SAR Imaging - Revision history

Uwasa: /* Frequency bands and some of their usage */

2022-02-09T09:01:02Z

Frequency bands and some of their usage

← Older revision		Revision as of 12:01, 9 February 2022
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	* VV: the signal is send as vertically polarized and received as vertically polarized. This leads strong reflection from		* VV: the signal is send as vertically polarized and received as vertically polarized. This leads strong reflection from
	* HH: The signal is send as horizontally polarized and received as horizontally polarized. This leads strong reception from smooth specular surfaces.		* HH: The signal is send as horizontally polarized and received as horizontally polarized. This leads strong reception from smooth specular surfaces.
	* VH: The signal is send as vertically polarized by the receiver only collects horizontally polarized signals. This combination mostly blocks the		* VH: The signal is send as vertically polarized by the receiver only collects horizontally polarized signals. This cross-polarization combination mostly blocks the pure specular reflections which is keeping the polarization angle. On the contrary, the reflections from more complex surfaces having multiple scattering looses the polarization angle and is therefore partly received.
			*HV: Similar cross polarization method than VH.

	More in depth discussion of [https://sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar/product-overview/polarimetry polarimetric SAR].		More in depth discussion of [https://sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar/product-overview/polarimetry polarimetric SAR].
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	* 12 days repeat cycle (each)		* 12 days repeat cycle (each)
	* The C-SAR’s advantage appears to be an ability to operate at C-band wavelength that cannot be blocked by cloud cover or insufficient light.		* The C-SAR’s advantage appears to be an ability to operate at C-band wavelength that cannot be blocked by cloud cover or insufficient light.
	* 5.405 GHz, bandwidth 0-100 MHz, polarization HH+HV, ~~VVV~~+VH, VV, HH		* 5.405 GHz, bandwidth 0-100 MHz, polarization HH+HV, VV+VH, VV, HH
	* Azimuth beam width 0.23”		* Azimuth beam width 0.23”
	* Available data products with different level of preprocessing		* Available data products with different level of preprocessing

Uwasa: /* Frequency bands and some of their usage */

2022-02-09T08:33:17Z

Frequency bands and some of their usage

← Older revision		Revision as of 11:33, 9 February 2022
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	The backscatter behavior of C-band is less predictable. Due to volume scattering effects, the layer of backscattering is less determined and does not correspond directly to a terrain surface — neither the vegetation surface nor the ground surface.		The backscatter behavior of C-band is less predictable. Due to volume scattering effects, the layer of backscattering is less determined and does not correspond directly to a terrain surface — neither the vegetation surface nor the ground surface.

			The SAR satellites usually send the radio signal either vertically (V) or horizontally (H) polarized. They can also receive the reflected signal back using either vertical or horizontal polarizer. The polarization angles used in transmission and reception can therefore form the following four combinations:

			* VV: the signal is send as vertically polarized and received as vertically polarized. This leads strong reflection from
			* HH: The signal is send as horizontally polarized and received as horizontally polarized. This leads strong reception from smooth specular surfaces.
			* VH: The signal is send as vertically polarized by the receiver only collects horizontally polarized signals. This combination mostly blocks the

			More in depth discussion of [https://sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar/product-overview/polarimetry polarimetric SAR].

	==== Sentinel 1 ====		==== Sentinel 1 ====

Uwasa: Added more links

2022-02-09T08:26:06Z

Added more links

← Older revision		Revision as of 11:26, 9 February 2022
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	** ground range Detected geo-referenced products (GRD): All data is projected to ground range using an Earth ellipsoid model corrected with specified terrain heigh		** ground range Detected geo-referenced products (GRD): All data is projected to ground range using an Earth ellipsoid model corrected with specified terrain heigh
	* Level-2 Products: geo-located geophysical products copied from Level-1. Level-2 Ocean (OCN) products applicable for wind, wave and currents can have geophysical components obtained from the SAR data like: Ocean Wind field (OWI), Ocean Swell spectral range (OSW), Surface Radial Velocity (RVL), Availability of each one highly depends on mode of acquisition		* Level-2 Products: geo-located geophysical products copied from Level-1. Level-2 Ocean (OCN) products applicable for wind, wave and currents can have geophysical components obtained from the SAR data like: Ocean Wind field (OWI), Ocean Swell spectral range (OSW), Surface Radial Velocity (RVL), Availability of each one highly depends on mode of acquisition

			=== Tutorials and learning resources ===

			* [http://step.esa.int/main/doc/tutorials/ ESA tutorials]
			* [https://asf.alaska.edu/information/sar-information/what-is-sar/ What is SAR?], material from the University of Alaska
			* Tutorial for [https://www.youtube.com/watch?v=CBIlTOl2po4&t=1760s downloading data from SentinelHUB]
			* How to get free research access to Copernicus using [https://www.sentinel-hub.com/Network-of-Resources/ Network of Resources (NOR)]
			* Custom [https://custom-scripts.sentinel-hub.com/sentinel-1/sar-ice/ scripts for ice evaluation using] S1 SAR data

			=== Google tools for accessing and processing EO data ===

			* [https://developers.google.com/earth-engine Google Earth Engine] online notebooks and Python and JavasScript APIs

			=== ESA tools for accessing and processing EO data (These are installed in the RUS environment) ===

			* Access Sentinel Hub from [https://medium.com/sentinel-hub/control-sentinel-hub-from-within-qgis-2a83eb7f13db QGIS], also [https://docs.csc.fi/apps/qgis/ available in Puhti in CSC] for those who have access to CSC services.
			* [https://github.com/sentinel-hub/example-notebooks/blob/master/Slippy%20maps%20in%20Jupyter.ipynb Python Sentinel API in Jupyter notebook] (example)
			* Python Sentinel [https://sentinelhub-py.readthedocs.io/en/latest/examples/process_request.html API for downloading Sentinel data] by Sentinel HUB
			* [https://www.sentinel-hub.com/develop/integrate/python-integrate/ Python and JavaScript Sentinel API:s]
			* [http://step.esa.int/main/toolboxes/snap/ SNAP], also available in [https://docs.csc.fi/apps/snap/ Puhti in CSC] for those who have access to CSC services
			* BRAT ([http://www.altimetry.info/ Basic Radar Altimetry Toolbox])
			* Libraries:
			** [https://gdal.org/ GDAL] (raster and vector geospatial data library), [https://docs.csc.fi/apps/gdal/ also available in Puhti in CSC] for those who have access to CSC services
			** [https://www.orfeo-toolbox.org/ Orfeo Toolbox (OTB)] (Open Source processing of remote sensing images) [https://docs.csc.fi/apps/otb/ also available in CSC]
			** [http://step.esa.int/main/snap-supported-plugins/sen2cor/ Sen2Cor], SNAP plugin, processor for Sentinel-2 Level 2A product generation and formatting, [https://docs.csc.fi/apps/sen2cor/ also available in Puhti in CSC] for those who have access to CSC services
			** [http://step.esa.int/main/snap-supported-plugins/snaphu/ SNAPHU], SNAP plugin, two-dimensional phase unwrapping to recover unambiguous phase data from a 2-D array of phase values known only modulo 2pi rad.

			RUS environment can be used as a virtual server in ESA:s server room or as a Docker image. Both are Linux environments, with all above tools and many others already installed. RUS is only available for EU citizens. The tools can be also installed in normal Linux computer, and then there is no need for Docker or other virtualization platform, and the resources of the computer can therefore used more efficiently.

Uwasa: Added sentinel 1 information

2022-02-09T08:07:52Z

Added sentinel 1 information

@@ Line 21: / Line 21: @@
 ## ALOS, JERS, TERRASAR-X/TandDEM-X
 ## <nowiki>https://earth.esa.int/web/guest/pi-community/apply-for-data</nowiki>
-## <nowiki>https://earth.esa.int/eogateway/</nowiki>
+## [https://earth.esa.int/eogateway/ Earth observation gateway]
-## <nowiki>https://earth.esa.int/web/guest/pi-community/apply-for-data/3rd-party</nowiki>
+## [https://earth.esa.int/web/guest/pi-community/apply-for-data/3rd-party Earth Online 3rd party data products]
 # The [http://spaceportal.uwasa.fi/ space portal of University of Vaasa]
 # NASA data sources, for example [https://worldview.earthdata.nasa.gov/ NASA Earth data]
 # Commercial ones, [https://www.planet.com/pulse/planet-introduces-new-high-resolution-pelican-satellites-and-fusion-with-sar/ Planet], [http://syntheticapertureradar.com/category/spaceborne/satellite/airbus/ Airbus], [https://www.iceye.com/ ICEye] etc. You can test and learn with the free data but it’s limited.

Uwasa: Added more links

2022-02-09T07:59:50Z

Added more links

@@ Line 13: / Line 13: @@
 Some of the SAR satellite data is available from public sources
-* Data from all satellites from Copernicus program can be downloaded from [https://scihub.copernicus.eu/ SciHub]
+* Data from all satellites from [https://www.copernicus.eu/en Copernicus program] can be downloaded from [https://scihub.copernicus.eu/ SciHub], instructions for usage can be found from the [https://mooc.copernicus.eu/ Copernicus MOOC] course.
-* Data from many publicly open satellites can be accessed using [https://code.earthengine.google.com/ Google Earth Engine]
+* Data from many publicly open satellites can be accessed using [https://code.earthengine.google.com/ Google Earth Engine], and it can be also used for making and running your own algorithms in the cloud. One example is the [https://akinnunenuva.users.earthengine.app/view/nightlightstest night light test application].

Uwasa: Added more links

2022-02-01T12:58:41Z

Added more links

← Older revision		Revision as of 15:58, 1 February 2022
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	There are many SAR satellites in the orbit, such as		There are many SAR satellites in the orbit, such as

	* Two Sentinel 1 satellites from Copernicus program.		* Two [https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-1 Sentinel 1] satellites from [https://www.esa.int/Applications/Observing_the_Earth/Copernicus/ Copernicus program] of the [https://www.esa.int/ European Space Agency (ESA)].
			*[https://asf.alaska.edu/data-sets/sar-data-sets/alos-palsar/ ALOS PALSAR]
			*[https://www.iceye.com/ IceEye]
			*JERS
			*TERRASAR-X
			*TanDEM-X

Uwasa: Added somewhat text already

2022-02-01T12:52:47Z

Added somewhat text already

← Older revision		Revision as of 15:52, 1 February 2022
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	~~TBD~~		Synthetic Aperture Radar (SAR) imaging is an Earth Observation (EO) method, where a satellite sends radar pulses to the Earth and monitors it's reflections. The moving satellite forms so called synthetic aperture, which can be used for studying the signal reflections from different points on earth. The time of flight of signal provides a distance between satellite and the ground surface. Because the exact location of the satellite is known, the distance can be used for estimating Earth topography. On the other hand, the strength of the reflected signals carries information about the properties of the Earth surface.

			There are many SAR satellites in the orbit, such as

			* Two Sentinel 1 satellites from Copernicus program.


			Some of the SAR satellite data is available from public sources

			* Data from all satellites from Copernicus program can be downloaded from [https://scihub.copernicus.eu/ SciHub]
			* Data from many publicly open satellites can be accessed using [https://code.earthengine.google.com/ Google Earth Engine]

Uwasa: Created page with "TBD"

2021-12-09T13:30:05Z

Created page with "TBD"

New page

TBD