Jump to content
PDS Geosciences Node Community

Search the Community

Showing results for tags 'geomorphology'.

  • Search By Tags

    Type tags separated by commas.
  • Search By Author

Content Type


Forums

  • PDS Geosciences Node
    • Announcements
    • For data providers
    • For data users
  • PDS Geo Tools
    • Analyst's Notebook
    • ODE - Orbital Data Explorer
    • Spectral Library
    • Virtual Astronaut
  • Workshops
    • MRO/CRISM Data Users' Workshop 2012

Categories

  • Data user tools

Blogs

  • Working with PDS data
  • Using the Analyst's Notebook

Find results in...

Find results that contain...


Date Created

  • Start

    End


Last Updated

  • Start

    End


Filter by number of...

Joined

  • Start

    End


Group


Location


Interests

Found 1 result

  1. Hello, I'm trying to locate mineral clusters in CRISM I/F data using a Self-Organizing Map, but ultimately, even though I normalize the data prior to running a SOM my output clusters correspond with bright and dark areas. I am working with GRASS and R, so here are my processing steps: - import CRISM data into R, each pixel contains a vector of 254 values corresponding to the I/F values in the first 254 image bands. I am now working with a matrix, of n rows (number of pixels in image) by 254. This CRISM data has previously been though the CAT pre-preprocessing pipeline. - Calculate the mean value of each pixel, so that each pixel is now a residual vector (difference of each band from the mean spectrum of the pixel) - This means that I can better compare pixels to one another, as they are not affected by differences in brightness (are not offset from one another, as they would be if I used the mean spectrum of the image). - normalize each vector component [0,1] - use this new residual matrix as input into a 50x50 SOM. - The output codebook data from the SOM I simply classify with hierarchical clustering (for the moment) so I can see basic separable regions. (This basic number of clusters I estimate using a distance/similarity matrix.) Unfortunately, despite the above steps these clusters still correspond to bright/shadowed areas, in the majority of cases. I was hoping someone might be able to offer some suggestions as to why this might be?
×
×
  • Create New...