Questions tagged [remote-sensing]

Collecting and interpreting information about the environment and the surface of the earth from a distance, primarily by sensing radiation that is naturally emitted or reflected by the earth's surface or from the atmosphere, or by sensing signals transmitted from a device and reflected back to it.

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Is there a way to filter out polygons/lines using geometry in QGIS?

I am currently working on a project to digitize utility data, however my input layer is not classified. I am currently using length of the features to filter out unnecessary lines/polygons. Is there a ...
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Calculate transition of different NDVI classes from pre and post NDVI in Google Earth Engine

My competency in GEE is quite low. I have calculated 2 NDVI layers (pre and post-disturbance NDVI). I have separated these NDVI layers into 4 classes according to NDVI values. Now I need to calculate ...
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QGIS plugin for reviewing image and label pairs for satellite image segmentation deep learning models

Does anyone know of a plugin or other offline tool, preferably but not necessarily implemented as a QGIS plugin, for reviewing and editing image/vector label pairs for satellite image segmentation? My ...
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Adding external data to NDVI Chart google earth engine To have Two line charts on the same plot

I am trying to add external data to ndvi chart on google earth engine in order to have both lines on the same chart. I have been able to plot them differently but not able to merge them. Here is my ...
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RMSE, and R2 based on 10 K-fold validation on Google Earth Engine

Could anyone help me here, I would like to calculate RMSE, and R2 based on the 10 k-fold validation. I followed the example, but I was not able to figure it out. // The following script is modifed ...
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Remove system start when plotting after calculating NDVI for shrubs and grass in Google Earth Engine using Copernicus

I have tried to select only shrubs and grass on NDVI but on plotting chart it shows this error. Here is the code. var feat =ee.Geometry.Point([33.15865673674562, -5.173302054347385]); var s2a = ...
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EarthPy plot scatterplot on top of plot_rgb

I am using earthpy.plot_rgb() for some satellite image because it works very well. However, I have the coordinates of a line that I'd like to plot on top of it with scatterplot, but I can't make it ...
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Approaches to distinguish bare soil from artificial soil in an urban context with Pleiades imagery?

My colleagues and I are trying to improve an existing landcover map by improving the distinction between bare soils and artificial soils (e.g. concrete, asphalt). We need a good detection of bare ...
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Why do I get an error when applying getInfo() in Google Earth Engine?

I'm working in an undergraduate project and just started using Google Earth Engine. Firstly, I need to filter some Sentinel-2 MSI images that cover my area of interest (a watershed with 55 km²) from ...
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Using images from different Landsat missions and Sentinel-2 for machine learning

I am doing some image segmentation using random forests on satellite imagery. The events I am trying to detect are somewhat rare so my training sets are very limited if I want to use Sentinel-2 ...
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Projection problem with VIIRS-SNPP Deep Blue Aerosol data in R

I am having some trouble with VIIRS/SNPP Deep Blue Aerosol (DBA) product in R. After post-processing the data, I am not being able to obtain the data in the region of interest (ROI), hence I checked ...
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Google Earth Engine - NDVI chart - projection error

Once I multiply NDVI and EVI values with 0.0001, I get an error that is shown below. So I can't get the chart. Error generating chart: Projection error: Unable to compute intersection of geometries ...
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How to download a mask layer as array from GEE?

I am trying to create a cloud mask for my image, which I successfully did with the following code: // Masking clouds -> binary array var maskInside = function(image, geometry) { var mask_outside =...
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Projection best practices for applying ML to large scale Earth Observation imagery [closed]

I come from a data science background, rather than GIS, but work in a domain where remote-sensed imagery is widely used; so I'm still learning some of the do's & don'ts when it comes to the 'right'...
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Reusing regression or machine learning model in subsequent years

I have collected high-resolution UAV imagery and leaf area index (LAI) plot data. I plan on creating a model which uses my ground-based LAI to establish a relationship or train my UAV imagery. I will ...
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Remote sensing for algae blooms

I was curious if anyone knows what index is good for measuring algae blooms from multispectal imagery. I have tried using NDVI with minimal success but I have heard that blue/green and blue/red also ...
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Difference between two Google Earth Engine functions

Do you know what is the difference between ee.Clusterer.wekaKMeans and ee.Clusterer.wekaCascadeKMeans?
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Dividing reflectance values of Sentinel-2 sets of bands using rasterio

I need to divide the reflectance values of a Sentinel-2 sets of bands. To do this, I have to divide each band by 10000 when I read in the band to write the stack. I have an example of my code snippet ...
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Is ground sampling distance (GSD) related to the sampling of the object we have on the ground or to the output that comes from the sensor?

I am studying the GSD for a remote sensing mission. I don't understand if the GSD is related to the sampling of the analog output generated by a sensor or to a given scene on the ground. My textbook ...
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Why do I get wrong NDVI, EVI values in crop monitoring?

I have been monitoring agriculture lands with Sentinel-2 S2MSI2A data. I'm calculating NDVI and EVI for the vegetation. The NDVI values are slowly increasing because the growing crops which is look ...
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How to distinguish never deforested from never forested using Hansen forest data

The Hansen Global Forest Change dataset has a lossyear band, for which 0 values mean no loss. However, no loss can either mean: The pixel was forest in the beginning of the sample (2000) and still is ...
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Displaying raster data information in specific coordinates

I am currently trying to figure out how to retrieve the information in a specific point in QGIS. I opened a netcdf file containing information about chlorophy-a concentration in the Mediterranean Sea. ...
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DEM coordinates do not align other data layers

I recently downloaded Original Product Resolution (OPR) Digital Elevation Model (DEM) data for some analysis. The DEM does not align with any of the other data sets I have for the area. I have ...
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Changing boundary color and increase thickness of a feature in Google Earth Engine

I'm trying to find elevation using GEE, but I want to set boundary thickness for each country for better representation. How can I do this? Here is the link for code. You can see when two countries ...
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Vegetation classification for aerial photography in QGIS

What I need to do is to use QGIS, for vegetation classification of some older and newer Aerial Photography. In the past we have used ERADS Imagine but I have seen that there is some plugin developed ...
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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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Optimization of code for GEE charts

I'm extracting spectral signatures from Sentinel 2 imagery. I need to plot the chart for a certain target area showing the signature of the area and that one of a different reference area. Then I need ...
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Reducing a region in Google Earth Engine error for NDVI classification

I'm trying to classify a region using NOAA but after input the date to classify then it does not generate a chart and shows the error of region and chart. The error for the region is this: Line 151: ...
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Enhanced Vegetation Index Value meaning

I calculated the NDVI and EVI for a forest area. I found information to interpret the NDVI values. But I wonder how to interpret the EVI values. I read Huete et. al (2002: 209), the common source. And ...
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Easy way to create cloudless mosaic

Is there an easy way (or easy access database) to create cloudless mosaics for a country (e.g. Germany) from Sentinel-2 data? I found this ressource: https://registry.opendata.aws/sentinel-s2-l2a-...
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Satellite sun-synchronous orbits and local acquisition time

I have two questions about sun-synchronous satellite orbits. Firstly, I know that equator crossing time for a particular platform is approximately 10:30 – 11:00 local time (descending node). My study ...
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Calculate and extract layer of NDVI change in Google Earth Engine

My experience and expertise in Google Earth Engine are super low. My study area is Sundarban, Bangladesh. I have 2 NDVI from 2 years (2016 & 2017). I want to find the vegetation change by ...
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2 votes
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Create Function to a RasterStack

This is the function that I want to create: Erosivity_Factor = 1.74 * log[sum(montly²/annual)]+1.29 I have solved it using a loop: # Reproducible RasterStack with 12 layers Monlty<- stack(lapply(1:...
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Do I have to do any preprocessing on Landsat 8 Surface Reflectance data sets in Google Earth Engine?

I am working on calculating NDVi and EVI indices from different years (50 year time period) and comparing them. I have a few questions regarding the datasets that I have found on Google Earth Engine (...
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How to interpret snowmelt timing script from Google Earth Engine?

I have used this script from Google Earth Engine (GEE) to define the snowmelt timing in Fenoscandia. I am not entirely sure how the mask works for setting the minimum days a pixel has to be covered by ...
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Are Landsat satellites exactly sun-synchronous?

Sun-synchronous satellites are known to pass over any given point of the planet's surface at the same local mean solar time (link-to-wiki). Landsat is one of these sun-synchronous satellites. I'm ...
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Supervised Classification: determining Training & Validation Data Sample Sizes [closed]

How does one determine Training & Validation sample sizes for Supervised Classification? My scenario: I'm using a previous year's classified map (2019) as an "a-priori" guide for picking ...
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Identifying outliers (not considering spatial relationship) in time-series data

The data I am working on is plant canopy cover (percentage within polygons (0-100%)) estimation from drones. This was collected over the course of 17 weeks. I was thinking on detecting outliers (not ...
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How to calculate number of pixels in a TIFF

I have three TIFFs that are grayscaled. There is only one pixel value, but two very clear different "colors" (majority of pixels are black, some are white). How do I separate these pixels ...
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Creating formatted chart for Confusion Matrix using Google Earth Engine

I was curious how to create a formatted Confusion Matrix: (https://developers.google.com/earth-engine/apidocs/ee-confusionmatrix) I've completed my Supervised Classification, and I've created a ...
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What sensor data is required to georeference remote sensing images?

The start-up I work for is planning to capture remote sensing imagery from cameras on-board our stratospheric balloons. We would like to be able to georeference the images we capture. If it is ...
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GEE error: ndvi.filterDate is not a function

I'm trying to find area covered by plants on my study area, but I'm getting this error: ndvi.filterDate is not a function This is my code: // Define a region of interest (i.e. an imported shapefile ...
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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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Accessing historical precipitation data outside of GEE

I'm looking for historical and also present climate data for some polygons I have. I would like to be able to access rainfall data for these points. I cannot use GEE and was struggling to find a good ...
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Sentinel-2 L2A metadata XML

I am trying to select Sentinel-2 L2A scenes that have low cloud cover. How should I interpret the difference between these three types of cloudy pixel % values captured here? I made this image based ...
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How can I cover an AOI with a subset of image extents?

I’ve been experimenting with a problem that I have not found a friendly and simple solution for yet. Curious to know if any of you have already solved this problem. Given a AOI and a set of image ...
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Landsat 8 Collection 2 (C2) Level 2 Science Product (L2SP)

I am exploring data sources for land surface temperatures (LST) for summer 2021. From Landsat 8 Collection 2 Surface Temperature (https://www.usgs.gov/core-science-systems/nli/landsat/landsat-...
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Creating Claslite-compatible Google Earth Engine images

If you've used Google Earth Engine outputs to create inputs to Claslite, how did you export your images from GEE and load them into Claslite? The website claims Claslite is compatible with GEE files, ...
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3 votes
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Landsat 8 appears to be "greener" than Landsat 5?

I noticed something strange in my NDVI time series. Here I plotted NDVI for some geometries of interest in European countries between 1985 and 2020. You will see there is a noticeable jump in NDVI ...
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I couldn't find Landsat 5 scene starting from 2002-08-04 to 2008-06-01

I am searching for Landsat 5 TM image from 2000 to 2012 in Earth Explorer Web site (https://earthexplorer.usgs.gov/). However, I couldn't find any scene in my study area starting from 2002-08-04 to ...
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