Questions tagged [sar]

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Preparing dataset for SAR pre-processing

I am working on Chandrayaan-2 lunar SAR data and have the Fully polarized, Single Look Complex SAR data, which is Slant Range Data Product. Along with it is an excel sheet with lat, long, incidence ...
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22 views

SAR GRD preprocessing workflow necessity

I was working on Sentinel 1 SAR GRD (EW mode) imagery from Copernicus when I came across this workflow here. Is it necessary for GRD products to pass through all steps of this workflow before they ...
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1answer
69 views

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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1answer
40 views

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

How to define those two SAR Technologies?
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31 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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1answer
16 views

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 ...
2
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1answer
181 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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31 views

ISCE Interferometry

I am looking for the method of doing interferometry from the software ISCE. I am interested in processing Sentinel 1, RadarSAT, TerraSAR, etc. data. I am new to using the ISCE Software. Is there ...
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45 views

Automatic water extent mapping from Sentinel-1 SAR using Otsu's method

var imgVV = ee.ImageCollection('COPERNICUS/S1_GRD') .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV')) .filter(ee.Filter.eq('instrumentMode', 'IW')) ....
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31 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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98 views

How to segment Sentinel 1 tif images (floating point) with mask images of 6 classes in keras using unet or any other segmentation models

I am trying to apply unet segmentation on processed sar tif file with the mask image of 6 classes but output of the model is showing only 3 classes and also how to generate predicted segmented images. ...
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23 views

Viewing components of complex ENVI .hdr Labelled Raster

An output of my InSAR analysis is an ENVI .hdr complex raster with data type 6. The data is stored as a real-imaginary pair of single-precision floats. QGIS can load the raster, but displays nan for ...
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1answer
47 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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19 views

Coregistration of PALSAR and Landsat-8

I'm working on forest biomass estimation with Alos-Palsar and Landsat-8 data for 2015. For this I need to coregister the scenes from Alos-Palsar and Landsat-8. I would like to know which open source ...
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2answers
246 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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0answers
19 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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105 views

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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1answer
85 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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1answer
36 views

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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1answer
47 views

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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1answer
777 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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1answer
336 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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2answers
180 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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0answers
89 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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1answer
92 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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1answer
58 views

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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0answers
41 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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1answer
215 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 ...
3
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0answers
373 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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1answer
109 views

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 ...
5
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1answer
312 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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1answer
2k 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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66 views

SAR processing - geocoding shapefile which is slant range

Is there any software (like snap, sarscape etc.) can be used to geocode shapefile (slant range) to shapefile (ground range) (like WGS84)? If yes, which data is need for that? By the way, the ...
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1answer
242 views

GDAL: Using gdallocationinfo on a rotated SAR image to get pixel value at Coordinates

Some information: I must not re-sample the image, the pixels are rotated, and the image opens in Arcmap just fine. now, there are 15 GCPs on the raster (which make the pixels rotate) Progress: 1.When ...
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2answers
2k views

How to mosaic multiple Sentinel-1 images in SNAP software?

I am trying to mosaic multiple sentinel sar images in esa snap software. The scenes are acquired from two adjacent tracks. I used the tool S1 slice wizard in snap under radar tool menu. But my images ...
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2answers
2k views

How to visualize inundation using Sentinel 1 SAR Data?

I am trying to visualize flooding after hurricane Harvey that made landfall on August 25-26 2017. Based on this video, I've been able to obtain the basics of Sentinel-1 SAR imagery. Sentinel 1 comes ...
6
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1answer
198 views

InSAR processing: why can't we just compute distances directly from time delays?

My question can be very basic, but even after studying quite a few tutorials on InSAR processing, I still do not understand one thing: if we know a wavelength, speed of light, a time delay it takes ...
2
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1answer
152 views

How to calculate an incidence angle raster for a radarsat 2 scene using gdal / python?

I want to make a raster band that gives the incidence angle for each pixel in a radarsat-2 scene. I know this is possible using the information given in the product.xml file (below), but I'm not ...
2
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1answer
348 views

Error in orthorectification of Radarsat-2 scenes with GDAL and RPC + DEM information

I am trying to use a DEM rational polynomial coefficient (RPC) information to orthorectify radarsat-2 images with GDAL 2.2.1. I have successfully done this with Orbview-3 images using the tutorial ...
5
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1answer
250 views

Understanding difference between collocation and coregistration?

I'm a little confused on this topic. I need to put 2 SAR images into same coordinate grid. In ESA SNAP tool, there are 2 options: coregistration: Radar->Coregistration->Coregistration collocation: ...
2
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1answer
107 views

SAR spectral signatures for oil spill detection from different sensors

I have a rather general question about supervised classification for oil spill detection. I want to apply supervised classification on the ESA SNAP dark spot detection tool results. My question is: if ...
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2answers
200 views

Sun-synchronus orbit for SAR satellite

I have been following the news about the launch of the PAZ satellite (a SAR imaging sensor). The orbit will be sun-synchronous. I know this is important for optical sensors to make sure they have the ...