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1 Replies and 1343 Views
band math over a subset of an image? 1343 1
Started by Deleted User
I have a need to, in an IDL/ENVI function, perform band math on subregions of a (in this case, Landsat) image. I know this can be done by subsetting the image from the start, and performing band math on the subregions as separate images; however, I would much prefer to perform the bad math on each subregion while it is within the full image, if this is possible.. This would prevents my having to make a mosaic of the separate regions, later. Is this possible If it IS, I'd love to know how!
...
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1 |
1343 |
05 Oct 2011 03:57 PM |
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3 Replies and 1071 Views
Convert reflectance from 10000 (=100) to 1? 1071 3
Started by Deleted User
My hymap dataset is in reflectance. 10000 correspond with 100 . How is it possible to convert my data with a range from 0 to 1 in Envi
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3 |
1071 |
05 Oct 2011 09:04 AM |
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1 Replies and 894 Views
Neighbourhood Correlation Image 894 1
Started by Deleted User
Could you please help me in How to generate Correlation, Intercept and Slope images in ENVI 4.5.
Actually, I have two date TM images, each of three bands, and I want to see the changes between them using Correlation, Intercept and Slope images.
I got a reference for computations of three variables—correlation, slope, and intercept—from the correlation analysis were calculated using from Im and Jensen, 2005, Remote sensing of environment, 99, page 326-340
But I do no...
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1 |
894 |
04 Oct 2011 07:37 PM |
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1 Replies and 983 Views
image type transfer 983 1
Started by Deleted User
Hi all,
I have 7 bands ENVI Standard image with data value from 0.000000 to 1.000000. I want to save it as a tiff image with the original data value. When I select file-save image as-image file, it just has 8-bit gray, 8-bit color and 24-bit color options, the results just contain the value of RGB but miss the original values.
How could I solve this problem
Thanks,
Jie
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1 |
983 |
03 Oct 2011 09:42 AM |
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1 Replies and 867 Views
resampling 867 1
Started by Deleted User
My questions concerns resampling methods, which actually interpolate data: bilinear and cubic convolution. I feel a bit confused after reading Envi tutorials regarding these functionalities. Resampling changes the brightness values, yes, but the brightness values in, say, multispectral datasets are calculated from reflectance/data values. I just wanted to make sure that I understand the resampling process right. So in some cases the data values change when we use e.g. cubic convolution resamplin...
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1 |
867 |
02 Oct 2011 05:41 PM |
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0 Replies and 1052 Views
resampling 1052 0
Started by Deleted User
My questions concerns resampling methods, which actually interpolate data: bilinear and cubic convolution. I feel a bit confused after reading Envi tutorials regarding these functionalities. Resampling changes the brightness values, yes, but the brightness values in, say, multispectral datasets are calculated from reflectance/data values. I just wanted to make sure that I understand the resampling process right. So in some cases the data values change when we use e.g. cubic convolution resamplin...
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0 |
1052 |
02 Oct 2011 05:40 PM |
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1 Replies and 1331 Views
Atmospheric Correction 1331 1
Started by Deleted User
I have a student licence of ENVI and im trying to run an atmospheric correction algorithm:
1) If i attempt to use the FLAASH algorithm, i get a message that I have to open ENVI in 32-bit mode. I dont know how to do this.
2) If i attempt to use the Quick algorith, I get a message that i do not have a licence to the atmospheric correction modules. Is this not included in the student licence
3) After performing an atmospheric correction, is it possible to extract the spectra...
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1 |
1331 |
28 Sep 2011 06:21 PM |
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1 Replies and 2015 Views
What is the sensor azimuth and zenith for landsat 7? 2015 1
Started by Deleted User
Hi, I'm executing FLAASH on my landsat-7 imagery. I'm getting a lot of negative values in the output image, which is obviously wrong. I'm using the default sensor azimuth and zenith angles, which I'm not sure about. Does anyone know where can I obtain this information Or is the Landsat-7 sensor a nadir viewing sensor
Thanks in advance
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1 |
2015 |
28 Sep 2011 03:02 PM |
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2 Replies and 1299 Views
floating license - reserving usage with options file 1299 2
Started by Deleted User
Hello,
In the "Installation_and_licensing_Guide.pdf" there's an option explained that let's one create and options file (idl_lmgrd.opt) in order to manage license usage. There's an example using the 'reserve' keyword to reserve licenses to specific users or groups, but is it at all possible to reserve a particular number of licenses to certain machines no matter who the user is And on top of that, can the access be time restricted
My scenario is that I want to reserve l...
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2 |
1299 |
28 Sep 2011 02:04 PM |
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0 Replies and 1563 Views
SARscape tutorials? 1563 0
Started by Deleted User
Anybody know where I can get SARscape tutorials like they show here:
http://www.ittvis.com/language/en-us/productsservices/envi/tutorials.aspx
These are great tutorials and I've learned a lot using them. However, the next phase of my research requires that I do InSAR processing and therefore I need the SARscape tutorials.
I see the "Radar and Topographic Tools" under the EVNI tutorial link above which appears to be related to SARscape but I don't believe it actua...
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0 |
1563 |
27 Sep 2011 12:49 PM |
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1 Replies and 1176 Views
Export ENVI to ArcMap but retains reflectance values 1176 1
Started by Deleted User
I would like to ask how can i possibly export an ENVI image to arcmap but retains its reflectance values When i tried to export it to arcmap, the values becan an 8-bit (0-255 values). Thanks.
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1 |
1176 |
23 Sep 2011 08:56 AM |
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1 Replies and 1011 Views
Alligning 2 image layers 1011 1
Started by Deleted User
Hi All,
I'm trying to produce an image stack of hyper-spectral bands and LiDAR derived rasters. I have data sets from the specim eagle (both for winter and summer conditions and 200 image bands each) and LiDAR canopy height models all at 1m resolution.
I have an issue with one of my hyper-spectral data sets (summer eagle), in that the features don't quite line up with the other hyper-spectral and LiDAR layers. The image may be 2-3 meters off in the horizontal and vertical for the entire ...
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1 |
1011 |
22 Sep 2011 01:51 PM |
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1 Replies and 1199 Views
Making attribute map in ENVI plus conversion of vector map to raster 1199 1
Started by Deleted User
Dear all
I tried to produce an attribute map in Envi 4.5 from the shape file imported from ArcGIS but to no avail. The other issue is pertaining to exporting vector to raster format in ENVI environment (Other than ROI). Is it possible and the final query is what file format (excluding satellite images) does ENVI support to carry out supervise classification. The reason being that when I tried ESRI grid format (1 band), the message pops up....more than 1 band required. My intention is to...
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1 |
1199 |
16 Sep 2011 03:08 AM |
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17 Replies and 3141 Views
FLAASH Scale Factor and Radiance Units 3141 17
Started by Deleted User
Hello, I am a relatively new ENVI user and I am trying to use the FLAASH module on Worldview 2 data. What I have done so far is convert the Worldview 2 data from raw DN to radiance using the built-in Worldview 2 radiance calibration tool. The metadata says the data is now in units of: MicroWatts/(square centimeter *steradian * nanometer) and values in the images range approximately from 0 to 65397. The data type information for the data is: BIL, unsigned integer, with byte order host (intel). If...
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17 |
3141 |
13 Sep 2011 05:19 PM |
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1 Replies and 1053 Views
Selecting active display in software 1053 1
Started by Deleted User
I want to give users of my ENVI tool the ability to select, from a list of existing displays, where they want the processing result to show up, i.e.
get the list of existing displays via envi_get_display_numbers
get the user's choice of display via widget interface
make the selected display the active display
send the processing result to the active display via envi_display_bands
I can find no ENVI routine that sets the active display (step 3 above). I've tried calling...
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1 |
1053 |
13 Sep 2011 09:47 AM |
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1 Replies and 1027 Views
IKONOS image trouble 1027 1
Started by Deleted User
An IKONOS image I just got doesn't match my GPS points even though I have changed the projections to match.
Are there any ideas as to what else I should check or try
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1 |
1027 |
12 Sep 2011 10:49 PM |
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4 Replies and 1063 Views
Help with displaying vector overlay points loaded from ascii file 1063 4
Started by Deleted User
Hello, I need some help with displaying vector overlays on an image.
I have an ascii file with 1000 random x,y points which I have loaded via the overlay->vector function.
Example of the file is:-
X Y
6020 5402 1
6282 4255 2
6048 4732 3
5855 2704 4
5670 5169 5
with the last column being a point number.
The file appears to load OK. I can create the .dbf file which contains the full list, but I cannot see any of the vectors(points) showing in the image.
Would anyone know a so...
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4 |
1063 |
12 Sep 2011 07:23 PM |
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5 Replies and 1297 Views
subsetting landsat image from an EVF or ROI file programmatically 1297 5
Started by Deleted User
Hi folks - It seems there ought to be an easy way to do the task I need to do in programming space.
I want to write some code that can read in a series of Landsat images and subset them to an .evf file and save them subsetted. There does not appear to be an ENVI_DOIT sort of command that can do this, am I correct What is the easiest way to program what I want to do
thank you,
Cyndy
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5 |
1297 |
12 Sep 2011 11:16 AM |
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2 Replies and 1081 Views
mirror GeoTIFF image display 1081 2
Started by Deleted User
Hello,
i have a question regarding GeoTIFF format image display in ENVI (4.8). I wanted to subset my aerial HR image but when i opened it this image is mirrored. Can you please suggest me what i should do to get correct display of an image since i need it for further analyses And why ENVI displays it like this Thanks in advance!
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2 |
1081 |
09 Sep 2011 08:18 AM |
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1 Replies and 929 Views
DEM from Cartosat 929 1
Started by Deleted User
I used Cartosat for extracting DEM but the final DEM has inverted heights i.e ridge appears as valley and vice versa. That is probably due to interchange of left and right stereoscopic image pair in the input dialog box. It took 4 hours for my PC to process the DEM. So i wanted to know if there is any solution to fix this without going through the whole extraction process. Also i wanted to register the DEM heights from float values to meters.
I am beginner so please bear with me.
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1 |
929 |
07 Sep 2011 07:41 AM |