CMS-Flow:Grid Generation

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Steps for Preprocessing Elevation Data

  1. Select the project horizontal and vertical datums and projections
  2. If necessary, convert bathymetric/topographic input files to the correct projection and datums
  3. If necessary, thin the input scatter sets so that they are more manageable to work with. This is especially important for dense data like LIDAR or mulibeam data. There are several ways of thinning the data, such as binning, merging nearby points, skipping points or using a critical slope. Keep all of the input files to less than a few hundred megabytes.
  4. Checking data set coverages
    1. Bring each bathymetric/topographic data set into SMS
    2. If two data sets overlap make sure that the data sets match in the overlapping region. In many cases, they will not. If they do not match, select the data set taken closer to the simulation period or if both are from a similar time period, than select the more reliable dataset (usually the more dense also).
    3. Delete the correct data set in the overlapping regions
  5. Outlier removal
    1. If available, bring in aerial photographs or satellite images into SMS. This is very helpful for orienting and determining outlier points.
    2. Zoom-in to an individual data set
    3. Set the contour color scheme for the scatter set to a narrow range so that outliers can easily be spotted.
    4. Delete outlier points
  6. Save individual data sets with a different name
  7. Merge the processed input files into a single data set and save into a separate file.

Telescoping Grid Generation

  1. Telescoping Grid Generation [PDF]

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