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9 votes

EVI and NDVI range value

You are right: the range of the NDVI is limited to values between -1 and 1 due to its' normalization properties. The negative limit of -1 will be reached if you encounter maximal reflectance (1) in ...
gurgli's user avatar
  • 176
7 votes
Accepted

How to extract single band from multi-band radiometry raster using R?

It is not clear on weather you want to subset bands upon reading into R or extract a single band from an existing raster stack. Once illustrated, both are quite simple. We can use the 3 band R logo ...
Jeffrey Evans's user avatar
6 votes
Accepted

Rotate ENVI hyperspectral imagery with GDAL

The rotation can be changed from the python API. The raster grid size, position and rotation parameters can be accessed with the GetGeoTransform() method, and they can be changed with the ...
user6072577's user avatar
  • 1,582
4 votes
Accepted

Differences in the longitude and latitude between a LiDAR DSM and an optical image

There is nothing wrong with your data. It is just the fact that OS still issues coordinates in OSGB36, while Google uses WGS84: So you have to assign EPSG:4277 to your degree coordinates, or EPSG:...
AndreJ's user avatar
  • 76.7k
4 votes
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Writing band names into header (ENVI file type) using GDAL?

You need to use the SetDescription method of the raster band object. rb = destination.GetRasterBand(1) rb.SetDescription('band hello world') rb.WriteArray(myArray) $ cat /tmp/test.hdr ENVI ...
user2856's user avatar
  • 67k
4 votes
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Read aviris data with python

You can use numpy's reshape and transpose functions to reconstruct the desired result. And the dimensions of the "desired result" is used in one of two forms which is often up to the user to decide: ...
Mike T's user avatar
  • 42.2k
4 votes

Explaining ENVI equations?

ge means "greater or equal" (i.e. >=) gt means "greater than" (i.e. strictly greater, >) le means "lower or equal" (i.e. <=) lt means "lower than" (i.e. strictly lower, <) et is probably ...
ArMoraer's user avatar
  • 5,639
3 votes
Accepted

Classifying different surfaces having almost similar Reflectance responses

The spectral signature that you show on your post are definitely different, therefore you should look at other issues. I would first check that my training samples are correct and adapted to the ...
radouxju's user avatar
  • 49.8k
3 votes
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Calculating latitude and longitude values for each pixel corner?

Do I need to some information about the tiff file in order to proceed? You'll need to know the size of the pixels for a start, and you could use GDAL for that, see: How do I find out the resolution ...
nmtoken's user avatar
  • 13.5k
3 votes
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Opening .tab files associated with .lbl files in ENVI

The .tab file can be easily opened in notepad. There you can decide which column information is required for your work and then read this file using python easily. Then, write the required columns (...
MAYANK SHARMA's user avatar
3 votes
Accepted

Why getting wrong NDVI values resulted from scaled reflectance in ArcMap?

you should either set the calculation in float Float(("nir"-"red"))/("nir"+"red") or multiply by 100 (100*("nir"-"red"))/("nir"+"red"). Your strange results are due to conversion to integer (the ...
radouxju's user avatar
  • 49.8k
3 votes

Is there a Post-classification Majority Analysis feature on Google Earth Engine (Similar to ENVI)?

Here is an article by the Earth Engine team that does a little explaining on morphological operations within Earth Engine Fo your case, you may be able to get away with using image.focal_mode() (or ...
Kel Markert's user avatar
  • 1,128
3 votes

Digitizing photographs of a map

This is called "georeferencing" and requires knowing the real coordinates (latitude/longitude) of some features on the image. A Georeferencer program will input your image, then you have a ...
Spacedman's user avatar
  • 65k
2 votes

substitute for landsat 7 for land classification?

SPOT has similar characteristics and is often used as a substitute. ASTER has similar characteristics and is often used as a substitute. Both will have the required coverage dates. ASTER will not ...
If you do not know- just GIS's user avatar
2 votes

Conditional statement ENVI

A bit late, but this expression would work using ENVI Band Math: (b1^2 - b2^2) * ((b1 NE 0) AND (b2 NE 0)) HTH.
lbusett's user avatar
  • 221
2 votes

How to assign mean values from different windows sizes to point feature?

Do you use model builder? It takes a few steps but you could buffer your points and rasterize them and use this raster as input as zones for zonal statistics as table. Then this table can be joined to ...
PythonStudent's user avatar
2 votes

How to assign mean values from different windows sizes to point feature?

Why not use the "extract values to points" tool (Spatial Analyst) as step one. That will give you the elevation value on each point. Then use a 3x3 fishnet and perform a spatial join with the point ...
jbchurchill's user avatar
  • 4,489
2 votes

calculate NDVI for several images

You need NIR and Red band for the calculation of NDVI. These bands corresponds to the 3rd and 4th bands of Landsat 7 Images. You can use Spectral Indices tool (Spectral > Vegetation > NDVI) for the ...
Ayda Aktas's user avatar
2 votes

How to open a Higher Level Landsat image with ENVI 5.2?

Landsat L1 product metadata is contained in .MTL archive, L1 level are Landsat products in DN or TOA reflectance. Higher Level Landsat Image in BOA reflectance has another kind of metadata structure. ...
aldo_tapia's user avatar
  • 13.7k
2 votes

Opening rrd file in ENVI 5.3

ENVI has a data type support page and doesn't list RRD as a supported data layer. Supported File Types Perhaps you can use a file that is a supported data layer to be able to open in ENVI 5.3, as per ...
whyzar's user avatar
  • 12.1k
2 votes
Accepted

Topographic correction in ENVI

ENVI doesn't have topographic correction tool. You can do it as a secondary product using ATCOR trough ENVI. If you don't have license for that, I recommend you to correct your scenes via QGIS or R.
aldo_tapia's user avatar
  • 13.7k
2 votes
Accepted

How to export latitude and longitude values of each pixel corner?

There is no need of fancy software like ENVI or IDL If the tiff files have an accompanying .tfw file (a.k.a. world file), you can open that file in a text editor and all the information you need is ...
Camilo Rada's user avatar
  • 1,219
2 votes
Accepted

Using COSI Corr Interior Orietation Fiducial Marks in UAV Imagery?

Fiducial marks are the characteristic markers placed at the margins of aerial imagery. XY coord refers to the fiducial mark location (in mm) and XY loc is the image file coordinates in pixel. Remember ...
Sotiris Valkaniotis's user avatar
2 votes

ENVI 5.1 - ANN Classification - Background was classified into one of the class

It has been long time since I used ENVI, but I remember that you can draw a region of interest (ROI) covering only the image data without the black background, and then use the ROI to subset the image....
ahmadhanb's user avatar
  • 41.1k
2 votes

Read aviris data with python

Ok, after some more research I found the answer: Unfortunately, numpy has no reshape order that correspond to BIL (Band-interleaved-by-line). However, you can resort it by yourself with numpy. This is ...
Lau's user avatar
  • 117
2 votes

Explaining ENVI equations?

These are relational Operators. See here: https://www.harrisgeospatial.com/docs/Relational_Operators.html I'm not sure what et stands for, but using these, the equation becomes: (b1 <= 0) * 0 + (...
Devdatta Tengshe's user avatar
2 votes

Converting ENVI grid to Esri shapefile?

ENVI grids are a simple flat-binary raster file with an accompanying ASCII header file You don't need to convert an ENVI grid to a shapefile to open in ArcMap, it can open it as is. I don't use ...
user2856's user avatar
  • 67k
2 votes
Accepted

GeoTIFF to ENVI GDAL translation causes rotation

You need to gdalwarp to fix the rotation: gdalwarp -of VRT dgm1_32372_5680_2_nw.tif dgm1_32372_5680_2_nw.vrt Creating output file that is 2000P x 2000L. Processing input file dgm1_32372_5680_2_nw.tif....
user2856's user avatar
  • 67k
1 vote

Identifying pixels with sun glint in a satellite image (for atmospheric correction)

@user18058 I have thought that you solved your problem about the sun-glint removal. I using Lyzenga algorithm to correct sun-glint in RGBNir images taken using DMC Camera and the results were ...
César de Paula's user avatar
1 vote

Open and read spectral library as array in Python?

I'm reading ENVI spectral libraries using spectral import spectral as sp1 import pandas as pd SpecLib = sp1.envi.open('path to spectral library') SpecLib_df = pd.DataFrame(index=SpecLib.names, data= ...
user88484's user avatar
  • 1,829

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