In Geosoft desktop software (Oasis montaj, Target or Target for ArcGIS) the term "grid" usually refers to a raster dataset. A grid (.grd) is a data product created from a point dataset that has been 'gridded' (interpolated) to create a raster. For example, a magnetic survey dataset is collected as a series of point values, organized into a number of lines. When interpolated to create a raster containing pixels of equal size, we call this a 'grid'.
Grids or rasters usually represent datasets collected on, above, or in some cases below, the earth's surface. Geosoft grids have two important companion files, the "grid information" GI file and an XML metadata file.
Most of the grids we encounter are located on, or at a fixed height above, ground level. Some grids are located beneath the ground (such as a grid of depth values to a local water table, or lithology unit). Other grids can be oriented vertically, or at an angle to the vertical, to represent data that varies laterally in the subsurface.
When converting section oriented grids (i.e. vertical or inclined rasters) that have been georeferenced (or 'oriented') in Geosoft software, the 3D location and orientation will be maintained during the conversion, provided the GI file is present. These section oriented rasters must have been originally oriented in a Geosoft software such as Oasis montaj, Target or Target for ArcGIS.
On conversion, a section oriented raster will be converted into two objects: a multipatch feature class that contains the outline of the section raster location, and a raster dataset that contains an image of the original raster data. By displaying these two datasets together in 3D, the original location, orientation and appearance of the section raster is maintained.
Note that, if the active map pane in ArcGIS Pro is a 3D scene, the section raster datasets will automatically appear at their correct location and orientations in the scene. If the active pane is a map window, section oriented rasters will appear as a polygon outline of the raster location only (the multipatch outline). To view section rasters correctly, add them to a 3D scene.
Viewing raster datasets consistently in different software programs can be challenging, as recreating the same symbology options (color ramps and stretch types) can be difficult. When converting Geosoft grids to Esri raster datasets, the last used color symbology is extracted from the GI file, and applied to the new raster layer in ArcGIS Pro, so the converted raster will look identical to the original grid.
When viewing grids in Geosoft software, certain raster appearance defaults are often used, such as the Geosoft standard color ramp (colour.tbl) and the histogram equalized color stretch (the default stretch type used in Geosoft). These can be applied to any raster dataset in ArcGIS Pro by using two of the tools provided on the Target ribbon: Import Geosoft Colors and Equalized Histogram color symbology.
Section grids are often imported as a set or group of files, rather than single rasters. Often but not always, a group of section rasters will have a predefined color scheme - one that represents the full range of data values in all grids. This means that when viewing a set of sections together, the colors on each section grid should represent the same data value. Also note that neither the ArcGIS Pro raster symbology tools, nor the Add-In Quick Appearance tools can be used to re-color section rasters.
Geosoft software stores all the spatial reference and coordinate system information as well as any associated symbology for a grid (.grd) file in an associated GI (.gi) file. For example, the grid file "mygrid.grd" would have an associated grid information file named "mygrid.grd.gi". The last displayed symbology is also stored within the GI file.
When copying a grid file to another directory or when sharing a grid file with others, you must include any existing GI (.gi) files associated with the grid file in order to maintain the units and coordinate system information for the grid. Without the original GI file, a grid file can appear in the incorrect location and/or orientation.
Geosoft software stores all the metadata for a grid (.grd) file in an associated XML (.xml) file. For example, the grid file "mygrid.grd" would have an associated XML file named "mygrid.grd.xml".
When copying a grid file to another directory or when sharing a grid file with others, you should include any existing metadata (.xml) files associated with the grid file in order to maintain the metadata information for the grid. The XML file is not necessary for the correct location of the grid.
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