Questions tagged [sar]
The sar tag has no usage guidance.
42
questions
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19 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 ...
2
votes
1answer
61 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 ...
0
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1answer
36 views
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28 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 ...
0
votes
1answer
15 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
votes
1answer
135 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 ...
0
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0answers
17 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 ...
0
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0answers
39 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'))
....
1
vote
0answers
26 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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0answers
63 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. ...
0
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0answers
20 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 ...
1
vote
1answer
41 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 ...
0
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0answers
18 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 ...
0
votes
2answers
155 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 ...
2
votes
0answers
18 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 ...
1
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0answers
80 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 ...
1
vote
1answer
65 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 ...
0
votes
1answer
35 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 ...
0
votes
1answer
41 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, ...
0
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0answers
31 views
Take ROI for Raster image in Python?
Actually, I am able to plot raster (SLC) image in Python but I'm having issues with creating ROI tab. Basically, I want to take different ROI on that same image in Python. What could be wrong?
Using ...
1
vote
1answer
606 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 ...
8
votes
1answer
320 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.
...
2
votes
2answers
154 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 ...
1
vote
0answers
84 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 ...
4
votes
1answer
84 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....
0
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1answer
49 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 ...
2
votes
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 ...
0
votes
1answer
213 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
votes
0answers
328 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 ...
0
votes
1answer
100 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
votes
1answer
238 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 ...
6
votes
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 ...
0
votes
0answers
65 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 ...
0
votes
1answer
234 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 ...
3
votes
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 ...
7
votes
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
votes
1answer
191 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
votes
1answer
142 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
votes
1answer
328 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 ...
4
votes
1answer
223 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
votes
1answer
102 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 ...
0
votes
2answers
192 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 ...
