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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85 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
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2answers
34 views

What reflectance curve

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 the ...
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0answers
14 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 ...
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1answer
42 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 ...
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1answer
28 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 ...
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1answer
19 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?
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1answer
59 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 - ...
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1answer
35 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 ...
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2answers
197 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 ...
1
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1answer
35 views

Feature extraction in remote sensing!

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 ...
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0answers
20 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?
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3answers
67 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 ...
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2answers
113 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?
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1answer
28 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
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0answers
60 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 ...
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0answers
46 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
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0answers
59 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.
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0answers
7 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.
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1answer
73 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 ...
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0answers
95 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
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1answer
74 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
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1answer
22 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 ...
8
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1answer
221 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
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1answer
32 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 ...
3
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1answer
117 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
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2answers
66 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 ...
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0answers
43 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 ...
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0answers
19 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 ...
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2answers
92 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
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1answer
128 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 ...
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1answer
35 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
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1answer
32 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 ...
3
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0answers
41 views

At surface reflectance values

I have calculated at sensor reflectance for a multispectral image and preformed atmospheric correction. The reflectance values for the visible and NIR bands are between 0.2 to 0.01 for surface eg veg, ...
2
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1answer
60 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 ...
5
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3answers
199 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 ...
4
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3answers
49 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 ...
3
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1answer
164 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 ...
3
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0answers
46 views

How to detect temporal changes using ArcGIS?

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
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1answer
70 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
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0answers
22 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
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1answer
59 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
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1answer
57 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 ...
6
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1answer
150 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
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1answer
191 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.
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0answers
59 views

Batch GDAL_Calc multiple band calculation

I have a question concerning gdal_calc. I´m running windows 7 64b and am working from the OSGeo4W shell. I have multispectral images that need to be prepared for analysis but they are not saved in a ...
0
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1answer
69 views

Extract elevation data from Landsat / MODIS imagery?

Just curious, have anyone tried to extract elevation data from LANDSAT or MODIS imagery? So far, I came across one journal by Toutin who did so using adjacent LANDSAT 7 imageries. Results seem pretty ...
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0answers
43 views

Urban Heat Island USING ENVI

I have downloaded MODIS images for a specified area.. Its my first time that I am working on UHI (Urban Heat Island).. I need to know the methods to work on it.. I am using ENVI for this.
1
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1answer
46 views

Easy Guide to ESA satellite data?

Can anybody provide user friendly guidance to ESA datasets? What is available? When will new stuff be available? I struggle to work out what might be interesting amongst the many websites and their ...
3
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1answer
105 views

Dark Object Subtraction QGIS

I'm trying to do Dark Object Subtraction (DOS) for a Spot2 and 4. I have calculated the TOA reflectance and now want to get the at surface reflectance. Using QGIS I would like to know how I can do ...
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0answers
133 views

Calculating TOA reflectance from Radiance using Erdas Imagine for a Spot2 image

Using the SPOT equation ρ = π L/[E cos (θs) d-²] to calculate TOA reflectance from Radiance. L was calculated using this equation [L = (X/A) + B] d was calculated by converting date to julian day ...