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0 Replies and 1212 Views
Deliniating vegetation cover from landsat7 images 1212 0
Started by Deleted User
Hi, I'm quite new to remote sensing softwares, though i have a backgound in the theories. I have these landsat images that i have to extract forest cover from, and convert them to vector polygons. That's my main objective.
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I started in stacking my tiff bads into one image file, then deriving the ndvi using the ndvi tool (used the bands 3 and 4, red and near infrared). I did this to separate the vegetated areas from the non vegetated. Actually, I am stuck here. I believe that the flow of...
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1212 |
23 Apr 2009 05:51 AM |
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1 Replies and 1574 Views
maximum likelihood classification threshold problem 1574 1
Started by Deleted User
Hello,
I am a new user to ENVI and am having difficulty using the probability threshold function within the maximum likelihood classification module.&160; No matter what threshold I set (I have tried values from .0001 to .9) it doesn't seem to be able to classify any pixels (in other words, the return is an entire image that is "unclassified" except for masked out pixels.)&160; I am using a mask band, but I don't see how this would make any difference.&160; I am also working with r...
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1574 |
22 Apr 2009 08:06 AM |
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2 Replies and 1458 Views
Problem using ENVI functions on an Ubuntu's platform 1458 2
Started by Deleted User
Hello,
I am actually using ENVI to manipulate some PALSAR datasets. I can load and display them flawlessly with the "open external files" menu.&160;
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My problem begins when I have tried to use the "basic tools/resize data (spatial and spectral)" function. When I start this function, it displays properly the window to choose the dataset, but then the second window "Resize Data Parameters" is blank, I mean there is nothing displayed inside, it's complet...
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1458 |
21 Apr 2009 03:25 PM |
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1 Replies and 1218 Views
Orthorectifying QuickBird imagery 1218 1
Started by Deleted User
I am trying to orthorectify QuickBird imagery using a 2 arc second DEM grid file.&160; The program does not recognize this file.&160; Any ideas
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1218 |
20 Apr 2009 04:30 PM |
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3 Replies and 1298 Views
masks 1298 3
Started by Deleted User
I am trying to apply a mask on an image of a lake but all I keep getting is a blank image, does anyone know what I am doing wrong
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1298 |
20 Apr 2009 10:00 AM |
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1 Replies and 1789 Views
Background value for stack? 1789 1
Started by Deleted User
Hi all,
I know that we can set a background value when building a stack, but how do I do it when building a stack My input layers lave different resolutions and I do want to use bilinear interpolation. But I need ENVI to avoid interpolating the "data ignore" values. I tried changing the header in my input layers, with no success.
Thanks,
Naiara.
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1789 |
17 Apr 2009 03:05 PM |
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2 Replies and 1526 Views
linear spectral unmixing 1526 2
Started by Deleted User
Hello all,
Thanks for answering my problems, however, I am still stack.
1. Even though I chose unconstrain, I still got the same results after running linear spectral unmixing, that are negative and super positive for the fractions.
2. I did match filtering, but the results are the same as mentioned above.
3. What are algorthms to calculate minimum noise fractions&160; and fraction images&160; for linear spectral unmixing In my case, I&160;observed from the statistic data&160;the MNF ha...
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1526 |
17 Apr 2009 02:58 AM |
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1 Replies and 1300 Views
help in feature extraction in ENVI Zoom 1300 1
Started by Deleted User
Hello, I read the reference from ENVI Zoom Help file "Implementation of a fast algorithm for segmenting SAR imagery"&160; but the efficiency of my program is really low.
A image of 1000*1000 pixel , I have to iterate the calculation procedure for about 1 million times, about 20,000 seconds or 10 hours, But in ENVI, it only require 10 seconds, to do the same work.
Could you give some suggestion or tip to implementation this fast algorithm for segmenting provided by Robinson
than...
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1300 |
10 Apr 2009 08:14 PM |
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3 Replies and 1207 Views
SPEAR TOOLS - Change Detection Substractive 1207 3
Started by Deleted User
When using change detection (substractive)&160; in spear tools in ENVI version 4.5, if the bands of the image did not include information about the wavelength&160; the wizard prompt to define the B, G, R, NIR bands&160; of the images and continued with the process thereafter. In version 4.6.1 if you use images without band wavelength definition, the wizard won't prompt to define bands and won't continue with methods such as NDVI difference.
Has anyone seen this before Is it supposed to be l...
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1207 |
10 Apr 2009 05:21 PM |
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1 Replies and 1477 Views
Number of decimals in ENVI 1477 1
Started by Deleted User
Dear List,
At the moment I'm orthorectifying a Quickbird image using the rpb information and some additional GCPs.&160; When I enter the GCPs as UTM coordinates in the ground control point selection window using the restore GCP function&160; and using&160; the UTM projection settings, ENVI automatically sets the projection system again to latlong when you click on a point to see if its location is fine. Envi however does not change the coordinates to latlong. In this way ENVI sees the UTM co...
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1477 |
08 Apr 2009 08:47 AM |
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5 Replies and 2042 Views
ENVI - layers 2042 5
Started by Deleted User
I am trying to use layer stacking in ENVI, but so far without success. Here is the problem - I have a data image which opens in envi as a 1 band image, which for display purposes I generally use the zoom linear function and apply a color table to. This data is produced from ASTER or MODIS TIR data.
I want to display this image over thvisible or VNIR data, which for both instruments is at a different spatial resolution to the TIR.&160; Anyone know if this is possible in ENVI
Thanks
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2042 |
08 Apr 2009 08:28 AM |
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1 Replies and 1267 Views
Linear Spectral Unmixing 1267 1
Started by Deleted User
Dear all,
I&160;applied &160;linear spectral unmixing to map tropical rainforest on Landsat 7 image. However, I found some pixel&160;of the fraction&160;map have negatif or more than 1 values, even though the sum up of these fractions is 1. I&160;tried to collect the endmembers from the PPI and from the original image.&160;I chose constraint 1 when I ran it.&160;For my study areas, I collected endmembers for forests, shrubs, soil, river, and shade. Based on 2D scatter plot, I cannot&160...
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1267 |
08 Apr 2009 08:21 AM |
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1 Replies and 3287 Views
How to get rid of strip lines from the USGS landsat scenes 3287 1
Started by Deleted User
Hi ENVI people
Currentlly, I have proble on how to get rid of&160; the strip(solids black) lines in the USGS landsat scenes . You can tell that the infomation is there if I manage to remove the lines. Any assistance is appreciated. I downloaded the Landsata scenes as zip file( with TIFF)&160; using USGS global visualization viewer at http://glovis.usgs.gov.
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Regrads
&160;
Yohannes
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1 |
3287 |
02 Apr 2009 09:06 PM |
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0 Replies and 1219 Views
How to get rid of strip lines from the USGS landsat scenes 1219 0
Started by Deleted User
Hi ENVI people
Currently, I have problem on how to get rid of&160; the strip(solids black) lines in the USGS landsat scenes . You can tell that the infomation is there if I manage to remove the lines. Any assistance is appreciated. I downloaded the Landsata scenes as zip file( with TIFF)&160; using USGS global visualization viewer at http://glovis.usgs.gov. Could there be other&160; way of downloading or option to remove the lines within ENVI
&160;
Regrads
&160;
Yohannes
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1219 |
02 Apr 2009 08:36 PM |
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2 Replies and 1172 Views
Question about accuracy 1172 2
Started by Deleted User
We use FLAASH to atmospheric correction of QUICKBIRD data, We got 81 also we did QUICKBIRD without atmospheric correction we got 71 accuracy. How do you think about this accuracy&160;
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1172 |
02 Apr 2009 03:54 AM |
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1 Replies and 1408 Views
MODIS - MOD35 cluod mask 1408 1
Started by Deleted User
Hi,
Does anyone know how to import and interpret MOD35 cloud mask data in ENVI It's in a bit-field format (http://modis-atmos.gsfc.nasa.gov/MOD35_L2/format.html) but when I import the HDF file into ENVI it does not recognise the bit/byte array and seemingly imports it to 6 bands with pixel values which I'm unable to intepret.
The cloud mask should look something like below (which i can get to work in HYDRA) with a bit flag for clear/cloudy/probably clear/uncertain but i'm not sure how to get ...
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1408 |
01 Apr 2009 05:43 PM |
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6 Replies and 1248 Views
Q: Spectral Analyst 1248 6
Started by Deleted User
Hi, I have alot of ROI mean-spectra I want to identify using the Spectral Analyst feature. Is there any way of saving the Spectral Analyst score results to file It seems that even marking text/ copy does not work in that specific results dialog. Envi 4.4.
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6 |
1248 |
01 Apr 2009 02:47 AM |
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1 Replies and 1233 Views
Save as spectral library 1233 1
Started by Deleted User
If anyone could help, that would be great. I'm just trying to save some spectra as a spectral library. I don't know any of the code,&160; I just do the clicking. I just want to know, in the box that pops up when outputting a spectral library, what is the Z plot range they want you to put in Anything else people could tell me would be great.
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1233 |
31 Mar 2009 12:57 PM |
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1 Replies and 1291 Views
user move routine 1291 1
Started by Deleted User
Hello,
do anyone knows if it is possible to set up programatically the user defined move fonction in ENVI
thank you!
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1291 |
31 Mar 2009 12:39 PM |
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2 Replies and 1371 Views
ROI-tool deletes phase data? ERS scenes 1371 2
Started by Deleted User
I have used EVF file to remove sea from land data in two ERS scenes. I use the ROI-tool and I subset data through the ROI-EVF file. The result is a subset file (.pwr or slc) with power or magnitude data, but no phase data. Phase data are the important for the interferogram generation. Does anybody know how I can extract only the land data on .slc files of ERS
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1371 |
31 Mar 2009 09:04 AM |