Section 2: Loading Datasets

  • Datasets must be geo-located within Western Australia to be loaded.
  • Currently supported file formats:
    • Image (.ecw, .tif, .jpg)
    • Grids (.grd, .ers, .gxf)
    • MT datasets (ascii file with extension of .2MT or .rho)
    • 3D voxsets (ascii file with extension of .dat or .3ds) Note that MT and 3D ascii files are not recognised by ArcGIS, so can only be drag-and-dropped from Windows Explorer.
  • Datasets are loaded into IEP via drag-and-drop commands onto the dataset list (Figure 1 – Panel 1), from 3 possible sources:
    1. Directly from Windows Explorer (can drag multiple datasets simultaneously)
    2. From ArcCatalog (either ArcCatalog itself, or the Catalog side panel within ArcMap)
    3. From the Table of Contents in ArcMap
  • Image datasets dropped onto the list are loaded as-is, and data and colour stretch options are disabled; however images can also be treated as grids.
  • Grid datasets dropped onto the list are loaded with a default Histogram Equalised and Greyscale colour map for the data and colour stretch options respectively.
  • Multi-band Image and Grid datasets have an optional menu (Data bands) and dialog to determine how the dataset is treated, either as a single band of data, or as 3-band RGB converted into a single band (greyscale) of data.
  • Large Image and Grid datasets are recommended to be displayed with Pyramid texture tiles (accessible in the context menu), since a single texture representation of dataset may appear black if graphic-card-memory is depleted.
  • MT and 3D datasets dropped on the list are loaded with a default Linear Normalisation and Rainbow colour map for the data and colour stretch options respectively.

Steps

  1. Select a geophysical grid (preferably an .ers) from either the Catalog panel in ArcMap, or from Windows Explorer, and drag it onto the Raster Data list (Figure 2). It may take a few moments for the default rasterisation to complete.
  2. It may be necessary to click on the icon2 button to refocus the camera to the selected data item, especially if multiple items with different spatial references are loaded.
  3. Change the Colour option to a Rainbow colour map by right-clicking on the selected item in the data list, and accessing the context menu.
  4. Change the Data stretch to Linear Normalisation. It may take another few moments for the rasterisation process to complete.
  5. Now that both data stretches has been rasterised, results from a previous rasterisation process will be quick loaded on request. Switch between data stretches and choose the most appropriate stretch.
  6. Add further datasets of different types through drag-and-drop commands, and choose appropriate corresponding data stretch and colour options.
  7. Toggle the Pyramid texture tiles option to change the way the dataset is displayed. In tiles mode, zooming and panning the camera will trigger a reload of the appropriate tiles to display, and may need a moment to load.
  8. Re-add a previous geophysical grid, but now apply the Dynamic Range Compression filter [1]through the Run DRC … option in the context menu. Choose values for the minimum and maximum parameters of an appropriate feature size range in cells. Note this may take a few minutes, and the results are represented in the re-added item. Individual filter results can be displayed via the Display Filter param option.
Figure 2: Datasets can be loaded in the IEP by dragging datasets from the Catalog panel in ArcMap and dropping onto the IEP Raster Data list.

Figure 2: Datasets can be loaded in the IEP by dragging datasets from the Catalog panel in ArcMap and dropping onto the IEP Raster Data list.

[1] The DRC algorithm was developed to filter data with high dynamic ranges such as aeromagnetic images. The filter preserves the phase of the spatial frequency of the image while also compressing the range, which allows more easily interpreted images. The range of spatial frequencies can also be selected to enhance particular features of a certain size. See here for more information.