AVIRIS-5 Reflectance Raster Georeferencing

[poojasheevam]

Hello!
I recently posted about assigning locations or georeferencing for the reflectance rasters and was not given anything that answered my issue. The github page did not help resolve the issue of geolocations on reflectance rasters. I included images that may help understand what is going on. Currently, you can only see lat/lon values on only radiance and observed rasters, but not on the reflectance rasters. Even after following the correct steps on the github, and taking some suggestions of saving files to ENVI format, there is no way to add spatial reference in any of the ENVI tools or in the metadata editor. I have tried manually editing the metadata and some orthorectification with a reference raster. I have also tried ENVI tools such as The only other way is to create ground control points comparing the two rasters - but that generates an ENVI error stating that the Reflectance raster needs some form of a georefernce (which it does not have...)
Now lets say I don't do the ground control points and just analyze the image by creating ROIs. Those ROIs do not translate into the radiance raster because there is no lat-lon data associated with pixels in the reflectance raster. Not to mention that the images are oriented differently (one verticle, one horizontal), and the RDN image is not orthocorrected, so I could not match ROI based on ENVI generated x , y points.
So I hope that this clarifies what the issue is with the AVIRIS -5 reflectance data and how this poses an issue to image processing.

[piyush]

This data is already orthorectified in netCDF files and uses CF conventions. So try using an appropriate netcdf reader

Code: Select all

⇒  gdalinfo NETCDF:"AV520250627t181139_006_L2A_OE_25ef84e2_RFL_ORT.nc":/reflectance/reflectance | more
Warning 1: dimension #0 (wavelength) is not a Time or Vertical dimension.
Driver: netCDF/Network Common Data Format
Files: AV520250627t181139_006_L2A_OE_25ef84e2_RFL_ORT.nc
Size is 2203, 2431
Coordinate System is:
PROJCRS["WGS 84 / UTM zone 11N",
    BASEGEOGCRS["WGS 84",
        DATUM["World Geodetic System 1984",
            ELLIPSOID["WGS 84",6378137,298.257223563,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        ID["EPSG",4326]],
    CONVERSION["UTM zone 11N",
        METHOD["Transverse Mercator",
            ID["EPSG",9807]],
        PARAMETER["Latitude of natural origin",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8801]],
        PARAMETER["Longitude of natural origin",-117,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8802]],
        PARAMETER["Scale factor at natural origin",0.9996,
            SCALEUNIT["unity",1],
            ID["EPSG",8805]],
        PARAMETER["False easting",500000,
            LENGTHUNIT["metre",1],
            ID["EPSG",8806]],
        PARAMETER["False northing",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8807]]],
    CS[Cartesian,2],
        AXIS["easting",east,
            ORDER[1],
            LENGTHUNIT["metre",1]],
        AXIS["northing",north,
            ORDER[2],
            LENGTHUNIT["metre",1]],
    ID["EPSG",32611]]
Data axis to CRS axis mapping: 1,2
Origin = (468922.957748158019967,4167998.811341709922999)
Pixel Size = (10.600000000000000,-10.600000000000000)
Metadata:
  /reflectance/reflectance#grid_mapping=transverse_mercator
  /reflectance/reflectance#long_name=Surface hemispherical directional refle
ctance factor
....

[poojasheevam]

Hi Piyush,
I think you misunderstand the issue. Yes the data is Orthorectified, and ENVI is able to import NetCDF files just fine. What is happening is that the pixels in the Reflectance image do not have lat-lon values associated with them.
There is no way to do it when editing the metadata because what you will get is an error in ENVI saying "dataset name or template must be provided”. There is no way to utilize the ground control points tool in ENVI to directly pull lat lon values with pixels because the error generated is that the input raster must have a RPC spatial reference.

The answer you have provided does not help resolve the issue.

[piyush]

This appears to be a limitation of the tools you are using. As shown above, the geotransform is available in the data and easily accessible via most open source tooling. The data is on a regular UTM grid and maybe your specific toolset is too limited to be able to work with it or it is being used incorrectly. You do not need RPCs as the data is already orthorectified.

[rupeshornl]

Hi @poojasheevam and @piyush, Phil Brodrick from JPL pointed out that `SpectralUtil` tool can convert AVIRIS-5 netCDF file to ENVI format correctly. We have updated the tutorial accordingly: https://ornldaac.github.io/airborne/notebooks/aviris/aviris-5-l2a-envi/