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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Interpreting NDVI value on water?

There is a surreal thing on my NDVI images. NDVI values on lake is ranging from -0.04 to 0.7. (The lake surrounded by forest and has freshwater). Theoretically, negative value of NDVI is correspond to ...
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398 views

ENVISAT ASAR .N1 file is not being opened by ERDAS IMAGINE 2011

I am not able to open ENVISAT ASAR .N1 file in ERDAS IMAGINE 2011. The software has direct read option for files of this format. Whenever I try to open the file, software closes automatically giving ...
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0answers
2k views

Principal Component Analysis in QGIS

How do I go about to perform a band ratio and Principal Component analysis in QGIS? I need to derive principal components from ratios of landsat TM bands .
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1answer
838 views

Accuracy assessment in Erdas imagine

Is it necessary to do an accuracy assessment for an unsupervised classification done for a Landsat 5 image?
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1answer
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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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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9 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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18 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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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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45 views

KeyError: 'BANDS' and NameError: 'bands'

I am trying to follow this tutorial: land cover fastai And while executing the workflow, I got this error: eopatch 0 has been processed! ---------------------------------------------------------------...
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35 views

Correcting offset between LiDAR datasets

I am analyzing multiple LiDAR datasets looking at the changes between pre-wildfire and post-wildfire topography. The datatsets are of the same general location. I did not acquire the datasets on my ...
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28 views

Nearest Neighbor Global matching

I'm trying to compare two datasets; a satellite image and some known points. In the satellite image I've got 20 to 50 detections that should match up to a set of lat/lon points that I have. There is ...
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27 views

Proper formula for computing signal-to-noise ratio of a camera?

I have a 5-band muultispectral camera, and I'm trying to find the signal-to-noise ratio (SNR) to supplement some research data I collected. Cameras with low SNRs generally have lower-quality images ...
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107 views

PlanetScope NDWI calculations

I am trying to calculate NDWI for a PlanetScope image scene. I currently have 2 products: one is the "3B_AnalyticMS_SR.tif" and the other is the "3B_AnalyticMS.tif" product. I believe the former is ...
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44 views

Why am I unable to create overviews in QGIS despite having disk space

I have 120 GeoTIFF files, totalling around 250GB of data. Files names are from 1.tif to 120.tif. I tried to create overviews for all the files in one go usinggdaladdo in terminal. While overviews ...
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30 views

The emissivity of snow

I try to use the NDVI Based Emissivity Method to calculate the LSE. But the function almost applied over surfaces composed by soil and vegetation. Over surfaces like water, ice, or snow did not ...
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33 views

Whether NOAA AVHRR NDVI V5 already remove cloud?

We want to use NOAA/CDR/AVHRR/NDVI/V5 datasets for analysis, but we are not sure if the NDVI already remove the cloud and cloud shadow or not? Need we use 'QA' to remove the cloud and cloud shadow ...
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63 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 ...
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40 views

Why does a raster that consists of 3 bands appear greyed out?

I have a raster that is formed by stacking the bands blue, green and red of "Landsat 8", when it is displayed on Erdas Imagine 2015 it appears as if there is a semi-transparent grey layer over it, the ...
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9 views

TIMESAT3.3 output errors

When I ran "fit2img" in TIMESAT3.3,I got problematic result image.Contrasted with original image, this result image seemed to be cut into two parts and was badly deformed.I did not know what happened....
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1answer
45 views

Conversion of MLS/AURA RELATIVE HUMIDITY PRODUCT to correctly referenced GeoTIFF

I have downloaded the following product https://cmr.earthdata.nasa.gov/search/concepts/C1251101764-GES_DISC.html and it gives me a .he5file. Can anyone help me in correctly geo-referencing the file ...
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2answers
506 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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100 views

Clip a Mask (NDSI) from another Mask (NDWI) in GEE

I have created a mask of Normalized difference Snow Index (NDSI) in the late winter using a combination of Landsat 5,7,8 imagery and I would like to only keep a remaining land features by clipping out ...
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94 views

Automatically Recognised Targets for Combined Laser Scanning and Photogrammetry

I'm currently performing an engineering honours thesis on terrestrial photogrammetry and laser scanning in Archaeology. Both methods will be used to document a single location first and analysis will ...
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46 views

How to Substract one image band from the subsequent in Google Earth Engine?

i am trying to find the day of year (doy) for each year with the highest change in NDVI compared to the day before, to map in the end a shift in start of season. My code to seperate each year so far (...
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50 views

Orfeo rescale problem?

I have downloaded a Sentinel image, what I histogram matched first with the following Orfeo codes (a cut the low and high 2 percentiles): # Import the otb applications package import otbApplication # ...
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0answers
174 views

Topographic correction in QGIS SAGA error: Input layers do not have the same grid extent

I have sentinel-2 layer images and one TIN image. I resampled the TIN to same spatial resolution in Layer 4 (10m). Both images are in the same reference system. But when I try to perform topographic ...
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0answers
140 views

Transect profile plot matlab

I have 3D matrix file where XYZ are lon,lat and height. I plot these XYZ value using scatter3. Now I want to plot profile of height (along a line in km) of the data where xaxis:distance along line in ...
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59 views

Using result raster of Semi-automatic classification to obtain spatial statistics?

I finished classification (use SACP in QGIS), and got a classificated raster. Now I want to obtain characteristics such as sum area of class, areas of different polygons separately, etc. I tried use ...
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0answers
56 views

Loading MOPITT data into QGIS?

I have a problem importing Terra MOPITT data into QGIS (2.18) correctly. The data is in hdf5(HDFEOS) format. QGIS/GDAL imports the data, but the image is rotated by 90° and shifted. QGIS error: CRS ...
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0answers
109 views

Can NIR minus Red be used instead of NDVI with Drone Imagery

I have some CIR imagery collected by a vendor using a Cannon Powershot S110 NIR, from an eBee fixed wing platform, about 400 ft AGL. All images were stitched together by the vendor in Pix4D. I want to ...
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0answers
89 views

Endmember selection when applying SAM, SVM and MLC to PCA

I intend to apply the Spectral Angle Mapper (SAM), Maximum Likelihood (MLC) and Support Vector Machine (SVM) algorithms on a hyperspectral dataset in ENVI but I am slightly confused as to how to ...
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0answers
308 views

How to perform accuracy assessment in eCognition?

I have already done the classification using Nearest neighbourhood, and how do I continue to complete AC with TAA?
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32 views

Analyzing large rasters from an image service

I'm working with NAIP imagery in ArcGIS 10.4.1 that I'm accessing through the USDA server (https://gis.apfo.usda.gov/arcgis/services). I want to perform focal statistics on bands 2 and 4 (green and ...
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0answers
48 views

What is the best way NDVI can be used for assessment of remediation level of ecosystem (after nuclear accident)?

I am thinking about ways to assess efficiency of various bioremediation methodologies and self-remediation of an ecosystem polluted with nuclear waste. I would like to use NDVI as an assessment ...
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0answers
125 views

Software for matching spectral end members with spectral library

I am working with Moon Mineralogy mapper(M3) - hyper-spectral data and i am trying to match the endmembers obtained from M3 with RELAB spectral library. I have tried spectral analyst tool in ENVI but ...
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0answers
69 views

Vector Layer not displayed properly in 3D

I am using Qgis2threejs plugin to display my map in 3D. But I am facing a problem in displaying vector layer properly. Please look at the following image.Buildings are not displayed according to DEM. ...
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0answers
53 views

SPOT 6 parameters to open data in matlab

I'm trying to open SPOT 6 data on Matlab using multibandread, but since I don't have some of the paremeters I'm only getting a black image. I've been looking on the web for these parameters but I ...
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0answers
207 views

Sieve in QGIS returns unexpected results

I have a rasterimage with values between 1 and 5. I want to sieve it, using QGIS - Raster - Analysis - Sieve. But then I get this: The values changed. Even worse, when I color it, the whole raster ...
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0answers
30 views

What indices could is use for coastline extraction using rapideye imagery

I am currently writing a proposal to get RapidEye imagery for my master thesis. In this proposal I am trying to explain what I am doing. Except NDVI/NDVI-RedEdge and NDWI, can anyone suggest some ...
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0answers
79 views

Spectral classification for crops

I'd like to do a classification using a multispectral raster (1 Blue 475, 2 Green 560, 3 Red 668, 4 Red Edge 717, 5 Near IR 840). I'd like to classify the crops (kiwi plants). I tried a few ...
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211 views

Why are Landsat-8 derived NDVI values higher than SAVI values?

I have calculated NDVI and SAVI vegetation indices for a landsat-8 image. I am unexpectedly getting higher values for the NDVI than SAVI. What may be causing these unusual results? NDVI=0.46 SAVI=0....
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70 views

How to make LISS-III image coloured

In order to study land use and land cover change from LISS-III images I want to see the image coloured (i.e. false-colour composite RGB) using ENVI 5.0. What is the procedure?
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188 views

Difference between radiometric correction at surface and at sensor in ENVI

I want to ask you about the difference between the radiometric correction at surface and at sensor in ENVI software, I do the two in flash and radiometric correction and the results was same image. ...
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69 views

GRASS: strange classification output and reject map from “i.maxlik”

I am trying to perform a supervised classification with "i.maxlik". I have three bands: 1) elevation (a dem); 2) reflectance (derived from Landsat ETM+ band4); 3) cumulative solar radiation (derived ...
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0answers
63 views

qgis Semi automatic classification pluggin how to add text to rows in attribute table

I want to use a previously created shapefile as Training shapefile in the semi automatic cassification pluggin. Therefore i added 4 fields to this shapefile: Macro_ID (int), MCl_info (text), Class_ID (...
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75 views

How to extact very narrow water linear features from GeoEye-1 image

I need to extract beaver channels from a GeoEye image (attached image). What is the best approach to automatically delineate such very narrow and not very sharp water features?
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0answers
143 views

Hard wood tree and Soft wood(shrubs) Vegetation Differentiaton

How I Differentiate Hard wood tree (like Mango, Sal) and Soft wood(shrubs like reed) Vegetation using Multispectral or Hyperspectral Image? I have TM, ETM, OLI, Hyperion, Aster Image and ERDAS 2011, ...
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0answers
258 views

Enhancing/smoothing Landsat 8 image using ArcGIS Online?

I understand that Landsat 8 is 30m resolution, but is there any technique that can be used to smooth/enhance the NDVI or Agriculture Landsat layers in an ArcGIS Online (AGOL) web map? I have adjusted ...
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0answers
196 views

What kind of raster mosaicking to use in land cover analysis

I have to mosaic two rasters (Landsat ETM+ scenes) to one single image and then analyse its land cover. Which option to use to avoid seeing a distinct line in the place where two different scenes/...