| 19 May 2010 01:46 PM |
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Hello,
I conducted a vegetation delineation on a 1m pansharpened IKONOS image. It generated a "classification" image with four classes (no veg, sparse veg, moderate veg and dense vegetation). I modified the NDVI values to fit more closely what I see in the true color image.
I would like to know if there is any way to generate a stratified random sample of points using these four "classes"? I have generated a random sample of points for an unsupervised classification that I conducted on the same 1m pansharpened IKONOS image. However, I cannot do the same steps for the image generated trough the vegetation delineation because it is a multi spectral image and not a classification image.
Does somebody know what I need to do to convert the multi spectral image to a classification image or vector files? so I can conduct a stratified random sample.
Thank you
Colibri
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MariM
Veteran Member
Posts:2396  
| 19 May 2010 02:13 PM |
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During Vegetation Delineation, you have the option to export the ROIs used to delineate the classes. If you do this, you could use the NDVI and these ROIs to generate a stratified random sample using Basic Tools ->Statistics ->Generate Random Sample ->Using Ground Truth ROIs. This option may work for you.
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Deleted User
New Member
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| 19 May 2010 03:05 PM |
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Hello, I don't actually see the option of exporting the ROI's used to delineate the classes. I tried choosing the change graphic overlay selections to display ROI but nothing comes out. What am i missing?
thank you
Colibri
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MariM
Veteran Member
Posts:2396
| 19 May 2010 03:11 PM |
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I assume you are running the Vegetation Delineation from the SPEAR Tools, yes? After the NDVI is calculated and where it shows the 'No Veg', 'Sparse Veg', etc classes, there is a button below this to 'Export to ROIs'. This is what I used.
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Deleted User
New Member
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| 19 May 2010 03:19 PM |
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Yes that is what I am using. But all I see below the No Veg', 'Sparse Veg', etc classes is three buttons: Ld image, restore defaults and save to file.
C
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MariM
Veteran Member
Posts:2396
| 19 May 2010 03:23 PM |
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What version of ENVI are you using? The option to save out ROIs was added to this tool in ENVI 4.6 and I am using ENVI 4.7. In this case, you can apply a Density Slice manually via Tools ->Color mapping ->Density Slice. Set up the same ranges as in the Veg Delination tool and export the ranges to EVF. The EVF files can be exported to ROIs which can then be used in the random sample generation.
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Deleted User
New Member
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| 19 May 2010 03:24 PM |
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Sweet I wil try that. I am using 4.5. You are a great help
Colibri
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