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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6 views

Confusion about “alpha” band for MODIS Aqua

I'm working with modis:09:CREFL data for a harmful algal blooms paper, and I am trying to figure out how to call the chlorophyll-a band, which I believe is the "alpha" band, but I'm not sure ...
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26 views

How to rotate orthographic projection using basemap

I'm working with the python basemap library and am plotting data over Greenland using an orthographic projection. However I find that due to the location of the coordinates, basemap auto plots the ...
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8 views

Sensing data Sentinel-3 time zone

I have a question about sensing data time zone from https://scihub.copernicus.eu/dhus/#/home. In which time zone copernicus provide for us data ? For example on image we can see Sensing Date Is it CET ...
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18 views

How to convert large size hyperspectral from tif to lan

I tried to convert hyperspectral from .tif to .lan format. There are three file with size about 1.5GB , 750MB and 200MB respectively. I use this code from osgeo import gdal src_fname = 'file.tif' ...
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1answer
17 views

Correcting Worldview-3 data to ground reflection/bottom of atmosphere with open source?

I have some worldview-3 imagery that needs to be corrected from digital numbers to actual reflection values (preferably bottom-of-atmosphere). But the tricky part is I am looking for open source ...
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1answer
26 views

Optimal Sentinel 2 Bands combination for NDMI

I want to calculate NDMI (Normalized Difference Moisture Index) using Sentinel 2 bands on QGIS. I am not sure if right formula is B8-B11 or B8A - B11. Band 8 seems to give better results but on the ...
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1answer
40 views

Time Series Extraction of Modis LAI product (every 3 days a new satellite image) in small study area

At the moment I am struggling with a time series and the extraction of MODIS LAI data. I am using the band "Lai" from MODIS/006/MCD15A3H. My study area is small, so presumably, since the ...
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Calculate and plot the feature importance of the input dataset of a random forest classification within Google Earth Engine (GEE)

I run a random forest classification for agricultural land use and other land cover classes (12 classes). My dataset for 2019 consists of a Sentinel 1 and Sentinel 2 monthly time series, statistical ...
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13 views

Sentinel-2 active fire detection service

I'm looking for a Sentinel-2 analogue of the FIRMS service (Fire Information for Resource Management System), which provides the location of active hotspots. The low spatial resolution of MODIS and ...
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1answer
36 views

Fulfilling removed cloud area with free cloud data in Google Earth Engine

I have completed doing cloud removal with Landsat image (in this case is Lansat 8) in the Google Earth Engine. Of course the result of this process is the cloud pixels become no data, consequently the ...
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15 views

SNAP Sen2cor Correction

While applying sen2cor correction in SNAP on sentinel-2 L1c product i receive this error "cannot find L2A data strip directory" how i solve this error
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27 views

Why are my forest areas orange and non-forest areas green in Google Earth Engine?

I'm doing GEARS' 3rd lab tutorial on Remote Sensing in Google Earth Engine. I calculated the NDVI of an area in Batchellor, Australia. The result is a black and white image so I added a color palette. ...
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Data for Sentinel-2 L2A product (suddenly) missing in GEE for certain dates

This code returned imagery for two date ranges previously. It suddenly stopped working for the 2nd date range (2018-06 to 2018-09). I explored setting the cloud cover threshold up to 99 and searching ...
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1answer
28 views

How can the maximum temperature (tmmx) band in the TerraClimate GEE dataset be interpreted?

This question was already asked here. But there was no correct answer. link I'm using the precipitation, maximum temperature (tmmx) and soil moisture in the TerraClimate dataset in GEE. I cannot find ...
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18 views

Identification of cloudy days based on Net Radiation data

How can I identify that a particular day is cloudy or clear sky based on the daily time series of Net Radiation (calculated at FluxNet/AMERIFlux sites)? I read somewhere that clear sky radiation has ...
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30 views

Landsat imagery corrections

I have downloaded Landsat collection 1 Level 1 imagery (Landsat 4,5,7 and 8) from https://earthexplorer.usgs.gov/. I would like to know that do we have to apply some conversions or corrections before ...
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33 views

Issue while creating dataset mask for Landsat 7 ETM+ band data by using rasterio

I am trying to create dataset mask of a particular band of Landsat-7 (B2) & Landsat-8 (TIR) data and then plot the same using the following code: For Landsat-7 Band-1:- import rasterio import ...
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1answer
52 views

Getting .argmax() in a list appended to an image collection: Google Earth Engine

I have appended a list of elevation data to a filtered image collection in GEE as metadata. I now want to find the position of which elevation (e.g. 25 meters) has the highest pixel count using ....
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1answer
29 views

Explanation on band conversion from radiance to reflectance final value

I've watched few video on conversion of radiance to reflectance for landsat band, most of them recommended to use formula below to to make sure the final reflectance value lies in between 0 to 1. My ...
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24 views

The extraction of the Sentinel-1 backscattering coefficient

I want to do some calculations with the backscatter coefficient of the Sentinel-1 satellite. Do I need to filter the raw data(using mean or sigma Lee) on GEE?
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1answer
24 views

Making Images in Collection Binary Based on Threshold

I am trying to make every image in a collection into a binary image based on whether it's band's pixel value is higher or lower than a certain threshold. For instance, if an image's pixel in a ...
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31 views

Input image does not match with signature file in supervised classification

I have a issue in supervised classification on ERDAS IMAGINE. When ever I performed supervised classification it gives a warning message. It says: iInput image does not match signature's image ...
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1answer
47 views

Relation between spatial resolution and object size in satellite imaging

Is there a general rule of thumb that relates the ability of satellite remote sensors to resolve an object and the spatial resolution of the sensors? For example, a whale that's 15m in length and 7-8 ...
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10 views

Where can I find reflectance / VI data for crops for different dates across their growing season?

I have been trying to find literature values for reflectance of soybean for different dates along the growing season (I am specifically interested in 30, 60 and ~120 days after planting - so the V3/V4 ...
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45 views

How to find the Minimum value for the Dark Object Subtraction in ERDAS?

I have a Landsat 7 Image with MTL file showing minimum value as 1 and the maximum value is 255. The water pixels show a range of 63 to 74. In the image, there are a few pixels that have a value of 1, ...
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13 views

TIMESAT Quality Data

I am trying to analyse time-series images from MODIS (MOD13Q1) in TIMESAT to clear the noise and get an output. With EVI images I got also QA. I have to use it because there is often a cloud cover in ...
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25 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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33 views

Viewing Google Earth Engine source code — Landsat TOA

I am working on a project looking at satellite calibration, and would like to see how Google Earth Engine performs ee.Algorithms.Landsat.TOA(image). I know that they incorporate the metadata ...
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1answer
70 views

GeoTIF becomes super large by joining two grid bands (geotiff)

I have two raster tapes (GeoTIFs) that I want to merge into one GeoTIF with two bands. I used this command in the shell: gdal_merge.py -separate -o myoutput.tif *.cropped.tif, which was shown here. ...
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1answer
33 views

Integrating RGB image and nDSM data [closed]

How can I integrate RGB image and nDSM data provided in the dataset (ISPRS Vaihingen) that I want to use in a multimodal deep learning based semantic segmentation method? Can anybody provide a Python ...
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1answer
30 views

Understand values for Landsat 8 surface reflectance image

What do the numbers represent when you download an image, in my case Landsat 8 OLI TIRS surface reflectance. Are they DN numbers or reflectance values? If the image is not surface reflectance product, ...
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1answer
52 views

Merge neighboring image tiles into a single image

I have a set of satellite image tiles from Bing Maps (info here). The tiles' names specify tile coordinates within the tile system and zoom, e.g. 156608-142775-18.jpg. An example set of tiles: ['...
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19 views

Pixel-based image classification (Orthoimage or Raw image?

I am studying image classification and wanted to produce some land cover maps. However, i can not seem to find resources that states whether you need to geometrically correct (orthorectification) your ...
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21 views

Do Sentinel-2 L1C data downloaded from USGS Earth Explorer consist of reflectance values or digital numbers?

I was wondering if Sentinel-2 L1C data downloaded from USGS Earth Explorer consist of reflectance values. And is it necessary to use reflectance values for time series analysis of Sentinel-2 ...
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16 views

How to aggregate properly 8-days MODIS ET to a monthly ET?

I am looking for a robust method to aggregate the 8-day MOD16A2 (or MOD16A2GF) ET_500m values to monthly ET. Since ET_500m and PET_500m, are the summation of 8-day total water loss (0.1 kg/m2/8day). I ...
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1answer
67 views

Image (band) interpolation

I have a set of sentinel 2A images. I eliminated those that contained too many clouds, and then I created a cloud mask using cloud probabilities and Otsu thresholding method to eliminate cloudy pixels ...
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20 views

Ground Truth Data for India [closed]

I'm starting to get involved in a humanitarian project to understand crop-type and crop-yield in India to identify areas where they may be food shortages. The current approach for this project is to ...
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14 views

Sample strategy to model continuous variable from conglomerate ground sample units

I´m using data from the Brazilian national forest inventory to model forest canopy metrics with Landsat imagery. The sample units have this conglomerate configuration (picture), which creates a ...
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1answer
95 views

Google earth engine - set null band values as zero

I have a function which assigns a score depend on the value of a band, which I then map to an image collection. However, in some cases, I have null values, where no value is given. In these cases I'd ...
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1answer
144 views

Converting a FLIR image CSV to TIFF using Python

I have a geolocated CSV file containing one lat, long coordinate for the entire thermal image. I would like to convert this CSV to a TIFF using Python so that each pixel contains a temperature. All ...
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2answers
53 views

Interpretation of NDVI values

This might be a trivial question, but please bear with me. So I am using python and Sentinel images and I want to calculate NDVI, which is (NIR-RED)/(NIR+RED). So in the case where the final result ...
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1answer
21 views

Georeferencing bands at first then calculating NDWI, or, calculating NDWI at first and then georeferencing it

I want to get NDWI from MODIS mod021km as GeoTIFF files. As far as you know, MODIS images are not georeferenced and the point is georeferencing these imagages is a little bit inaccurate (because of ...
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48 views

Landsat 8 extracted pixel values for up North: 'pixel_qa' value of 322

I am trying to get landsat reflectance values corresponding to field plots spread all over Finland using the Google Earth Engine. As you know, Finland is up North, between latitudes of ~60 and 70 ...
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1answer
74 views

Extract landsat pixel values over plots with measurement dates

I am trying to get landsat reflectance values corresponding to field plots spread all over Finland in Google Earth Engine. Each plot is small, hence is represented by a single point (lat, lon). It ...
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12 views

Unsupervised pixel classification in ArcGIS Pro 2.4.0: ISO cluster will not let me classify image into three classes

I am using ArcGIS Pro 2.4.0, and am attempting to classify a field into a schema with three categories: Leaves, Shadows, and Soil. Here is a sample of the original RGB image: Through supervised ...
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19 views

Visualizing True Color Remotely Sensed Images

I am following this tutorial (which is also on GitHub) and I can't seem to understand this line of code: np.clip(eopatch.data['BANDS'][closest_date_id][..., [2, 1, 0]] * 3.5, 0, 1) I am guessing ...
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1answer
200 views

Empty geometry error in GeoPandas dataframe

I want to reproject my ground truth data (land reference map) to UTM. # Load Reference Data (reference map = ground truth data): labeled vector data in a shapefile (crops in Jendouba) LULC_filename = ...
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34 views

How to predict the whole image through trained classifier and visualize it as classified landuse and landcover image(LULC)?

I am working on LULC classification of sentinel-2 image(4-bands) using Machine Learning algorithms.I split the whole image into 64*64 patches and assigned class label(builtup,barren land,water and ...
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1answer
60 views

Sentinel-2: Resampling Spatial Resolution

Does resampling spatial resolution possible to do for all of the Sentinel-2 products, especially Level-1C? For instance, I want to uniform B1 - B12 spatial resolution to 20m. I just want to confirm it ...
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1answer
37 views

Sentinel-2 images

I am going to use Sentinel-2 images for crop type classification, and I am new to remote sensing. I want to know if there is an added value when using both L2A and L1C images. From what I understand, ...

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