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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0
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2answers
116 views

Satellites to retrieve UV bands

I want to retrieve some satellite images with UV bands,Bun I don't know which satellites are providing UV bands and We can freely download them? I have already downloaded Modis and Landsat images,But ...
1
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1answer
82 views

Is TOA reflectance in floating point or DN? [closed]

After converting at radiance to TOA reflectance,is going to be in DN or floating point.
0
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2answers
42 views

How to load two images in ENVI 5.1?

I am using ENVI 5.1 and when I use the Data Manager to load several images and if I want to load two adjacent images, why would one of them load and the other doesn't?. Am I missing something here ?
2
votes
1answer
773 views

How to create NDVI map From LiDAR intensity and RGB image

I am new with GIS and I've been looking for ways on how I could create a NDVI map from LiDAR intensity and RGB image. Is there any way I could do this? I have read that you could create an intensity ...
2
votes
3answers
109 views

Determining surface that reflectance curve matches?

I was wondering to what surface that reflectance curve belongs? It is definetely no water or snow since their reflectance drops at a much smaller wavelength. I was thinking about a dense cloud but ...
1
vote
1answer
73 views

TIMESAT Land cover class

Is it possible to monitor phenology of only 2 land cover classes in TIMESAT? Example is corn and wheat for 7 years. Sowing structure of this crops changes every year, i.e. their location on an image ...
1
vote
3answers
1k views

What is an inexpensive way to map underground Utilities, like pipes, gas lines and telephone lines

I just got hired on to a small local government i am sill learning the ropes as a GIS Analyst. What is an inexpensive way to map underground Utilities, like pipes, gas lines and telephone lines? What ...
0
votes
1answer
60 views

Classifying type of land use each spectral represents from remote sensed data?

How do you know the type of land use each spectral represents from an remote sensed data into a classification ? Which classification is the most typical to use when doing that ? How many ...
0
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1answer
47 views

How to create my own remote sensing index?

Using Landsat images how do I create my own indices to extract particular landuse? Are there any tool/ software for creating indices?
5
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1answer
276 views

Why does Landsat 8 panchromatic band NOT include the infrared?

The panchromatic band on Landsat 8 OLI sensor (band 8) covers a narrower portion of the spectrum than the corresponding band in Landsat 7 ETM+: 0.50 - 0.68 micrometers (L8 OLI) in contrast to 0.52 - ...
2
votes
1answer
76 views

Obtaining free satellite imagery for Australian floods?

How can I obtain free satellite imagery for Australia? I want to find the extend of flood in specific time. I have already tried land-sat.But unfortunately there is no data available for that specific ...
4
votes
2answers
392 views

Why use feature extraction?

Why is feature extraction important? Why do we have to reduce the feature space? Is it only a computational problem when we use hyperspectral imagery or does this procedure improve the ...
2
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2answers
129 views

Feature extraction in remote sensing! [closed]

Which are the most common features in order to perform a supervised classification in remote sensing? Furthermore anyone worked with SAR features? Which are the most commonly used? Can anybody suggest ...
1
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0answers
207 views

Retrieving Aerosol Optical Depth (AOT) from Landsat multispectral data

I need to retrieve Aerosol Optical Depth from Landsat multispectral datasets. Has anyone successfully tried something like that before?
4
votes
3answers
1k views

Pixel-based and object-based classification!

I would like to understand if pixel-based classification algorithm (e.g. Maximum Likelihood classification ) can be used for object-based classification (i.e. after a segmentation procedure). On the ...
7
votes
2answers
1k views

what's the difference between spectral signature and features in remote sensing?

I would like to understand if is there any difference or relation between spectral signature concept and features in remote sensing?
0
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2answers
122 views

How convert a Modis hdf to txt with lat long using a command line

I need convert, from command line, an Modis hdf file to txt with lat/long extracting EVI. Thanks
2
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0answers
440 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 ...
1
vote
1answer
1k views

Masking clouds with Fmask

I have been trying to mask clouds with the quality control band with landsat 8 imagery. The problem I continue to run into is that the quality control bands mistake tops of buildings and concrete as ...
2
votes
1answer
442 views

Python script for dark object subtraction on Landsat 8 Imagery

Does anyone know of any python scripts that will allow me to conduct such a process? I am limited to open source software and have minor experience in Python.
1
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0answers
13 views

How to avoid background zero values in erdas imagine model maker? [duplicate]

Does anyone know how to avoid background black color/ zero value in background pixels in processed images using erdas imagine? Particularly in model maker. It's confusing in statistical calculation.
2
votes
1answer
485 views

Workflow of Processing Landsat data for landcover classification

I have downloaded Landsat-8 data to make a land-use raster. So far I've made a composite image and clipped it by my study area. As you can see, there is some slight cloud cover. I've gone ahead and ...
5
votes
0answers
598 views

QGIS 2.4.0-Chugiak: How to threshold NDVI to calculate emissivity for land surface temperature

I am analysing urban heat island using thermal band 6 of landsat TM-5 sensor with respect to Normalized difference vegetation index that derived from the Band 3(Red) and Band 4(NIR). Lansat TM years ...
3
votes
0answers
436 views

Single Tree detection

I was wondering how I could extract "crown area" of single trees in a forest from a high-resolution image with only 3 band (RGB) in ArcMap. ( No NIR to use NDVI as any threshold). I need a fast ...
8
votes
3answers
568 views

Handling mountain shadows when classifying Landsat 8

I'm trying to classify some area in northern Mongolia using Landsat 8 satellite images from 2013. Since the recordings were made in winter, the sun is very low at the acquisition time. Therefore there ...
2
votes
1answer
82 views

Determine mudflats area from remote sensing images

I need to determine the mudflat area for a group of small islands in the Red Sea. I have read some publications and it seems to be possible using remote sensing, for example Landsat. But I am not ...
19
votes
3answers
4k views

How to produce high-resolution DEMs from new Sentinel-1 data?

This is a general question relating to the new Sentinel-1 data. I'm interested in the potential for using this data to create high resolution DEMs in GIS (I use QGIS), to investigate archaeological ...
2
votes
2answers
230 views

How to derive the slope angle value from DEM?

I am trying to calculate the steepness of each pixels (30m) from the DEM of 2m resolution. I have made use of ERDAS Imagine - Slope function and returns a contour-like pixel image. The pixel value ...
7
votes
2answers
13k views

Download new SRTM 30 meters

I read about the new version of the digital elevation model at 30 meters (SRTM 30 meters), but I can not find from were I can download it. some sources: ...
2
votes
2answers
813 views

automatically geo- and ortho- rectify raw Landsat data using DEM

I have a dataset of 20 Landsat scenes (MSS, TM, ETM+) for 20 years (one scene per year). Scenes are in WGS 84, EPSG 32634 coordinate system and I can easily project = geometrically correct them to ...
3
votes
2answers
896 views

Cloud/Shadow Masking: How to shift a cloud mask in Erdas/ArcMap/Py Script

I have the task to mask out cloud cover in approximately 20 landsat 8 scenes. Creating the cloud mask for the "white part" is easy, but I need help in addressing the clouds shadow. General ...
2
votes
1answer
400 views

Possible to use same signature file to classify images from different years?

I have Landsat images for the same area over 20 years (one photo per year in same season). I would like to detect changes occured in forested area like clear-cut and bark beetle outbreak over time. I ...
1
vote
1answer
467 views

QUAC atmospheric correction for Landsat-8 (ENVI 5.0)

I try to realize QUAC atmospheric correction for the band 4 and band 5 of Landsat-8 in ENVI5.0. This version doesn’t support Landsat8 (doesn’t have parameters of Landsat-8). At the first step I glued ...
2
votes
0answers
48 views

A problem about Correlated-K algorithm of MODTRAN 5

When I use MODTRAN 5.2.2 to run the test case 'CorrelatedK.tp5', I get the following warning information. How I can solve this issue? WARNING: The Correlated-k option was turned off. The ...
5
votes
2answers
257 views

How to filter LiDAR data by scan angle?

I am looking to filter LiDAR data (.las format) by scan angle specifications (e.g. keep all points < 15). From a basic Google search, it appears that the LibLAS library has the ability to filter by ...
3
votes
2answers
966 views

Calculating NDVI using Landsat ETM+ band values

I have sample points (shape file converted from a .xls file which contains XY coordinates,nnx,nny and canopy density) and a landsat etm+ image. First I applied 'SpatialAnalyst Tools>Extraction ...
1
vote
1answer
219 views

Maintaining spatial integrity of Matlab matrix with missing data

I am working with MODIS Terra imagery (MOD13Q1). I am currently trying to compute the autocorrelation structure of the pixels in an MODIS NDVI raster. The problem is that I have clipped the original ...
1
vote
1answer
54 views

how to perform PCA with 2 different landsat scene

I want to perform PCA on 2 sheets of Landsat imagery with different acquisition time and coordinates. prior to processing, should I combine both into one scene (mosaicking process)? if so, how is the ...
4
votes
1answer
152 views

Low top of canopy surface reflectance values

I have calculated at sensor reflectance for a multispectral image and performed atmospheric correction. The reflectance values for the visible and NIR bands are between 0.2 to 0.01 for surfaces, ...
2
votes
1answer
457 views

Spot 6 - Reflectance calibration

I have a Spot-6 image and the metadata contain 9 values of SUN_ELEVATION (BottomRight BottomCenter BottomLeft CenterRight Center CenterLeft TopRight TopCenter TopLeft). I've used before Landsat and ...
6
votes
3answers
602 views

How to generalize training data for a random forest classifier?

I am working with a random forest classifier in eCognition (new with eCognition 9.0). The image shows 8 NAIP tiles I am attempting to classify using approximately 100 training points. The training ...
5
votes
3answers
63 views

Residential tree cover for surveying?

Can someone point me in the direction of some high spatial resolution and reasonably recent satellite imagery for central Canada (Manitoba)? I am trying to determine whether I can generate accurate ...
7
votes
1answer
5k 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 ...
2
votes
0answers
75 views

How to detect temporal changes using ArcGIS? [closed]

I want to show urban sprawl in a city over ten year period. I took a MOOC on geospatial revolution, therein a link was shared to do such analysis. I just want to show the urban sprawl, nothing ...
1
vote
1answer
972 views

How to display the one band layer in pseudocolor using ERDAS Imagine?

I am a new user in ERDAS imagine and i found it hard to turn the single band raster data from grey color to pseudocolor using ERDAS imagine. This process could be easier to be performed using ER ...
2
votes
0answers
123 views

ASTER mineral indices with VINR and SWIR data

I need to run a supervised classification on ASTER data in order to map a rock formation, which is composed of chert. There is no shortage of indices which can be used to highlight silica rich ...
3
votes
1answer
166 views

Is the bilinear resampling technique appropriate for the projection of ASTER data?

I need to project some ASTER data from a geographic coordinate system to a projected one. I have read online that the cubic resampling technique is the most appropriate for this purpose. However, ...
2
votes
1answer
410 views

How to improve classification accuracy for 3-band (RGB) imagery?

I am hoping to extract some simple vegetation features (sagebrush) from 1m 3-band (RGB) NAIP imagery. Unfortunately, there is no near-infrared band available for this dataset and I need to use this ...
7
votes
1answer
649 views

Ditch Extraction using LIDAR DTM (1m resolution)

I'm trying to extract ditches using the LIDAR DTM using the software eCognition but I am actually having a hard time since the paper where I based my workflow entitled "Ditches’ network extraction and ...
8
votes
1answer
548 views

River boundary (bank) extraction from LiDAR

Is there any way to extract a river boundary (bank) from LiDAR data and its products (DEM, intensity image and slope) automatically? Digitizing is very time consuming.