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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2
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1answer
209 views

How to handle MOD13Q1 NDVI Product Quality Assessment(QA) flags?

I am working on MOD13Q1 NDVI Product and i want to apply Savitzky Golay filter for smoothing Ndvi time series using Quality Assessment(QA) flags. I studied MOD13Q1 NDVI help file and found that ...
3
votes
1answer
94 views

How to interpret MOD44B 8-bit quality layer

I have 15 annual MOD44B (vegetation continuous field) HDFs for 2000-2014, working in Arcmap 10.2. Each contains several bands. The two I'm concerned with are "percent tree cover" and "quality." The ...
2
votes
1answer
47 views

Rigorous geometrical models for InSAR imagery?

I'm looking for rigorous geometrical models for InSAR imagery. I'm familiar with the rigorous models for SAR images, but I don't know the model for InSAR. I searched through the internet, but I didn't ...
3
votes
3answers
282 views

What should come first-Radiometric calibration or co-registration?

For a pair of images,in the pre-processing of satellite images, which step should come first- Radiometric calibration or co-registration?
1
vote
1answer
166 views

Enhanced Vegetation Index Value

Can enhanced vegetation index have values greater than 1? I am using the ENVI software to calculate enhanced vegetation index (EVI) of a hyperspectral image and my EVI value range was from 0 to 1.9. ...
3
votes
3answers
152 views

Multi Temporal Images

I am new to remote sensing, so I would want to clarify my understanding of the meaning of Multi Temporal Images. As far as I understand, multi temporal images are multiple images of the same scene ...
1
vote
0answers
114 views

Format of SAR images

What is the format in which SAR images are stored? By format I mean when a SAR captures an image, it gets saved in what format? jpg? png? tiff? or there is some other special format? Is there a ...
0
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0answers
63 views

How to get multi-temporal InSAR data?

I am very much new to InSAR data. At the moment, i'm stuck at this website https://ursa.asfdaac.alaska.edu. Just wanna know, is it possible to get multi-temporal InSAR data for a particular region ...
3
votes
1answer
86 views

what does it mean to store cross products in SAR product data file?

I'm reading the UAVSAR data format For definition of two types of file we have: MLC files (.mlc): calibrated multi-looked cross products, floating point format, three files8 bytes per pixel, ...
3
votes
1answer
247 views

What is multilooking?

Today I found a video on youtube for multilooking the data with NEST (Next ESA SAR Toolbox) and it seems that it produces square pixel out of rectangular SAR pixels. Does it operate as simply as ...
2
votes
2answers
227 views

Deciding variables for unsupervised image classification?

The results of an unsupervised image classification may vary A LOT depending on the variables you use from the beginning. These are the variables for the tool in ArcGIS:number of classes, minimum ...
0
votes
1answer
51 views

aerosol optical depth

i want to extract aerosol optical depth on land using modis it seems like I need a value from one of these parameters between Corrected_Optical_Depth_Land and Corrected_Optical_Depth_Land_wav2pl but ...
6
votes
1answer
142 views

Free open satellite or other remote sensing data for night time?

I usually work with daytime satellite images to do some image classification (mostly Landsat data from the USGS EarthExplorer). Right now I'd like to check at some night time images to work on city ...
2
votes
1answer
381 views

Calculating NDWI in Erdas IMAGINE 2014

I'm using MOD09GQ product of MODIS to calculate vegetation indices in Erdas 2014, and I was able to extract NDVI using Erdas Model Builder. What is the formula I should use in model builder for ...
0
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0answers
37 views

Problem using ENVI/IDL ENVITask('BuildBandStack')

I am trying to stack 2 bands together from 2 different landsat images using ENVITask('BuildBandStack'). These are landsat images from two different years, and Band 1 in both years. When I run my code ...
1
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0answers
58 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, ...
0
votes
1answer
179 views

Is there any packages to download landsat image by shapefile boundary in R or python? [closed]

I want to find a package which can automatically download images within a predefined administration boundary (shapefile format). Does anyone know a package can conduct or simplify the process?
1
vote
1answer
290 views

Why is azimuth resolution worse than range resolution in Sentinel1 (SAR) [duplicate]

Why is the azimuth resolution in Sentinel (SAR sensor) worse than the range resolution? The table in this link gives the resolution for SLC products aquired in the different aquisition modes. In ...
0
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1answer
63 views

Is there any comprehensive book or online instruction on image segmentation techniques?

I'm looking for a source to learn theoretical basis of image segmentation techniques thoroughly. The desirable book, or other kinds of source you may know, should cover the techniques that are more ...
4
votes
1answer
115 views

Determining the best month for discriminating between different vegetation types?

I ordered and downloaded several (Surface Reflectance) Landsat 5-8 images from USGS Earth Explorer with the purpose of choosing a few of them to calculate some Vegetation Indices for each (NDVI, SAVI, ...
4
votes
2answers
167 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
1answer
141 views

Why does the peak of a mountain appear bright on Radar images

Why does the top of a mountain appear bright on a SAR (radar) image. I know that the peak of a mountain is subject to a layover effect, thus appearing closer on the radar image than the bottom part of ...
0
votes
0answers
22 views

Is this terminology I'm using is suitable for the field spatial analysis of time series?

I'm going to apply time series concepts to an satellite image, but instead of using time data located on the 'X' axis, I want to use spatial variations on that axis. In addition, the 'Y' axis keeps ...
2
votes
1answer
268 views

Difference between a spectroradiometer and multispectral sensor

Let's take as an example of a spectroradiometer MODIS, and as an example of a multispectral sensor the Landsat8 (OLI). What is the difference between these two sensors? Should we compare a ...
1
vote
1answer
37 views

Does satellite imagery have a unique azimuth for each of its spectral bands?

Does satellite imagery have a unique azimuth for each of its spectral bands? Is it right to say that if a sensor has 8 spectral bands, then it may have 8 different azimuth angle?
1
vote
0answers
86 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 ...
0
votes
1answer
73 views

Extracting Data from Raster based on Aspect Raster file

I have 2 rasters, ones shows aspect and another shows date of snow thaw. I want to extract the date of snow melt based on values from the aspect raster. For example I want all the snow thaw dates from ...
2
votes
0answers
53 views

Important to perform atmospheric correction when attempting to identify coral reefs?

I want to identify coral reefs using multi-temporal Landsat data and Lyzenga's Transformation method. In relation to pre-processing the image, should atmospheric correction be done or not? If not, ...
2
votes
1answer
81 views

Can a satellite go over the same area in different passes overtime

Can a sun-synchronous satellite (let's consider Sentinel-1) go over the same place, one time in an ascending pass and the next time (or few times after) in a descending pass?
2
votes
0answers
52 views

What does “Information [18]: Select at least one signature” in the semi automatic classification plugin mean?

I am using the semi automatic classification plug in to classify vegetation and water in a satellite image. I create training shp and signature list. When i hit "classification preview" it gives me ...
3
votes
1answer
118 views

Reading Synthetic Aperture Radar raster images using python

Is it possible to read and modify Synthetic Aperture Radar raster images using python? gdal is not able to understand their Type which is Binary (application/octet-stream). One can find sample radar ...
0
votes
0answers
26 views

What's the relationship between visibility and reflectance?

I'm having a problem with the atmospheric correction of remote sensing images. Until now I believed that increasing the visibility (or decreasing AOD) resulted in an increase in reflectance but now ...
0
votes
0answers
49 views

Geometric correction using topographic maps?

I am researching LULC change detection using Landsat 7 etm + image in 2000 and Landsat 8 image in 2014. Both are L1T images. Do I need to do geometric correction using topographic map for my study ...
0
votes
0answers
77 views

DEM input problem using ARCSI Landsat 8 batch processing

I'm trying to use ARCSI in Linux to process a batch of Landsat 8 images. I'm using the arcsibuildcmdslist.py to build the arcsi.py final command. I'm having problems in the input DEM ...
2
votes
1answer
109 views

Get resolution and whether right/left looking from sentinel metadata

Is it possible in Sentinel hub products to know the resolution of the product and whether the SAR was right or left looking at the scene? I know that it's possible to know if the SAR was operating in ...
1
vote
0answers
96 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 ...
3
votes
1answer
337 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 ...
1
vote
0answers
25 views

Change detection between two Landsat scenes? [duplicate]

I want to do time series analysis and find change in NDVI. I have rasters where each pixel is represented by some value at a time. Also I have same thing but represented by points. And I would like ...
3
votes
2answers
412 views

Raster image thresholding using python

I would appreciate if someone could guide me for applying thresholding technique to input raster image using Python. I intend to extract impervious surfaces from a high resolution raster such as ...
2
votes
2answers
317 views

land Use land cover classification

I am working on Land Use/Land Cover Classification of the Hindon river(India) watershed extracted using Aster DEM. Landsat 8 scenes had been used and mosaicked for the required AOI using the Watershed ...
3
votes
2answers
2k 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 ...
0
votes
1answer
131 views

Semi Automated Classification plugin (QGIS) error when trying to create ROI

When I try to create a new ROI through Semi-Automated Classification plugin (SCP) for QGIS, I keep getting a message saying: "It appears that SciPy is not correctly installed. Please, see this page ...
1
vote
0answers
244 views

NDVI calculation using ArcGIS 10.1

i have to derive NDVI from Landsat 8 image.. I used the following equation from landsat website with band 5 and band 4 using ArcGIS 10.1 Conversion to TOA Radiance OLI and TIRS band data can be ...
2
votes
2answers
571 views

How to atmospherically correct Landsat 8 data?

What is a simple way to atmospherically correct Landsat 8 data using Erdas 9.3 or ArcGIS 9.3?
2
votes
1answer
88 views

Landsat Surface Reflectancce product Python packages

I have to work with numerous Landsat surface reflectance product that I downloaded from http://landsat.usgs.gov/CDR_LSR.php. The product comes with a QA data with information on clouds and shadows ...
3
votes
0answers
23 views

Should Endmembers be Normalized for Linear Unmixing?

In biological spectral microscopy, the standard in the field is to use normalized endmembers in linear unmixing algorithms. In most cases, the endmembers are normalized to the maximum value. I have ...
0
votes
1answer
42 views

How do you digitize an ROI in envi 5.2?

Is there a way to digitize an ROI in ENVI 5.2 that is larger than the area shown in the viewer? I'm setting up labs for an intro to RS class, and the next step is to subset the image to get rid of ...
4
votes
1answer
292 views

How to compute NDSI in ArcGIS for Desktop?

How do I compute a Normalized Difference Snow Index (NDSI) in ArcGIS's Raster Calculator? I have a Landsat 8 scene (hdf4 format) that contains derived surface reflectance band-by-band. Each band is a ...
2
votes
0answers
74 views

Which preprocessing comes first for pansharpened imagery- atmospheric correction or orthorectification?

For pansharpened imagery, what preprocessing method to do first- is it atmospheric correction or orthorectification? From my readings, it seems the former but the rational polynomial coefficients or ...
3
votes
0answers
123 views

From Landsat spectral radiance (W/m2*sr*µm) to Global horizontal irradiance (W/m2) for mere mortals

We are working in a solar energy project to locate potential sites for solar panel farms. We are using the Landsat 7 panchromatic band to derive radiance with GRASS using i.landsat.toar (W/m2*sr*µm ...