Creating a "virtual stacked" image - NV5 Geospatial

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Last Post 13 Feb 2012 08:41 PM by anon

Creating a "virtual stacked" image

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anon

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13 Feb 2012 08:41 PM
Greetings, As some of you know, I work with time-series data and have even written a couple of tools for this purpose with my somewhat limited IDL skills. One issue I have with my processing is that I spend a lot of time stacking data, as I need to sometimes update the image stacks once a month or every two weeks. This approach uses up a lot of time and twice the storage space as necessary. I have noticed that ENVI can stack imagery without actually having to write to the disk, as evidenced with Landsat GeoTIFFs, and the process is quite fast. Does anyone know how I could do this with multiple one-band GeoTIFFs or ENVI image files?

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14 Feb 2012 12:15 AM
You can use ENVI menu option FILE > Save file as > Envi Meta Then import the required files, stack them and save as Envi Meta file. The Envi Meta file is a kind of virtual stack where only path to inputs files with bands is stored and no new disk space is used. The Envi Meta file will not work in a situation where change of path of input files takes place. For any change in input file path - you have to recreate the Meta file or edit it manually in a text editor. Vinay

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14 Feb 2012 01:07 PM
Vinay, Thank you for your help- I have succeeded in making a small virtual stack. One thing my current stacking function does is convert year and Julian day to "wavelengths" so I can use these data for meaningful temporal analysis. Do you know if ENVI Meta files can work with external headers? If not then I can just add that wavelength information manually or using a script into the files' headers (for ENVI Standard files in the stack). Best regards, Guy

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