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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14
votes
3answers
8k views

Land Cover Feature Extraction from Satellite Imagery

I'm interested in a low-cost or open source solution for creating land cover GIS layers that utilize both spectral and textural extraction algorithms. I have used PCI Geomatica, ENVI, and Feature ...
18
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4answers
13k views

Free GIS software for orthorectification?

Could someone recommend a free and/or open source GIS application that can orthorectify map images?
12
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5answers
6k views

Extracting tree crown areas from remote sensing data (visual images and LiDAR)

I am looking for a method to process a remote sensing image and extract the crown areas of the individual trees from the image. I have both visual wavelength areal imagery, and lidar data from the ...
27
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6answers
14k views

What is Change Detection and how I can perform such analysis with open source tools?

From wikipedia page: Change detection for GIS (geographical information systems) is a process that measures how the attributes of a particular area have changed between two or more time periods. ...
25
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12answers
20k views

Seeking open source software package for Remote Sensing?

Here are many questions with great answers about open source GIS software. I am wondering, what is the best open source software package for Remote Sensing? I would like to learn it and to use in my ...
13
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2answers
14k views

What are LiDAR returns?

Can someone help with an explanation and some references, in order to understand the nature of return pulses within a LiDAR system.
14
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2answers
9k views

How to fill gaps in SLC-Off Landsat 7 ETM+ Images with QGIS?

Explanation of the problem: On 31 May 2003 the Landsat 7 Enhanced Thematic Mapper (ETM+) sensor had a failure of the Scan Line Corrector (SLC). Since that time all Landsat ETM+ images have had ...
6
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2answers
3k views

Open source solutions for Landsat-8 mosaicing and correction?

I am familiar with the major commercial remote sensing packages (ENVI, IDRISI ERDAS, etc), but I haven't previously had the opportunity to utilize open-source solutions. I have a several new Landsat-...
5
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1answer
5k views

Open Source Alternatives to ERDAS IMAGINE ATCOR?

I have been using ERDAS IMAGINE's ATCOR extension for ATmospheric CORrection of ASTER imagery. What opensource options exist for atmospheric correction of ASTER Level 1B products? I'm primarily ...
7
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1answer
6k views

Reprojected MODIS NDVI has range from -32768 to 32767, expected -1 to 1

I'm new to StackExchange and to remote sensing. I am working with MOD13Q1 250m 16-day MVCs. My goal is to use NDVI time-series to classify cropping pattern and crop type, then link this data to ...
2
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1answer
478 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. ...
37
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7answers
8k views

Machine Learning Algorithms for Land Cover Classification

I am interested in learning what software exists for land classification using machine learning algorithms (e.g. k-NN, Random Forest, decision trees, etc.) I am aware of the randomForest package in R ...
17
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3answers
4k views

Is there a way to automate the preprocessing of LANDSAT data?

I'm currently enrolled in a remotesensing course, using LANDSAT data. Part of my course is about standardizing the scenes based on radiance values. I assume that because this is such a tedious task, ...
14
votes
1answer
7k views

Difference Between Radiometric calibration and radiometric correction

I am new in remote sensing field. I sometimes got confused when I read about image pre-processing. Can someone please elaborate to me the difference and some example methods to do radiometric ...
3
votes
1answer
2k views

Is atmospheric correction necessary when working with multi-spectral indexes?

When you are working with Landsat Level 1 data and calculate indexes, e.g. NDVI, NDBI, SAVI ..., do you calculate them using raw data (pixel DN value), or atmospherically corrected data (surface ...
11
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3answers
1k views

Sentinel-2 satellite images not aligning properly

I'm downloading Sentinel-2 tiles from Amazon S3 but they dont seem to be 100 % aligned. Right image is band 08 Sentinel-2 added to ArcGis Desktop (i have done nothing more than adding the 08.jp2 to ...
6
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1answer
2k views

How can I parse modis MOD13Q1 quality layers in R?

I'd like to parse MOD13Q1 VI quality layers in R. My original code must have been incorrect, because it gave lots of "deep ocean" flags in the middle of Brazil. After the changes suggested by Mikkel,...
1
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2answers
2k views

Extracting land cover type in Google Earth Engine?

I have a question related to Drawing polygon and extracting land cover inside using Google Earth Engine? I'm trying to work out how to calculate habitat type area from within a specific polygon in ...
4
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3answers
1k views

Download MODIS/MCD19A2 AOD product with R

I'm looking for a programmatic way to download MODIS/MCD19A2 AOD data in R. So far, I've found a pretty solid R package called MODISTools that works nicely with the MODIS/VIIRS RESTful API. However, ...
18
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9answers
7k views

Which Tools do you use for Classification of Remote Sensing Data?

Which tool do you prefer to use for classification of remote sensing data, e.g. classifying land use, and why? Which other tools have you tried, and why did you decide against them?
11
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2answers
2k views

Extracting roads out of Landsat raster images

For a study into the expansion of road networks in the rainforest I am trying to extract roads out of Landsat images. We already have sharp and cloud-free composites on which the roads are clearly ...
11
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2answers
3k views

Finding Sentinel tile for specific Long/Lat coordinate

I'm building a tool that downloads images from "Sentinel-2 on AWS" I have a trouble translating Long/Lat coordinates to a specific Sentinel tile. I know that Sentinel 2 uses MGRS and I tried to ...
10
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2answers
473 views

Why Landsat ETM+ panchromatic band' wavelength steps over visible range?

The Landsat ETM+ band-8 (Panchromatic) is identical to Landsat-8 OLI' Panchromatic band-8 in terms of spatial resolution i.e. 15 x 15m cell size. However, there is great difference in the wavelengths ...
8
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2answers
16k views

image segmentation of RGB image by K means clustering in python

I want to segment RGB images for land cover using k means clustering in such a fashion that the different regions of the image are marked by different colors and if possible boundaries are created ...
7
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1answer
2k views

Calculating EVI from Sentinel 2 imagery gives difference in results between ArcMap & QGIS?

Though EVI coefficients have not been developed for Sentinel 2 imagery, I am using the same coefficients used for MODIS to calculate EVI for Sentinel imagery. I know that Sentinel 2 imagery is TOA ...
4
votes
1answer
668 views

Statistical analyses for survey against raster?

I am somewhat of a newbie to geostatistical analyses, but pretty familiar with GIS and remote sensing packages. I was wondering if anyone had suggestions on appropriate geostatistical analyses for a ...
9
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2answers
339 views

Identifying Joshua trees with LiDAR data?

I'm working on a LiDAR project to determine where Joshua trees are located within a specified study area. Due to the vegetation cover being so sparse, there are really on 2 canopy species there, which ...
2
votes
1answer
256 views

Incorporating terrain data to predict canopy cover using randomForest in R? [closed]

I have a 5.8 m resolution satellite image (LISS IV by IRS-P6, in bands 4, 3 and 2) of a densely forested region in the Eastern Himalayas (altitude 700 m to 3200 m). My objective is to predict regions ...
5
votes
2answers
863 views

Why does the resolution decrease with increasing incidence angle in the Sentinel-1 SAR sattelite

On this link (Sentinel1 webpage for a SLC product), the resolution is written as a range from the highest corresponding to low incidence angle, to the lowest resolution corresponding to high incidence ...
5
votes
7answers
9k views

Failed to create signature file

I've no clue how to solve this issue in the exercise that I'm trying to perform. The point where I'm stuck is 4. "Create signature file as LandsatCompS.sgs". I've done what it says in the exercise. I ...
3
votes
2answers
517 views

Is SRTM 3 second arc free of non-terrain features?

I made an elevation map of my study area in Macapa, Brazil. But the region has the average elevation lesser than 30 m as I can see from my map derived from SRTM 3 second arc. According to my ...
3
votes
1answer
2k views

How to Normalize or rescale the NDVI raster image

I have processed my landsat band 3 and band 4 of different years to derive NDVI values the possible values of Normalized difference vegetation index is -1.0 to +1.0. The bands were atmospherically ...
3
votes
2answers
3k views

How to perform an accuracy assessment in eCognition?

How to do accuracy assessment of classified images in ecognition? I have done the image segmentation for Worldview-2 image. Then, I have processed for classification for class names (e.g road,...
2
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1answer
2k views

How to to extract coordinates of pixels inside a polygon in Google Earth Engine as a single feature? [duplicate]

IMPORTS: var geometry = /* color: #d63000 */ee.Geometry.Polygon( [[[-67.76435852050781, -22.213792811479802], [-67.76641845703125, -22.220785143658368], [-67.75646209716797, -22....
2
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1answer
3k views

Tutorial Vegetation Condition Index

Anybody here can help me regarding calculating Vegetation Condition Index (Kogan,2004) for Landsat?. Specially facing problem in NDVI_max and NDVI_min; which should be maximum and minimum value?
1
vote
1answer
460 views

Generating a DEM and DSM from correct LiDAR point classification

I have downloaded classified LAS data from http://lidar.unh.edu/map/ I am trying to generate accurate DEM and DSM for further analysis. I created a LAS dataset with a projected CRS of ...
0
votes
1answer
469 views

What are the necessary correction/calibration on Landsat 8 imagery for land cover classification? [duplicate]

I downloaded calibrated/corrected Landsat 8 data (Level 2) from ESPA (https://espa.cr.usgs.gov/) to do land cover classification. But there are many corrections and calibrations can be done as listed ...
4
votes
1answer
1k views

Orthogonal correction of building footprints after extracted from a raster

I have ArcGIS 10.1 and am working on a project involving extraction of vegetation and building classes from LIDAR (unclassified) data and aerial imagery (resolution 30x30cm). I have managed to ...
3
votes
2answers
4k views

Converting *.tif file into headerless (flat) binary file?

I am using NDVI files (value range -1 to +1) created from Landsat CDR images to produce a timeseries in TIMESAT software. My .tif file has following characteristics. File type TIFF,Data Type ...
1
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2answers
1k views

LANDSAT 8 i.landsat.toar error GRASS 7

I am a bit new to GRASS, but I have managed to get a lot of good work done thus far. However, the following error is really throwing me off, because I can't find any help anywhere for it. I am using ...
1
vote
1answer
481 views

How to select all points of a polygon in google earth engine as a single feature?

IMPORTS: var geometry = /* color: #d63000 */ee.Geometry.Polygon( [[[-67.76435852050781, -22.213792811479802], [-67.76641845703125, -22.220785143658368], [-67.75646209716797, -22....
1
vote
2answers
1k views

How to find the minimum pixel value within a region of interest?

I am working on a Python script for dark object subtraction, a radiometric correction method for remotely sensed data.To accomplish this, I need to find the minimum band pixel value of a waterbody ...
0
votes
1answer
497 views

Unable to writeRaster for signature “rasterPCA”, “character”

I am currently trying to obtain two rasters that are the Principal component axes 1 and 2 for a list of bioclimatic variables that I am using. I am using the rasterPCA() function that exists in the ...
15
votes
3answers
1k views

Ecological geospatial conundrum

I am looking for a different, more elegant solution to a spatial statistics problem. Raw data consists of an x-y coordinate for each individual tree (i.e. converted to a point .shp file). Although ...
14
votes
5answers
8k views

Recommended programming language for remote sensing?

I am beginning studies that hopefully will lead to a long career as a remote sensing specialist. I am currently working with ArcGIS for some applications and learning ENVI for others. I have ...
12
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8answers
2k views

Is there a smartphone app for mobile asset logging?

I'm after a recommendation for a smartphone app (iPhone or Android) to log asset information for litter bins. I need the following features GPS geotagged photos Form with drop down menus for user ...
6
votes
2answers
5k views

Are there Python packages for Landsat 8 processing?

While there are a number of python projects for MODIS acquisition and processing (pyModis and get_modis), I have yet to encounter a toolset for automating Landsat 8 processing in Python. There's ...
17
votes
7answers
18k views

Source for high-resolution satellite images free/low-cost?

I am doing a household survey in Kenya, and I need to ensure that my survey team visits every house within a given area. I've been going to google maps and right-clicking on roofs to get coordinates ...
11
votes
1answer
2k views

Multispectral image segmentation for natural-resources applications using R

R has the capacity for image segmentation, although all of the examples I have come across utilize a single band for the segmentation (example). I am interested in combining R's capacity for random ...
18
votes
1answer
32k views

Panchromatic Image association with high spatial resolution

How and Why is a Panchromatic Satellite Image associated with high spatial resolution? I googled and found that it is a single band image, but then why is it called pan-chromatic(All Colors). Does it ...