All Questions
1,417 questions
0
votes
1
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GEE: hourly to daily evaporation ERA data
I'm trying to aggregate hourly data from ERA5 land to daily data over a specific shapefile in GEE. In theory my code is working, however, the output gives the same amount of evaporation for the entire ...
- 53
1
vote
0
answers
376
views
Extracting spectral signatures from ROI using ENVI5.3
I used ENVI's Band Math functionality for calculating a certain index to find out the dominance of a mineral. The output is one monochrome band as seen below, I really need your help to learn how to ...
user168625
1
vote
0
answers
1k
views
Modified Chlorophyll Absorption Ratio Index (MCARI) vs Green Chlorophyll Index (GCI) in a desert
I am using UAV multispectral data to compute different vegetation indices. Both of these indices were computed with the purpose of seeing/assessing the chlorophyll content, thus indicating if the ...
- 1,244
3
votes
0
answers
329
views
Alternative for Normalized Difference Built-up Index (NDBI) using satellite imagery with RGB & NIR bands
I am currently working with Planet SkySat multispectral imagery in Google Earth Engine (dataset description). It has only Red, Green, Blue and NIR bands. My objective is slum mapping and for this, ...
- 43
1
vote
0
answers
385
views
MSAVI vs NDVI for deserts
I calculated NDVI (Normalised Difference Vegetation Index) and MSAVI (Modified Soil Adjusted Vegetation Index) for a desert environment, where most of the vegetation is shrubs with some trees using ...
- 1,244
0
votes
1
answer
784
views
Converting Aster L1T data radiance to surface reflectance in Google Earth Engine
I'm working with Aster data in GEE and it's necessary to convert radiance in surface Reflectance values. I've tried to convert DN to TOA values, like this. It works. But I'm a little confused about ...
1
vote
1
answer
786
views
Why does Landsat 8 Collection 2 Band 10 data has spots with no values?
We're currently researching urban heat distributions in Germany using Landsat 8 data.
As stated in the Collection 2 Level 2 Science Product Guide, Band 10 of this product is the processed data of ...
- 13
0
votes
1
answer
151
views
Strange phenomenon in remote sensing index NDWI
I'm mapping water bodies in my region with Sentinel 2A Level 2-A imagery. I used ArcGIS Pro Raster Calculator to take (Band 3 - Band 8) / (Band 3 + Band 8) to get Normalized Difference Water Index. ...
- 246
1
vote
0
answers
337
views
Haze correction of Planet SkySat Public Ortho Imagery, RGB
I am using image - https://developers.google.com/earth-engine/datasets/catalog/SKYSAT_GEN-A_PUBLIC_ORTHO_RGB for slum quantification purpose but the problem is - the image seem to have haze as image ...
- 43
2
votes
1
answer
542
views
Spectral angle mapping from reference spectra in QGIS
I am trying to classify an ASTER image based on VNIR and SWIR reflectance of various rock types. I have standard reflection data for each rock type from the USGS spectral library and want to preform a ...
- 41
5
votes
0
answers
2k
views
Cropland field delineation using OpenCV and Google Earth Engine
I want to follow the methodology in the following article in order to find field boundary delineation automatically: "Multi-Temporal Crop Type and Field Boundary Classification with Google Earth ...
3
votes
0
answers
44
views
Empirical Line Method (ELM) in ArcGIS Pro [closed]
My images from 2017, 2018, 2019 and 2020 from the same area, recorded in the same time of the year, all look different regarding colour brightness, likely caused by atmospheric circumstances. As I ...
- 41
2
votes
1
answer
542
views
GEE: projection error when exporting data to a table
I am trying to export some vegetation condition index data calculated from MODIS data on Google Earth Engine to a table, but keep getting the error:
Error in map(ID=3): Image.reduceRegions: Unable to ...
- 861
2
votes
0
answers
65
views
Extract lines of rice terraces from satellite image
I have a Pleiades image and multiple rice field boundaries in a shape file.
What I want to do is for every feature in the shape file, clip the Pleiades image and detect the lines of the field terraces....
1
vote
0
answers
88
views
Indices similar to EVI for vegetation health analysis using UAV multispectral data
I know NDVI is the most commonly used index to start with vegetation health analysis. I am looking for other indices that can be calculated when the available UAV imagery has NIR, Red, Red Edge, Blue ...
- 1,244
0
votes
1
answer
531
views
TRMM Values Conversion From Float to Integer in Google Earth Engine?
In the below code TRMM product values converted from float to integer type in Google Earth Engine. However after the conversion TRMM product just shows 0 and 1. How can I can do conversion without ...
4
votes
1
answer
906
views
What is the appropriate input scale factor for EVI?
I am trying to calculate the Enhanced Vegetation Index using Landsat surface reflectance data. The formula for EVI using standard constants is:
EVI = 2.5 * ((NIR – Red) / (NIR + 6 * Red – 7.5 * Blue + ...
- 900
0
votes
1
answer
564
views
Conversion of UAV DN values to reflectance
My aim is to carry out fusion between Sentinel 2 and UAV images. Sentinel images are already converted to reflectance values but UAV images are in DN number format. How can I convert UAV DN values to ...
1
vote
1
answer
209
views
Is it possible to display a gray color GeoTIFF in ERDAS as it simply occurs in QGIS?
I have several GeoTIFFs (gray color) to be imported in ERDAS, however after googleing I could not find a way to display that color gradient as it occurs in QGIS.
Below the GeoTIFF displayed in QGIS:
...
- 2,131
0
votes
0
answers
127
views
Planet SkySat - Differences between image strips
I'm trying to understand why i'm seeing variations in the analytic (surface reflectance) imagery brightness values in Planet SkySat imagery between image strips that were collected around the same ...
- 1,314
3
votes
3
answers
2k
views
Issue with scaling factors for Landsat Collection 2 Level 2 data when calculating NDVI
I'm trying to calculate the NDVI for a scene, and I've downloaded Landsat 8 OLI/TIRS Collection 2 Level 2 data, which means it has already been processed to surface reflectance.
The scaling factors ...
- 31
2
votes
1
answer
386
views
Intake-STAC: KeyError: 'open_stac_item_collection'
I downloaded the AWS Earth search notebook from the intake-stac examples and whithout changing anything. Just run the cells...
But I've got everytime the error: KeyError: 'open_stac_item_collection'
...
- 163
2
votes
0
answers
118
views
Do PNG files suffer performance for scaled read over ERDAS Imagine (.img) files?
So I have a 20 GB in size Raster Image in .img format. Though I will be examining the code, to find out why, I am AMAZED at how quickly QGIS renders the entire file in a scaled format, and prior to ...
- 21
0
votes
0
answers
702
views
Process large ROI in GEE
I am calculating the VCI for Europe, but the ROI is too large for a single run in GEE. How can I divide it and process it in chunks so that when downloaded they fit into a single image/composite?
var ...
- 105
1
vote
1
answer
418
views
Mapping paddy rice fields with PMI(Paddy rice mapping index) with Google Earth Engine
I would like to perform mapping paddy rice with the Google Earth Engine for large scale. I came across with an article which proposed method for mapping paddy rice with special index related to ...
1
vote
2
answers
72
views
Extracting shorelines from BW aerial photos using ArcMap
I'm currently trying to analyze rates of shoreline change for an estuarine reserve by extracting & vectorizing shorelines from historic aerial photos, and then comparing those to the modern ...
- 75
0
votes
2
answers
2k
views
Set axis in Google Earth Engine Chart
I'd like to compare LAI (Leaf Area Index) data from the same region over different times using ui.Chart.image.series in Google Earth Engine.
I'm trying to set the axis to the same range, in order to ...
- 1
1
vote
0
answers
252
views
Removing cast shadow from Landsat 8
I've got Collection 2, level 2 Landsat 8 dataset which contain mountains. The problem is the cast shadows from the mountains, so that I can't classify these pixels well. These pixels have much lower ...
- 21
1
vote
1
answer
731
views
Filter by bound on Google Earth Engine not covering the whole of bound feature
I tried to filter Sentinel-2 image collection by bound, then I visualized the first in the collection after clipping to the bound feature.
The problem is that the returned images does not cover the ...
- 528
4
votes
4
answers
4k
views
What is lost when converting 12 bit imagery to 8 bit?
SPOT 6/7 satellite imagery is captured with a dynamic range of 12 bits per pixel per channel (ref). However almost all of the SPOT imagery I have seen in use has been 8 bits per channel, and split ...
- 28.3k
0
votes
1
answer
273
views
Need pros and cons of performing a GeoTIFF from ERDAS img conversion
I have a 20GB ERDAS IMG file that I need to incorporate into my project.
It's data covers the entire USA, indicating the thickness of satellite sensed tree canopy.
What image format would provide me ...
1
vote
1
answer
2k
views
Resampling Sentinel-2 ImageCollection on GEE having the bands with the same spatial resolution
I'm a beginner at Google Earth Engine.
I've seen on previous topics that resampling can be made on single images, like in this topic on downscaling raster images. I have an ImageCollection of Sentinel-...
0
votes
0
answers
28
views
Satellite image is cut when composite tool is run on it using ArcGIS Desktop [closed]
I am using satellite imagery in my project. The images come in squares, after using composite to join the bands, one square shrinks or is clipped somehow.
Does anyone know the solution?
See the ...
- 11
1
vote
2
answers
1k
views
How can I have the ground sampling distance from the images?
I have some aerial images and I need to know how if I can have the ground sampling distance value from the image without calculate it from the plane fly's parameters.
0
votes
1
answer
322
views
Google Earth Engine: memory error when calculating monthly average precipitation for a small region using GLDAS data
I am trying to calculate the total monthly precipitation rate using the Rainf_f_tavg band of the GLDAS-2.1 image collection on Google Earth Engine (https://developers.google.com/earth-engine/datasets/...
- 861
1
vote
1
answer
486
views
Tried to Mosaic Sentinel 2 images but my final image appeared with some overlapping Null data
I'm working on an area that required me to use three sentinel images to fully cover it, I used the "mosaic to new raster" tool in ArcGIS to merge the three images and was surprised to find ...
4
votes
1
answer
2k
views
How to loop through each feature in a shapefile in Google Earth Engine?
I have written a script which calculates the mean NDVI, NDWI, and NDDI (Normalized Difference Drought Index) values for a given county in a specified time period. These values are then outputted to a ...
- 41
3
votes
1
answer
617
views
How to remove banding in Sentinel-2 imagery over water?
In several L2A Sentinel-2 images, I've seen an angular banding effect over water bodies. Another user thought that these seam effects were caused by aerosol scattering affecting each of the S2 MSI ...
- 273
-1
votes
1
answer
161
views
Google Earth Engine - error in function to plot seasonal vegetation index for a region using MODIS data
I am trying to create a function to calculate the average Vegetation Condition Index
((mean NDVI of individual year)-(min NDVI from full period)) / ((max NDVI from full period) - (min NDVI from full ...
- 861
2
votes
1
answer
309
views
Remote sensing product's raster extent not agreeing with specified projection in R
I want to plot remote sensed sea ice concentration data for Antarctica, in Program R. The product website (http://cersat.ifremer.fr/data/products/catalogue) says the data are in Antarctic polar ...
- 25
1
vote
0
answers
132
views
GEE NDVI time series extraction does not populate CSV file columns
I am trying to extract a time series of sentinel NDVI data. This script (below) takes a feature collection of points, buffers around them, and collects all available imagery 30 days before each ...
- 425
0
votes
1
answer
491
views
What is name of dataset in GEE to estimate level of urbanization for each county (district) in a country /region?
I am epidemiologist, not remote sensing expert. I am interested to find association between disease incidence /reported cases with urbanization (hypothesis " more bigger cities , more incidence&...
- 105
0
votes
0
answers
1k
views
Google Earth Engine goes unresponsive during large extraction
What we are trying to do:
We are trying to extract a NDVI time series for a large dataset of insect outbreaks. This time series needs to be associated with the observation date for each insect ...
- 425
2
votes
1
answer
494
views
Exporting EVI image on Google Earth Engine with visual parameters between -1 and 1?
I am having an issue with exporting an EVI image with the visual parameters between -1 and 1. On Google Earth Engine (GEE), using the inspector tool, the values are between -1 and 1, but when I export ...
- 21
1
vote
0
answers
46
views
Putting a point over pixels with highest DN values within grids in QGIS [duplicate]
I have a raster layer in greyscale, and a vector layer that is 3 x 3 m grid. One of the attributes within the grid cell layer is the value of the highest DN number within that grid cell. I just need ...
- 207
-1
votes
1
answer
2k
views
Applying Otsu thresholding method to raster in QGIS
How can I apply Otsu’s threshold method to a Raster in QGIS for reduction of a gray level image to a binary image?
- 537
1
vote
1
answer
653
views
What is the difference between InSAR and PolSAR? [closed]
How to define those two SAR Technologies?
- 19
5
votes
2
answers
5k
views
Computing Excess Green Vegetation Index (ExG) in QGIS [duplicate]
I have to process the image for Sugarcane row detection and extraction.
Sample image is accessible from the link: https://github.com/AndresHerrera/croprows_generator_pa_v2/tree/master/droneimages
I ...
- 537
2
votes
1
answer
147
views
Designing a Low Pass Filter
How can I design a similar Low Pass Filter as given below which takes into account only 4-connectivity and ignores the pixels that complete 8-connectivity?
- 151
3
votes
2
answers
672
views
Is Satellite Image Continuous Data?
I have a satellite image of one region. I perform interpolation on this image. However, I am not sure Satellite Image is continuous or discrete data.
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