Questions tagged [sar]

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DEM from Sentinel 1 C-band SAR

I have been using the standard protocol (ESA/ASF) to generate DEMs (actually DSM which is what S1 C-band gives) from Sentinel-1 C-Band SAR tiles. My locations are in the Eastern Himalayan foothills (...
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1 vote
1 answer
36 views

Radar Vegetation Index Using Google Earth Engine

I tried to calculate Radar Vegetation Index with Google Earth Engine using the code given below. The Value of RVI should range between 0-1. but I'm getting following error Code: var RVI= function (...
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Problems with phase unwrapping unsing SNAPHU

I am trying to generate a DEM using a pair of Sentinel-1 images by following this tutorial. I am running into the following problem in the Phase unwrapping step using SNAPHU. There are some noticeable ...
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-3 votes
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Orthorectification Sentinel - 1 Geocoding Guide [closed]

For orthorectification of SAR Image, I am following backward geocoding algorithm provided in Sentinel-1 SAR Geocoding Guide While computing the range and azimuth index from DEM traversal, the obtained ...
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Sentinel 1 stripping artifact

I am processing a S1 SLC image as follows: Read>Apply orbit file>S1 TOPS Split>Radiometric Calibration (complex)>S1 TOPS Deburst>Polarimetric Speckle filter>Terrain correction (Range ...
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Are there any open source L-band SAR missions that have good spatial coverage and temporal resolution?

I am looking for current L-band SAR data that is easy to download for free, with good spatial coverage and temporal resolution. Does anybody know if such datasets exist?
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Band used for deformation estimation using In-SAR

Which polarization of SAR data (C-band - Sentinel-1A) shall I use to get a better deformation map of a mountain terrain - VV or HH?
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28 views

Geocoding Moon SAR image using corner latitude and longitude

I have tried geocoding the SAR image of the Moon. I have the latitude and longitude information for the four corners. In Python, I am using the GDAL command to geocode. !gdal_translate -a_ullr -1....
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Incidence angle meta-data for Sentinel 1 GRD on AWS

I have seen how incidence angles can be obtained for Sentinel 1 sigma-0 backscatter when processing from the SLC product with SNAP. However, I want to use the pre-processed GRD product. I couldn't ...
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28 views

Magnitude and Amplitude in SAR are different?

Are these two terms, amplitude and magnitude of radar signal, the same? If they are different what are each one? I have been reading some papers and some authors seem to use them interchangeably, ...
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27 views

Terrain correction TerraSAR-X images

I am trying to perform terrain correction on a SAR image using GDAL. I tried using simple gdalwarp, but the accuracy is not enough for me, so I decided to use: gdalwarp -multi -wo NUM_THREADS=ALL_CPUS ...
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1 answer
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Calculate water area of Sar images of Google earth engine

I use this link to extract surface area of water bodies from SAR images Google Earth Engine ROI area falling outside/partial coverage by Sentinel 1 Tile But now i would like to calculate the area of ...
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Terrain correction in SAR image

I am new to the gdal utility. Using DEM data of the Moon, I am trying to perform terrain correction on SAR images. I have a DEM file and SAR data into tif file format. Both DEM and tif file are in ...
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1 vote
0 answers
140 views

Create GeoTIFF from data array using the original file metadata

I received a .mat file which is the processed data from a Radarsat-2 scene. My goal is to transform this data array into a GeoTIFF file, onto the same projection as the original Radarsat-2 image. I ...
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Using Sentinel-1 L1 Azimuth Time

In the metadata included in S1 L1 products, in each geolocationGridPoint it is included the "azimuthTime" for each point. How can the azimuthTime be different for each pixel? Shouldn't the ...
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1 vote
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The nature of SAR pixel value VS. of panchromatic pixel value

When we compare sentinel-1 SAR orthorectified 8-bit image vs a very high resolution panchromatic 8-bit image, the panchromatic cells are a resemblance of signal amplitude in an 8-bit scale (0-255). ...
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2 votes
1 answer
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Plotting GeoTIFF using Cartopy

I am trying to plot a SAR image, in TIFF format and containing the following projection arguments, using Cartopy. PROJCS["WGS 84 / EPSG Norway Polar Stereographic", GEOGCS["WGS 84",...
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Different plot for individual in Google Earth Engine without writing plot lines multiple times

For example, I have three polygons over the NDVI layer so I want three different charts, and if 100 then 100. I don't want one chart with different lines. I want to avoid writing the same plot chart ...
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What are these rectangular structures on SAR image?

I'm looking through SAR images and I found this (kindly refer to SAR image below). And here's what it looks like on Google Satellite. As you can see, there's no similarly shaped structure found on ...
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How to create change/no-change map?

Recently I've been working on polarimetric SAR images. I have two images from two different timestamps of some agricultural areas. Based on these two images, I want to create a map telling which parts ...
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1 vote
1 answer
85 views

How does one geocode 2 points with same Lat-Long but different heights?

I am working with Ground-Based SAR (radar) data. My task is to geocode the image. I am new to Geocoding. I was reading through various geocoding approaches that explain how to convert latitude, ...
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4 votes
1 answer
96 views

Averaging shapefiles using QGIS

I am working with the shapefiles from the OSPAR on fishing intensity. I have the shapefiles from 2009 to 2017 I would like to "merge" them in order to obtain a mean value for all the ...
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Reason behind the white line on a SAR image?

So I'm reading a paper about satellite data and SAR imaging and I came across this image. I couldn't help but notice this white line running from top to bottom of this example image. Does anybody know ...
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1 vote
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SLC IW Visualization in Python/Matplotlib

I'm hoping to add Sentinel 1 data to a tool I'm building. Preferably I would like to use GDAL to load the image, and extract the pixel values from the image. I realize that the pixel values are ...
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1 vote
1 answer
697 views

Creating composite RGB images from Sentinel 1 channels

I would like to create a RGB image using Sentinel 1 data. It appears the standard way is to assign VV, VH, and VV/VH for the R, G, and B channels. I do, however, have a two questions. One. It is ...
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2 votes
1 answer
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Reprojecting raster changes pixel scale (makes it darker)

I have an HH polarised SAR image as follows: This is how it looks in QGIS in the default EPSG:4326 projection. Now I would like to reproject this raster to ESRI:102020 (South Pole Lambert Azimuthal ...
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1 answer
178 views

What is the difference between InSAR and PolSAR? [closed]

How to define those two SAR Technologies?
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1 answer
167 views

Steps to view SAR imagery (SICD) in QGIS

I would like to view SAR imagery in a SICD file in QGIS. I am able to load the file and view it as a singleband gray image, but the image does not look correct - features are not detectable and the ...
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Error in visualising MDPI band

I am trying to stack a 3 band image (2 NDVI bands and 1 MDPI band). There is some error when I am trying to visualise the MDPI band (which is appearing as masked in the Inspector) and hence the ...
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2 votes
1 answer
368 views

Problem with Sentinel 1 images in Google Earth Engine

I am trying to apply Otsu algorthm to S1 images starting from its launch to till date on my study area for waterbody mapping. I perform otsu without applying any date filter for Satellite pass so I ...
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1 vote
1 answer
95 views

Error occurring when converting to dB during the python-based classification

I am trying to perform an object-based classification using a python-based script with rsgislib. Although, when converting to dB, an error is appearing. Any ideas why is this happening? Create and ...
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1 vote
1 answer
67 views

Sentinel-1 image backward

I have this problem with my images of the Ross Ice Shelf: This is an image that has been Radar - Radiometric- Calibrate- Amplitude_HH - Gamma0 followed by Speckle Filter. This is what happens when I ...
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2 answers
920 views

Sentinel-1 GRD: which intensity to use (VV, VH, or combination of these)?

I have Sentinel-1 IW GRD images; for each capture date, one geotif with the VV and one with the VH values. I assume these are intensity values for the co-polarization and cross-polarization bands. To ...
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2 votes
0 answers
29 views

Complex SAR values in Interferogram

By what I understand, a "standard" slc from a SAR has complex values for each pixel. Here the phasor consists of the magnitude and the relative phase. What I don't understand is the complex nature of ...
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1 vote
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Changing contrast of GeoTIFF using Python

I have a GeoTIFF image that I can split into the 4 layers. Now I wish to increase the contrast of the layers and stitch them back together. However when I use numpy to do this, I am unable to increase ...
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1 vote
1 answer
183 views

How can I filter my image collection based on incidence angle in SAR?

Im completely new to SAR, and Im trying to understand the basics. Im studying a small area in Google Earth Engine, and Im making timeseries of water pixels with SAR imagery. However, I observed ...
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1 answer
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The image collection doesn't correspond to my interactive map (Sentinel-1 in Google Earth Engine)

I want to classify water pixels with Sentinel-1 in Google Earth Engine, and I'm using this code I found here: https://mbonnema.github.io/GoogleEarthEngine/07-SAR-Water-Classification/ However, in my ...
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0 votes
1 answer
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QGIS view raster with no CRS without on the fly reprojection

I have RADARSAT-2 imagery which is georeferenced with Rational Polynomial Coefficients (RPCs), but is not orthorectified. QGIS will reproject/resample the raster to a defined CRS like EPSG:4326, ...
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3 votes
2 answers
1k views

Calculating water occurrence of Sentinel-1 images in Google Earth Engine

I would like to derive the occurrence of surface water bodies from Sentinel-1 image collection in the Google Earth Engine.In my example I could already compute the water mask using Otsu’s method for ...
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8 votes
1 answer
400 views

Layers misaligned in QGIS

I have two National Imagery Transmission Format Standard (NITF) files loaded into QGIS 3.10 and they should be the same coordinate system but for some reason I cannot figure why they are not aligned. ...
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2 votes
2 answers
305 views

Manipulating Sentinel-1 SAR Imagery to get Pixel Information

For S1 SAR imagery data, how would I go about accessing the data of individual pixels? I need to analyze pixel intensity based on their lat and lon coordinates. I know this information is viewable in ...
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1 vote
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130 views

SAR calculating distance between 2 points

I am playing around with ESA's SNAP software and Sentinel-1 data and I was curios if it is possible to measure the ground distance between 2 points in a radar image. For example let's say that I am ...
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4 votes
1 answer
154 views

Sentinel-1a real azimuth resolution

I was exploring this satellite's payload characteristics on ESA's website and I saw that it's azimuth resolution varies a lot. For example azimuth resolution for IW mode is 22m (https://sentinel.esa....
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1 answer
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Using GDAL for reading calibration and annotation data set

I have a Sentinel-1 .SAFE data which provides a wealth of information through .tiff images and also .xml files containing annotation and calibration information. Following the instructions in the ...
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2 votes
0 answers
59 views

Synthetic Aperture Radar data format

I'm trying to learn about the SAR image formation process. From reference such as Carrara's Spotlight Synthetic Aperture Radar book, it appears that after various compensations, a direct 2D fft can ...
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0 votes
1 answer
287 views

Google Earth Engine - Blend Sentinel-1 SAR Images?

Does anybody know why I am getting these strips across my Sentinel-1 images and how to fix it? I am using multiple images over Mozambique between January 1st and January 13th. I want to use this ...
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3 votes
0 answers
504 views

Histogram matching in Google Earth Engine?

Does anyone know if there is a more GEE-friendly way of achieving this? I'm experimenting with S1 SAR image histogram matching in GEE and was wondering if foremost the code can be improved. Read here ...
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0 votes
1 answer
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Calibration annotation data for Sentinel-1 images downloaded from Sentinel Hub?

I received some Sentinel-1 tiff images that were downloaded via the WCS service, so they're just the tiff files, not the full SAFE-format products. They're for the IW GRD product, and my ...
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5 votes
1 answer
721 views

What do horizontal (H) and vertical (V) polarization mean for satellite radar?

I'm reading about synthetic aperture radar (SAR), and one of the basic concepts is that the transmitted and received signals can have "horizontal" (H) or "vertical" (V) polarization, but I can't find ...
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7 votes
1 answer
3k views

SAR processing using Python

I would like to batch process Sentinel-1 images in Python. Previously I have used SNAP (Sentinel-1 Toolbox) to apply Calibration, Multilooks, Speckle Filters, Terrain Correction and then export as a ...
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