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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7
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262 views

Frontal Detection of sst & Chlorophyll image

I am working on sea surface temperature satellite images and looking for delineating gradients in open source on the basis of temperature. Is there any tool like Cayula and Cornillon front detection ...
5
votes
0answers
143 views

How do I open MOD17A3 in ENVI such that it is properly georeferenced?

I am using ENVI 5.1 on Windows 8. I am trying to open a MOD17A3 (MODIS Net Primary Productivity standard product - L4) .hdf file which I downloaded from the USGS website. I am still a beginner at ENVI,...
5
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0answers
627 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 ...
4
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0answers
24 views

Is there a way to use the GDAL C++ API to find areas of overlap between two SAR images?

I have a bunch of SAR images (about 1 GB each) on which i need to do some image processing. Each image is georeferenced and there is significant overlap between each pair of images in the set ie. one ...
4
votes
0answers
39 views

Ice type differentiation using satellite data

I would like to classify glacial area by categories of snow (if there is) and ice, but what's most important: between old ice and fresh ice. They have different properties that are possible to ...
4
votes
0answers
116 views

Counting number of plants in area using images from UAV?

How do I count the number of pineapple plants in a 1-hectare block? I have heard of these algorithms but I don't know how to do it. I'm still a newbie of QGIS, ArcGIS and ENVI. I have the NIR, RGB, ...
3
votes
0answers
81 views

Classify image using segmentation analysis using QGIS and OrfeoToolbox

My first question on stackexchange (sorry for my english language)! I use stackexchange often to understand GIS principles and workflows. I wasn't able to find a answer. For this project we made a RGB ...
3
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0answers
46 views

How to classify difference surfaces having almost similar Reflectance responses?

I am using ENVI 5.3 to classify a Region of Interest clipped from Landsat 8 OLI. I have already performed calibration of my DNs by transforming it into Radiance and derived Reflectance image using ...
3
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0answers
15 views

Snapping vectors to vertices for ROI delineation?

I am trying to manually extract a set of ROIs in ENVI 5.0. However, I can't seem to successfully line up the vector to be flush with the boundary of the pixels, which means I don't have fine-tune ...
3
votes
0answers
74 views

Using original Landsat multispectral image or pan-sharpened image in land cover classification?

I am currently creating land cover maps of a number of national parks across Asia from Landsat 8 imagery and also later from SPOT imagery. I plan to use supervised classifications in ERDAS IMAGINE and ...
3
votes
0answers
41 views

Differences between mWm-2sr-1(cm-1)-1 and W/m^2 * sr * um

I'm confused about the use of this quantity. For example eumetsat on pag. 16 radiance is equal to: Physical Units = Cal_Offset + (Cal_Slope x Level 1.5 Pixel Count) expressed in mWm-2 sr-1 (cm-...
3
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0answers
185 views

Import GPS SINEX (for velocity analysis) into Sarscape or processing with others software

I try to import GPS snx. into Sarscape 5.2 (use GPS Import tool) and getting error 115) ) gps_type : [sinex] 116) ) generate_kml : [OK] 117) ) generate_shape : [OK] 118) ) ...
3
votes
0answers
34 views

Guide to aerial or space data types and availability

I am overwhelmed by the variety of types of satellite and aerial data (images?) available online. For example, at the USGS Earth Explorer data page, I see AVHRR; CEOS;Ikonos and OrbView; EO-1; GLS; ...
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 ...
3
votes
0answers
127 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 ...
3
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0answers
148 views

Landsat TM, ETM+: what are radiometric calibration coefficient of each sensor to convert DN to radiance

The Landsat TM Image data that comes with zipped folder contains metadata text file in which all necessary information have been written. In order to further process that data, first DN to radiance ...
3
votes
0answers
473 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 easy-...
3
votes
0answers
120 views

Thermal Map Data

I am curious about making a thermal map to display where the hot spots and where the cool spots in a community are. Obviously the roads will be hot and the shaded areas with trees will be cool but ...
3
votes
0answers
89 views

How is Canada Vector Data (CanVec) hydrology data collected and updated?

Canada is vast and collecting any geographic data must be a monumental task. Natural Resources Canada provides a free access to a comprehensive Canada-wide topographic data now refereed to as CanVec (...
3
votes
0answers
116 views

Using Quickbird to discriminate vegetation response and spectral signatures - which season?

I have a study area in N. Florida loblolly pine plantation with 3 treatments (drought, fertilization, drought+fertilization, control) and 4 replicate plots. All plots will be in the same scene. These ...
3
votes
0answers
248 views

How to merge SeaWiFS and MODIS data or use other merged products?

I hope to produce a time-series for sea surface temperature (SST) and chlorophyll-a (Chl-a) for use in MaxEnt without the use of arcgis, preferring Python tools to others. I am new to satellite data ...
2
votes
0answers
37 views

Negative reflectance values after topographic corrections (cosine correction and modified Minnaert correction)

I am trying to manually correct the surface reflectance values of some Landsat 7 and 8 images. I'm using Minnaert modified method, which uses the cosine correction as one of its inputs (see below the ...
2
votes
0answers
31 views

MODIS Imagery Orthorectification (Open Source)

I am looking for an open source free software/tool for orthorectification/Geometric terrain correction of MODIS imagery. I have looked at ESA (European Space Agency) SNAP but this sensor type is not ...
2
votes
0answers
22 views

ModelBuilder Iterations and Data Storage

OK, so here's my situation. I have a large series of rasters divided into two categories, let's call it Type A & Type B, a pair for each of a few hundred date/time snapshots. The date/time for the ...
2
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0answers
12 views

Image sizes for VHR remote sensing image

I need to compare three or four different segmentation algorithms on very high spatial resolution remote sensing images, with a range between [0.31,1.00] meters/pixel. What image size could you ...
2
votes
0answers
62 views

Calibration error for Sentinel 1 image in SNAP toolbox

I am working with a Sentinel 1 SLC IW image (VV+VH) and trying to calibrate the data in the SNAP toolbox. However, it keeps returning the error "cannot construct data buffer" Does anyone have any ...
2
votes
0answers
41 views

How to determine Visibility Map for Atmospheric Correction

As per Grass wiki: https://grasswiki.osgeo.org/wiki/Atmospheric_correction the atmospheric correction could be done using a visibility raster in conjunction with an elevation raster. With regards to ...
2
votes
0answers
58 views

TIMESAT seasonality data (MODIS EVI)

I am trying to get seasonality parameters from MODIS EVI (MOD13Q1) for Indonesia. I have loaded data from 2013-2015, but the plotted time-series is shifted from what I expect. Indonesia has rice-...
2
votes
0answers
74 views

16-day-MODIS NDVI values seem to be wrong compared to my soil moisture ground data!

I'm using MOD13Q1 product of MODIS for estimation soil moisture. As I know, this product is made up of the maximum value of NDVI of each pixel over 16-day calculated NDVI values. The problem is that ...
2
votes
0answers
102 views

Calculating Aerosol optical thickness from Landsat 7

EDIT I have added question down I am reading one paper and I found method to retrive AOT from landsat 7 image This should be simplifield equation, because they assumed observation zenit as 0. Than ...
2
votes
0answers
67 views

GIS or Remote Sensing technique to map sub-surface features?

I am trying to delineate agriculture tile drainage in Midwest. Does anyone know of any GIS and/or sub-surface remote sensing techniques to detect tiles/objects buried in shallow depth of soil? Does ...
2
votes
0answers
55 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
0answers
58 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 ...
2
votes
0answers
77 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 ...
2
votes
0answers
337 views

Format of raw LiDAR data (time-of-flight data)

I am doing a project where I need to simulate LIDAR data, and I am looking for specifications on how raw LIDAR data looks. I want the format of the data before it is translated to x,y,z coordinates (...
2
votes
0answers
461 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 ...
2
votes
0answers
49 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 ...
2
votes
0answers
133 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 ...
2
votes
0answers
156 views

R: Can raster predict function pass to predict.rfsrc (a prediction function in a parallel verion of RandomForest)?

It seems that raster predict function can pass to predict.randomForest by setting the "type='response'". I am using a parallel version of randomForest package called the "randomForestSRC" and I am ...
2
votes
0answers
45 views

differentiating stone houses from barren rock in ArcGIS 9.3

I'm working in ArcGIS 9.3 trying to differentiate stone houses (often red brick roofs) from barren rock in a typical Mediterranean karst region via remote sensing. I have been using Landsat imagery. I ...
2
votes
0answers
51 views

“Back calculating” to quantify the “atmospheric effect” of water vapor or other gases in a “corrected” hyperspectral image using QUAC?

I know that when using FLAASH in ENVI, you can produce a water vapor map (caveats considered) from your atmospheric correction. My question is if it is possible to "back-calculate" a water vapor map ...
2
votes
0answers
702 views

Question related with 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 ...
2
votes
0answers
260 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 ...
2
votes
0answers
740 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 .
1
vote
0answers
14 views

Complex Coherence with SNAP or SarScape

is it possible to estimate the complex coherence between two RADARSAT-2 SLC images with SNAP or SarScape? If I try to estimate the Coherence I get only float data but I need it in a complex form.
1
vote
0answers
18 views

Why can't get correct RGB img of Landsat 8 using np.dstack

I use np.dstack to stack Band4, Band3, and Band2 of Landsat8 data to get ture color image,I use code from Milos Miljkovic, but the result looks incorrect. import numpy as np from matplotlib import ...
1
vote
0answers
31 views

Combining hyperspectral bands to form a multispectral image?

I understand that the difference between the two are the number and width of the bands. Given a hyperspectral image, is it possible to 'convert' it to multispectral ? In this paper for example, the ...
1
vote
0answers
15 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 ...
1
vote
0answers
24 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 ...
1
vote
0answers
12 views

Issues with using FLAASH on GeoEye data

I am trying to carry out a FLAASH atmospheric correction on radiometricaly corrected GeoEye-1 spatial image (working within ENVI). I am geting the wrong results from my FLAASH correction and belive ...