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8 Replies and 2941 Views
How to count pixel in NDVI 2941 8
Started by Deleted User
Hello Dears,
I am using Landsat7 on ENVI. I calculate NDVI through Tools>Band Math (band 4 and Band 3).
Now, how can I classify the NDVI values, ( eg. 3.0-4.0 , 5.0-7.5 and so on).
Please let me know if you have some ideas.
Thanks,
Alvin
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8 |
2941 |
18 Mar 2011 07:26 AM |
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1 Replies and 1752 Views
ISIS .QUB files into ENVI 1752 1
Started by Deleted User
Hi All,
I am trying to get some ISIS .QUB files into ENVI. Has anyone developed a workflow to allow ENVI to do this I am trying to get some THEMIS data into ENVI 4.8 for analysis, but am having some issues.
Thanks
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1 |
1752 |
by Deleted User 16 Mar 2011 07:46 PM |
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0 Replies and 1326 Views
Random Sample 1326 0
Started by Deleted User
Hi everybody.
How can I generate a set of random sample that doesn't overlap with any training ROI
really appreciate if you can help me
thank you
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0 |
1326 |
15 Mar 2011 07:27 PM |
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3 Replies and 1579 Views
Hyperion atmospheric correction 1579 3
Started by Deleted User
Hi,
I have a hyperion hyperspectral image that I'm trying to preprocess.
I'm doing FLAASH atmospheric correction and I'm looking for the scale factors
I have seen the scale factors quoted as 400 for VNIR and 800 for SWIR, and I have also seen the scale factors as 40 for VNIR and 80 for SWIR. Which is correct
Also this information has to be contained in a ASCII file, is there a standard file for this or do I have to create it
Thanks for your help
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3 |
1579 |
14 Mar 2011 03:00 PM |
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1 Replies and 1436 Views
Problem with converting shp/evf file to ROI for supervised classification 1436 1
Started by Deleted User
Hi,
I am very new ENVI user. I have a problem with converting shp/evf file to ROI and can't figure out what might actually goes wrong. Suppose, I have a vector file containing 15 polygons (entries) as a set of training areas. Once I am trying to convert given vector file into ROI, it turns out only some entries are converted to ROI not all 15 are converted. I checked if there was something to do with mismatched coordinate or projection systems but everything was okay.
Please help ...
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1 |
1436 |
14 Mar 2011 10:45 AM |
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6 Replies and 1643 Views
ASTER stereoimages 1643 6
Started by Deleted User
HI
i want to generate DEM from ASTER stereo images but i got many negative values in my final DEM.IS there any one can help me to correct this and why the stereoimages show negative values for elevations
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6 |
1643 |
11 Mar 2011 08:19 PM |
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0 Replies and 1328 Views
Linear Unmixing 1328 0
Started by Deleted User
Hi, I've done linear unmixing on an urban Landsat TM scene and have split into three endmember components. I now want to know the proportion of each endmeber in the image. If I hover over a pixel it gives me the ratios for the pixel but I want the ratios for the whole image. Any ideas
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0 |
1328 |
10 Mar 2011 08:53 AM |
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1 Replies and 1874 Views
QUAC To reflectance 1874 1
Started by Deleted User
Hi everybody,
Currently i am trying to convert World view 2 data into reflectance using method available from envi. And Quac is giving me best result so far. However, reflectance value from the converted image is up 3000. I dont know what unit is it. Is there any method to rescale the data to convensional reflectance value of
Highly appreciate is someone can help me.
Thanks
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1 |
1874 |
07 Mar 2011 10:02 PM |
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3 Replies and 1136 Views
Stereo WorldView 2 1136 3
Started by Deleted User
We have stereoimagery from Worldview 2 which is not recognized as epipolar imagery by ENVI. Geoeye-1 stereoimagery was recognized by the DEM extraction module as epipolar imagery. Is there some modifcation we may make to the header information or some such so we do not have to build the epipolar imagery on the WorldView 2 data We are using ENVI 4.8.
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3 |
1136 |
05 Mar 2011 01:35 PM |
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1 Replies and 1558 Views
Sensor altitude hight 1558 1
Started by Deleted User
During atmospheric correction of hyperion data, one of the parameter asked is sensor altitude hight. can any one tell whether it is contant(705 km)for all region or vary from location to location.
Thanks
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1 |
1558 |
05 Mar 2011 07:50 AM |
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1 Replies and 1290 Views
Change default data range 1290 1
Started by Deleted User
Hi,
I have some data result calculated by Fortran, it's double precision in Fortran. And I can look at the data in EXCEL, but a lot of data change to 0 when I look at it with ENVI. I guess it's something with the default data range of ENVI, could you please give me some suggestions
Thanks a lot!
Steven
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1 |
1290 |
04 Mar 2011 10:12 AM |
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1 Replies and 2448 Views
scale factor file for FLAASH correction of Hyperion image 2448 1
Started by Deleted User
Hello,
I have a L1R Hyperion image that I am trying to atmospherically correct
using the FLAASH module in ENVI.
I understand that the L1R Hyperion data are in integer data type where
the VNIR and SWIR range bands have been rescaled by multiplying by 40
and 80, respectively. The units are W/m2*sr*micrometers
I read in the ENVI QUAC and FLAASH module that FLAASH requires the
input data in floating point data type with microW/cm2 * nm* sr.
My questions are:
1) Wh...
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1 |
2448 |
04 Mar 2011 08:41 AM |
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2 Replies and 2869 Views
How to rename image layers - or, keep Envi from doing so? 2869 2
Started by Deleted User
I'm stacking landsat imagery, then doing a few steps in Envi (4.5).
The problem is that Envi adds to the layer name each step, and then if I do a couple steps, by the time I export to .img format, the names are so long that they get truncated, and I lose the info I need (the band number!! but also the image date and my own simple code) in the result.
It's easy to rename image layers in Arc Catalog after the export, but often that's too late as there's nothing left of the original layer n...
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2 |
2869 |
03 Mar 2011 03:18 PM |
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1 Replies and 1363 Views
A problem with Principal Component transform with TM data 1363 1
Started by Deleted User
The remote sensing data was download from the website of NASA, and some of the data can perform the transform without problem, however, some of the ETM and TM file was failed to execute this transform, the error message is here.
"A error was caught in the main event handler. Error: unable to dereference NULL pointer:P_INFO"
Any help is appreciated!
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1 |
1363 |
24 Feb 2011 06:43 PM |
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1 Replies and 1515 Views
Reconcile ROIs via map in ENVI batch mode 1515 1
Started by Deleted User
Hi,
I'd like to know how I can extend the "reconcile ROIs via map" ENVI command, to ENVI batch mode. I'm trying to use ROIs, previously defined in one RGB image, to classify a new hyperspectral image... But I can't find the right ENVI routines.
Can you help me please
Thanks very much!
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1 |
1515 |
24 Feb 2011 07:32 AM |
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1 Replies and 1648 Views
coregistration 1648 1
Started by Deleted User
Hello,
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1 |
1648 |
22 Feb 2011 11:27 AM |
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1 Replies and 1427 Views
contours to DEM 1427 1
Started by Deleted User
Hi folks,
I've the contours in AutoCAD (.dxf) file and wish to create DEM. I first converted the .dxf into .evf and then used Topographic> Convert contours to DEM tool. But the system is not allowing me to change the DEM Output Parameters with ENVI Error “Attempt to call undefined procedure/function:’ENVI_GRID_PARAM_EVENT’.”
What should be done
I really appreciate your help.
Cheers,
Simit
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1 |
1427 |
21 Feb 2011 07:00 AM |
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1 Replies and 1278 Views
GCP display size 1278 1
Started by Deleted User
Is it possible to change the size of the displayed Ground Control Points on image during the map registration process
I am able to change the colour of the points (GCP selection>Option>set point colors) but couldn’t find an option for playing with the font size of the points.
Thanks.
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1 |
1278 |
20 Feb 2011 06:16 PM |
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0 Replies and 1241 Views
Visualization of Pixel Purity Index value for each pixel in a Histogram 1241 0
Started by Deleted User
Dear all,
I am a new user in ENVI user forum. Currently I am using ENVI PPI toolbox for Spectral Mixture Analysis of Landsat data. During wirk, I found that after getting the PPI value,if I choose the Histogram Stretching from PPI Image Window, the output histogram shows the PPI value with the total number of pixels having that PPI value. I want to get the PPI value for each pixel of the image in a histogram. It will be really appreciated if anyone can suggest me how do I get it. Waiting f...
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0 |
1241 |
17 Feb 2011 07:42 PM |
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2 Replies and 1133 Views
3D Lidar Viewer 1133 2
Started by Deleted User
Hi,
I would like to ask some questions about new 3D Lidar Viewer.
1) I am not able to open lot of files, that I was able to open in ENVI 4.7 with Lidar Toolkit - for example dataset, that are in folder LIDAR Visualisation - demo dataset that can be downloaded from ITT VIS pages (file 42124B3317.las) and also *.las data from LiDAR demo skript called las_sample_1. All these files I am able to open in ENVI 4.7 with Lidar Toolkit, but with ENVI 4.8 new LiDAR Viewer I have only black window o...
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2 |
1133 |
17 Feb 2011 12:50 AM |