Opening large hyperspectral images - NV5 Geospatial

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Last Post 04 Feb 2020 09:08 AM by Paul Manley

Opening large hyperspectral images

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Emmanuel Gonzalez

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03 Feb 2020 01:23 PM
I am trying to load large (24 gb) hyperspectral images into ENVI but am not having any luck. When I select the file to open, the program goes to "not responding" and the spinning loading wheel just keeps going and eventually we just terminate the program after waiting for hours. I am loading them as binary files. The images are from a Headwall VNIR camera. The data file itself does not have a file extension (for example, we are trying to load the file called "2a7ed5fd-1c14-472d-94b6-d65fca62086c_raw"). We have been able to load these types of files when they are smaller (2 gb) using ENVI so we are a little perplexed on what the issue could be. I do not think its a hardware issue because when we watch the system performance when ENVI is trying to open the file, it never exceeds 8 gb of used RAM. With ~245 gb of RAM available I don't think this should be the limiting factor. We are clearly missing something basic, could anyone help me out with this?? Thanks! Envi version: 5.5, 64-bit Windows 10 256 gb RAM

MariM

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03 Feb 2020 02:41 PM
My guess is that it is building the pyramid file (with the .enp extension) and it is taking a very long time. These files make the performance better for zooming in ENVI. but they can take a while to load. Do you know the interleave of your data? Is it BIP? I have noticed that BIP can be less performant than BSQ or BIL. You said it is binary but does that mean it is has a .hdr file which is the ENVI format? Can you launch ENVI classic and open it? If so, my guess is that it is building the pyramid file.

Paul Manley

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04 Feb 2020 09:08 AM
Hello Emmanuel, I have the Headwall Nano-Hyperspec and deal with files of a similar or larger size. Mari is right, it's trying to pyramid the file and create the .enp. Because of my IDL needs, I change all the file extensions from no extension to .dat (for the image file, not the .hdr file). I don't think that should matter for just loading it in, just giving you more info than you need. I also started working off of the same drive. Is the data you're trying to load on a secondary drive? ENVI doesn't play well with reading/writing to a different drive, at least for files that are so large. I only have 32 GB of RAM and have no issues using our mosaics when on the same drive. The main drive in this computer is a HDD and the secondary is an SSD, so I thought that would be beneficial, but it was not.

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