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1 Replies and 1142 Views
Band math expression 1142 1
Started by Deleted User
Hi Forum:
I am having a problem with a function. this is expression to calculate TDVI (transformed difference vegetaion index) and the value should be between -1 and 1 but I am getting all values >0 and beyond 1. the below is my band math equation.
FUNCTION td1,b1,b2
tdvi = 1.5* ((float(b1)-float(b2))/(float(b1*b1)b20.5)^0.5)
RETURN,tdvi
END
To understand better the situation here is the equation in excel, this works well though.
=1.5*(B3-A3)/SQRT(B3*B3A30...
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1142 |
08 Dec 2010 09:22 AM |
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0 Replies and 1250 Views
Multiple Band Mosaic Issue? 1250 0
Started by Deleted User
Hi all.
I am attempting to merge multiple data sets using the georeference mosaic tool. Specifically, I have a large gray scale base image and 3-band RGB file I have overlayed with the RGB representing three mineral units. Setting the RGB files "Data Vale to Ignore" to the zero value of the RGB allows only the non-zero mineral pixels to show up great in the mosaic window.
However, when I apply the mosaic creating a new file everything is georeferenced properly except the col...
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1250 |
07 Dec 2010 02:03 PM |
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1 Replies and 1513 Views
Negative Values in Linear Unmixing 1513 1
Started by Deleted User
Hi,
I keep getting too many negative values (60 of pixels) when preforming linear unmixing. In other words, a pixel will have -25 green vegetation. Applying gains to my "pure" spectra helps, but doesn't alleviate the problem.
What do these negative numbers mean exactly
Thanks!
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1 |
1513 |
01 Dec 2010 12:50 PM |
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1 Replies and 995 Views
envi standard file 995 1
Started by Deleted User
hello
I cannot open ENVI standard file in IDL programming language.Please help me in this regard how to open the file.The file is hyperspectral image,size 33990000bytes about oil palm plantation.
thanks
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1 |
995 |
30 Nov 2010 12:58 PM |
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0 Replies and 1074 Views
ROI creation after PPI for n dimension visulaiser 1074 0
Started by Deleted User
1. I did PPI on an MNF file and I am getting a chequered image. is that normal because i heard we get a bit file image and i hope its nothing crazy if yes help me :D
2. then going to create a roi from the ppi.
http://geol.hu/data/online_help/DefiningRegionsOfInterest.htmlwp1062570
I did the step only once, that means i have only one band (i put threshold from 1-506) :D
3. So after PPI and roi, I am going to o nD visulaiser.
a. If input of nDvisualiser is t...
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1074 |
29 Nov 2010 03:52 PM |
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0 Replies and 1155 Views
Band Math with a Hyperspectral Dataset 1155 0
Started by Deleted User
I'm working with a hyperspectral dataset and a vital step in my preprocessing involves dividing every band by a value of 20.
Is there an efficent manner that this can be done The band math tool only work with one band at a time.
How can I divide all 50 bands by 20
Many thanks,
O
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0 |
1155 |
26 Nov 2010 10:29 PM |
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0 Replies and 992 Views
Hi Everybody 992 0
Started by Deleted User
I am working with ETM SLC-off images, and i an unable to found the software developed by NASA "Frame_and_Fill_win32", can anybody help me as where i can manage the software.
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0 |
992 |
26 Nov 2010 04:31 AM |
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1 Replies and 1227 Views
DEM extraction module 1227 1
Started by Deleted User
Hi, I want to know how this module functions. I need to obtain countours from an ASTER image (it has 3 bands), but I don't know how can I extract data points from the image. I can do this in Globbal Mapper, another soft, but I have no idea with ENVI.
Please I need help urgent!! Thanks a lot!
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1 |
1227 |
25 Nov 2010 05:38 PM |
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1 Replies and 1283 Views
NaN value 1283 1
Started by Deleted User
Dear All!
I would like to ask a question about 'NaN' data. How can I replace all my 'zero' value pixels with value 'NaN'.
I tried to used Band Math:
(b1 eq 0)* 'NaN'
but it is failed.
Could you help me, please!
I am worry about 'zero' values because I want to create a composite image from several images with cloud masks ('zero' values).
Thank you very much for your help in advance!!!
With kind regards, Zoya
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1 |
1283 |
25 Nov 2010 06:15 AM |
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1 Replies and 1110 Views
Resizing data spatially by shapefile 1110 1
Started by Deleted User
Dear User,
I'm Sabber from Dhaka, recently working on deforestration of Dhaka city. For that reason i need to resize the NDVI raster result of the Dhaka city only. But whenever i do it, instead of cliping the exact dhaka city it clips like a rectangle. But i need to be clipped the exact as the shapefile. can anyone please tell me the technique to do it.
Sabber Ahamed
Jahangirnagar University
SaVar, Dhaka
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1 |
1110 |
24 Nov 2010 05:49 AM |
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0 Replies and 1091 Views
Solar irradiance in FLAASH 1091 0
Started by Deleted User
Hi everyone,
does anyone know which value (or a set of them) FLAASH considers for solar irradianceI read that MODTRAN allows to use a specific solar spectrum but I do not know how it is implemented in FLAASH.
Thanx
Michele
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1091 |
24 Nov 2010 03:57 AM |
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1 Replies and 1492 Views
Unmixing RMS Error 1492 1
Started by Deleted User
I ran a linear unmixing model that resulted in a mean RMS of 0.003365. The ENVI Help says that the units are meters. How do I interpret this number in the context of an unmixing model
Is this RMS reasonable
Thank you.
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1 |
1492 |
23 Nov 2010 05:03 PM |
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0 Replies and 1888 Views
Visual Fortran run-time error 1888 0
Started by Deleted User
I am getting "Visual Fortran run-time error" while performing atmospheric correction using FLAASH tool. The next line of the message is "forrtl severe (9): permission to access file denied, unit 20, file H:\ITT\IDL71\lib\hook\acc_modroot.mc". I'm using ENVI 4.7 on WinXP SP3 32 bit machine (Sensor specification: Unknown Multispectral; user defined filter function, wavelength and calibration).
Any suggestions
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0 |
1888 |
22 Nov 2010 09:01 PM |
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0 Replies and 1141 Views
Dark Subtract to Landsat Calibration 1141 0
Started by Deleted User
Hi,
I'm trying to use the Landsat Calibration tool after I've done a Dark Subtract, but I get an error saying that Landsat Calibration only works on single bands. The Dark Subtract has 6 bands, however the original Landsat TM files has 6 bands as well.
What do I need to do to run a Landsat Calibration after a Dark Subtract
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1141 |
22 Nov 2010 03:54 PM |
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0 Replies and 1091 Views
DEM extraction error 1091 0
Started by Deleted User
While extracting DEM using worldview-2 stereopair, Im facing an unusual error which says "Array dimensions must be greater than 0".
I SUCCESSFULLY COMPLETED FIRST 6 STEPS OF DEM EXTRACTION WIZARD .i.e GENERATING TIE PIOINTS WHILE BUILDING THE EPIPOLAR IMAGES, IM FACING THIS PROBLEM.
Thanks in advance
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1091 |
22 Nov 2010 04:31 AM |
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6 Replies and 1278 Views
MNF transform a small problem 1278 6
Started by Deleted User
I need to Do MNF for an image.
1. I coolected the values from near by pixels and stored in the spectral library using. spectra->spectral library-> spectral library builder -> First input spectrum.
2. After creating and saving the ASCII file and the spectrum library i wanted to Forward MNF transfrom
3. Transform -> MNF rotation -> forward rotation -> estimate the noise stastics from the data . I load the spectal library and I cant click OK because it need to be masked and I cant do t...
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6 |
1278 |
19 Nov 2010 01:35 PM |
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0 Replies and 1180 Views
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Started by Deleted User
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1180 |
18 Nov 2010 03:58 PM |
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0 Replies and 1143 Views
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Started by Deleted User
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1143 |
18 Nov 2010 03:29 PM |
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1 Replies and 1010 Views
Verifying flaash results landsat ETM 1010 1
Started by Deleted User
Hi
I applied the flaash function in ENVI on a ETM image in order to get the reflectance value
but i have a problem in cheking the values that i obtained
i would like to know how it is possible to verify if what i did is correct and if i can now work with this reflectance file
Thank you
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1 |
1010 |
18 Nov 2010 08:37 AM |
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0 Replies and 1312 Views
write my essay 1312 0
Started by Deleted User
Whether you join a College or a University, you will find that writing essays on different subjects in the curriculum is a necessary condition for acquiring higher grades and eventually qualifying for a degree. Higher grades are naturally achieved on submission of quality essays. Would you be able to write premium quality essays Does the task appear humongous It certainly is not. Please don’t get intimidated. With a little determination and persistence, you will surely be able to accompl...
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1312 |
17 Nov 2010 10:45 AM |