/en/561/notebooks/demo-filtering-sizes/).

![Screenshot](/images/disp_faq_1.png){: style="height:900px;width:700px"}

The figure above shows an example of the filtering approach (>30 km filter kernel) applied to a 65 km diameter subsidence bowl (left) and creeping right lateral transform fault (right).
After the long-wavelength signal is filtered only the local displacement remains. The filtered subsidence bowl has apparent uplift along the edges.
An analogous real-world example can be found in the Displacement Portal along the Central Valley in California.
The filtered fault shows local displacement next to the fault and no displacement in the far field.
An analogous real-world example can be found in the Displacement Portal along the Central San Andreas Fault near Parkfield, CA.

**What if I want to access the unfiltered displacement data?**

The unfiltered displacement datasets are available and can be downloaded as part of the OPERA-S1 dataset through [Vertex](https://search.asf.alaska.edu).
Choose the DISP-S1 file type, and you will see the downloadable NetCDF file (with a “.nc” extension) available.
You must be signed into your Earthdata account to download these products.
Refer to the [Vertex User Guide](/vertex/manual/#vertex-getting-started-user-guide) for more information.

Note that the unfiltered displacement layer from the DISP product will not reflect what is visualized in the portal, since the portal only displays the short-wavelength layer.

**What are the data units in the Displacement Portal?**

Velocities plotted in map-view are in units of meters per year (m/yr) in the line-of-sight direction.
The map overlay is colorized from -0.03 m/yr (blue) to +0.03 m/yr (red).
Local displacement in the time series plot is in units of meters in the line-of-sight direction.

**How are the time series referenced in time and space?**

Each Displacement Product measures ground displacement relative to a specific reference date, which can change over time.
The portal displays cumulative velocity and displacement from the first available date.
Note, due to the short-wavelength filtering process, there is no local spatial reference point needed.

**How often are the data updated in the portal?**

New data is continuously being added to the archive and is immediately available for time series analysis.
The OPERA velocity measurements displayed in the portal are updated weekly.

**Why are some points missing?**

In map-view: Points are masked if any of the datasets fail to meet a set of quality metrics, such as level of temporal coherence and phase similarity amongst neighboring pixels.
These quality metrics are captured in the Recommended Mask layer that can be downloaded with the Displacement product.
Factors that may contribute to these quality metric issues may also include the presence of water bodies, ground motions that are too rapid to be resolved, and changes in surface characteristics (e.g. vegetation loss/growth and/or snow/ice cover).

In the time series plot: Masked pixels are not plotted.

**Why do I get an error message (e.g. “Timeseries Service Error”) when trying to plot data?**

These are the types of errors that will cause the "Timeseries Service Error" message:

- The selected area is outside the dataset coverage (e.g. over the ocean, over Europe, etc.)
- There is no data processed over the given frame yet. You can check the [rollout map layer](/vertex/displacement/#rollout) for more details.
- There is no valid data at the selected point. This happens when all short-wavelength displacement samples for the given AOI are pre-filtered by the dataset's validity mask.

**Are InSAR corrections applied to the time-series displayed in the portal?**

No. But InSAR corrections such as solid earth tides (SET) and ionospheric delay are added as separate layers in the DISP product and can be made outside of the portal.
DEM errors can be corrected using the provided “perpendicular_baseline” layer.
Tropospheric corrections will be available in the upcoming OPERA Level-4 Troposphere Zenith Radar Delays (TROPO) product.
Refer to the DISP product specification document for additional details and this jupyter notebook on how to apply these corrections.

**Where is the product specification document?**

The dedicated DISP-S1 product page can be found [here](https://www.jpl.nasa.gov/go/opera/products/disp-product-suite/).
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# Preguntas Frecuentes sobre los Productos de Desplazamiento

**¿Qué conjuntos de datos pueden visualizarse en el Portal de Desplazamiento?**

El Portal de Desplazamiento muestra el desplazamiento acumulado y la velocidad (es decir, el desplazamiento promedio en el tiempo) en un mapa.
Esta información fue derivada de la capa “short_wavelength_displacement” que se encuentra dentro de cada conjunto de datos DISP-S1.

**¿Qué es el “short-wavelength displacement”?**

El desplazamiento de longitud de onda corta representa el movimiento del suelo de la superficie terrestre observado en la línea de visión (LOS) del satélite, con las señales de longitud de onda larga eliminadas (es decir, >25 km).
Esto significa que señales de gran escala, como los efectos atmosféricos, se filtran con el fin de resaltar los desplazamientos de superficie a pequeña escala.
Estos datos se proporcionan como la capa “short_wavelength_displacement” dentro del paquete de productos DISP-S1.
Los mapas de velocidad y deformación acumulada que se muestran aquí son derivados de esta capa.

Para la medición de desplazamiento que incluye señales tanto de longitud de onda corta como larga, se recomienda a los usuarios consultar la capa sin filtrar “displacement” dentro del producto DISP-S1.
Esto puede hacer que ciertas características espaciales extensas, como el Valle Central o la Ciudad de México, se vean diferentes en el portal.
El propósito del portal es resaltar la deformación local, y todas las señales pueden recuperarse a partir de la serie temporal sin filtrar.
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# Displacement Products Usage

##Displacement Product Considerations and Limitations
This provides some usage notes for the OPERA Displacement products.
Access the [Displacement Portal](https://displacement.asf.alaska.edu/) to interact with these products, or see the [Displacement Portal documentation](/vertex/displacement) for more details on using the Portal.

***Caution on interpreting the data!***

## Should data indicating ground movement on a house be a cause for concern?

InSAR can detect small ground movements with millimeter-scale precision, but not all points indicate structural issues or land displacement.
Many structures and surfaces move naturally due to environmental factors, affecting how radar signals are reflected.
As an example, bridges expand and contract with temperature changes, which may be detected by InSAR but are not necessarily signs of structural damage.
Since such movements are expected and accounted for in engineering and construction, InSAR data should always be analyzed alongside additional information and expert knowledge to distinguish natural behavior from potential issues affecting specific structures and infrastructure.

## Isolated Measurements and Outliers
InSAR ground motion measurements are based on reflected radar signals, which can originate from both the Earth's surface and human-made structures.
Signal reflecting from structures may be misinterpreted. For example, thermal expansion in buildings can appear as displacement, even though it does not indicate actual ground motion.
Similarly, harvest cycles in crop fields can cause sudden changes in reflectivity, affecting displacement measurements.

The Displacement Portal uses the Recommended Mask in the OPERA DISP products to reduce outliers. Pixels near masked areas might have lower quality.
For more dependable analysis, prioritize groups of points showing similar movement over single points with unusual motion.

## What is the size of each pixel and how is displacement measured within that pixel?
Each pixel in the Basic Velocity map represents a 30m x 30m area.
While you can select a point in the portal, the displayed displacement data is the average for that entire pixel.
Therefore, recorded movements are an aggregate of all surface changes within the 30m x 30m area, not a precise point measurement.
Additionally, the mosaic map pixels do not directly correspond to the underlying data pixels.
Clicking in different corners of a single mosaic pixel can yield different time series from distinct underlying data pixels.
The Basic Velocity mosaic serves to indicate trends and is not intended for rigorous analysis.

## Contact
For any questions regarding the Displacement Portal, please contact ASF at uso@asf.alaska.edu.

For any questions or inquiries regarding the Displacement Products, please contact opera.sep@jpl.nasa.gov.
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# Uso de productos de desplazamiento

## ¿Qué son los productos de desplazamiento?
Los productos de desplazamiento de superficie (DISP) de OPERA son datos de desplazamiento derivados del radar de apertura sintética interferométrica (InSAR) con ruido de descorrelación reducido utilizando un enfoque híbrido de procesamiento de series temporales de dispersor persistente (PS) y dispersor distribuido (DS). Todos los productos de desplazamiento se proporcionan en la dirección de la línea de visión (LOS) del satélite, lo que significa que los movimientos de la superficie se miden en relación con el satélite, lo que indica si un punto se está acercando (valor positivo) o alejándose (valor negativo) del satélite. Estos productos proporcionan información sobre los movimientos antropogénicos y naturales de la superficie de la Tierra, como el hundimiento, la tectónica y los deslizamientos de tierra. Los productos cubrirán América del Norte y serán procesados a partir de 2016 para la misión Sentinel-1. Se generarán nuevos productos a medida que los datos de Sentinel-1 estén disponibles.

El Portal de Desplazamiento ofrece la posibilidad de visualizar e interactuar con estos productos.
[añadir más tarde]: <> (Acceda al [Portal de Desplazamiento](https://displacement.asf.alaska.edu/) para empezar. Tenga en cuenta que el Portal de desplazamiento también está disponible yendo a [Vértice](https://search.asf.alaska.edu) y seleccionando Desplazamiento en el menú desplegable Tipo de búsqueda).

Esto proporciona algunas notas de uso para estos productos.

## Precaución con la interpretación de datos
¿Deberían ser motivo de preocupación los datos que indican el movimiento del suelo en una casa?

InSAR detecta pequeños movimientos del terreno con precisión a escala milimétrica, pero no todos los puntos indican problemas estructurales o deformación del terreno.
Muchas estructuras y superficies se mueven naturalmente debido a factores ambientales, lo que afecta la forma en que se reflejan las señales de radar.
Por ejemplo, los puentes se expanden y contraen con los cambios de temperatura, que pueden ser detectados por InSAR, pero no son necesariamente signos de falla estructural.
Dado que tales movimientos se esperan y se tienen en cuenta en la ingeniería y la construcción, los datos InSAR siempre deben analizarse junto con información adicional y conocimiento experto para distinguir el comportamiento natural de los problemas potenciales, especialmente para ubicaciones específicas como las casas.

## Mediciones aisladas y valores atípicos
Las mediciones de movimiento terrestre InSAR se basan en señales de radar reflejadas, que pueden provenir tanto de la superficie de la Tierra como de estructuras hechas por el hombre.
La señal que se refleja en estas estructuras puede ser malinterpretada. Por ejemplo, la expansión térmica en los edificios puede aparecer como desplazamiento, aunque no indique el movimiento real del suelo.
Del mismo modo, los ciclos de cosecha en los campos de cultivo pueden causar cambios bruscos en la reflectividad, lo que afecta a las mediciones de desplazamiento.

Los productos DISP-S1 mitigan los valores atípicos mediante umbrales de enmascaramiento que priorizan la estabilidad del punto de medición a lo largo del tiempo.
Sin embargo, los píxeles cercanos a las regiones enmascaradas pueden tener una calidad límite.
Para un análisis más fiable, concéntrese en grupos de puntos con patrones de movimiento coherentes en lugar de puntos aislados con movimientos inesperados.

## Área de interés frente a la posición del píxel
Cada píxel que se muestra en la vista del mapa representa un área de 30 m de ancho y la altura varía según la latitud.
El portal proporciona una ubicación de punto al dibujar un punto de forma interactiva, pero es importante recordar que los datos de desplazamiento corresponden a la totalidad de los 30 m x 30 m en los que se encuentra el punto.
Los movimientos registrados representan un agregado de todos los cambios de superficie dentro de esa área de píxeles en lugar de una medición precisa de un solo punto.
También tenga en cuenta que los píxeles del mosaico no se corresponden 1 a 1 con los píxeles de datos subyacentes, por lo que es posible hacer clic en dos esquinas opuestas de un píxel de mosaico y obtener dos series temporales diferentes a partir de dos píxeles de datos subyacentes diferentes.
El mosaico se proporciona para resaltar tendencias y no pretende ser una fuente de datos rigurosa para el análisis.

## Contacto
Si tiene alguna pregunta sobre el Portal de Desplazamiento, comuníquese con ASF en uso@asf.alaska.edu.

Para cualquier pregunta o consulta relacionada con los Productos de Desplazamiento, póngase en contacto con opera.sep@jpl.nasa.gov.
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