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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24 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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1answer
22 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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10 views

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
20 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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1answer
146 views

Mask clouds across multiple images using Google Earth Engine

I Have multiple Landsat8 images at the same place in different years. I want to have a cloud mask for each image, then merge the mask so that all images will be masked with a same aggregated mask. I'...
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13 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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1answer
343 views

Landsat level-2 NDVI valid range with saturation

I have Landsat level-2 NDVI tiles I am using in ArcMap 10.4.1.; however, the level-2 NDVI data in ArcMap ranges from -5,189 to +20,000. The spectral image product guide (which I've linked) says that ...
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1answer
106 views

Unable to download VIIRS images with GIBS API and gdal_translate

I'm trying to download some VIIRS images from GIBS API. I'm using gdal: gdal_translate -projwin 19.07 42.16 28.39 34.5 -of "GTiff" "viirs.xml" "VIIRS_SNPP_DayNightBand_ENCC.tif" The viirs.xml file ...
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2answers
498 views

Computing MNDWI for Sentinel 2 Images in Google Earth Engine?

MNDWI is the normalized difference of Green Band and SWIR Band. In LANDSAT both are of a similar resolution i.e. 30m. In the case of LANDSAT var landsat8 = ee.Image("LANDSAT/LC08/C01/T1_RT_TOA/...
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28 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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1answer
25 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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25 views

Export feature collection after being flattened

I'm trying to export a feature collection of feature collections after being flattened. I cannot get the collection exported with the columns appended (in return value) and just flag an error with '...
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1answer
30 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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2answers
53 views

Integrating Landsat ETM+ and OLI surface reflectance data

I want to do a time-series analysis on Landsat surface reflectance data for an extended period of time (2005-2018), which requires integration of Landsat 5, 7, and 8. Is there any procedure to make ...
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1answer
46 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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3answers
1k views

Landsat 8 Band Value Range

I'm confused as to the range of brightness values associated with Landsat 8 Bands. I know that for Landsat 7 and below it has always been 0 - 255 but some of the literature indicates that Landsat 8 ...
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0answers
21 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
20 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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2answers
2k views

ENVI band math incorrect values

I'm attempting to calculate vegetation indices in ENVI 5.2 using level-2 AVIRIS data in band math. The indices I'm working with are Vogelmann Red Edge 2, normalized difference red edge, and red edge ...
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20 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
832 views

Extract Pixel Values for Multiple Polygons and Images

I have 21 polygons and for each polygon I want to extract the pixel values inside them for Sentinel 1 images from 2017-01-01 to 2017-06-30. The example below shows how this is done for one polygon. ...
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1answer
74 views

Merging multiple satellite bands for science data set rasters?

I am using MODIS satellite imagery data for one specific derived band. The problem I am running into is that it is a MCD19 SDS layer, which contains different bands for each orbit overpass at a ...
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29 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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1answer
33 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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1answer
113 views

Dataset description AREA_OR_POINT

What are the differences between these two options in satellite image metadata?
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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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1answer
927 views

Landsat level-2 data comparison

I'm doing a temporal analysis of NDVI and temperature over 17 years, necessitating data from Landsat 5,7, & 8. I'm interested in using level-2 Landsat data available from https://espa.cr.usgs.gov/...
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32 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
69 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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2answers
180 views

Min and Max for each image of NDVI to calculate Em and LST

I am working on my script to calculate LST for all the images in the collection separately and then use the calculated LST to estimate Mean Annual LST. I have calculated NDVI for each image, and the ...
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1answer
71 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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1answer
28 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

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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18 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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0answers
18 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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1answer
80 views

How to modify MODIS subset function to download product for a specific region and time period?

I am trying to assess the land cover change that has occurred over East Asia over last 18 years only in winters (Oct-Jan) for which I want to use MOD13Q1 dataset of modis from 2000-2018. I am using ...
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1answer
43 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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14 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
54 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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19 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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1answer
68 views

Dealing with NAN values in my training dataset

I am new to remote sensing. I am working on a project where I need to perform land use land cover classification. For such a task I want to use machine learning (python). My features contain 'BANDS' (...
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1answer
48 views

Reading .tiff data using Python

I got none type while trying to open those tiff data. What issue could it possibly be? I tried this: import glob images_tiff = [] for im in glob.glob(os.path.join(data_path, "*.tiff")): im = ...
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1answer
69 views

Python code speed execution problem

I am trying to retrieve data from 324 eopatches I sampled beforehand. Patches are basically numpy arrays as explained in this documentation EOPatch. This is an example of the content of a patch after ...
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0answers
32 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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13 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
34 views

Geolocation of L2G-Lite MODIS data

I would like to know if I am processing an L2G-Lite MODIS product, do I still need to geolocate, or reproject it to EPSG:4326? Or can I just leave it?
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1answer
46 views

GEE: Select random sample on known-NDVI-range for supervised classification

I intend to get random samples for training the supervised classification in Google earth engine. The code here, for example, I calculate NDVI and mask out NDVI < 0.65 (i.e. NDVI >= 0.65 is ...
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1answer
50 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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