This section describes the Overlay Control Center dialog (pictured below). This dialog serves as the central control center handling all currently loaded data sets (overlays).
This is a list of the all currently opened overlays. You can select an overlay by clicking on its name. Multiple overlays can be selected using the shift and control keys while clicking on overlays in the list. If the overlay is currently hidden, it is indicated to the left of the overlay description.
You can right click on the list of currently opened overlays to display a list of options available to perform on the selected overlays. Examples of available options include the following:
Selecting the Create Elevation Grid from 3D Vector Data option on the popup menu that appears when right-clicking on vector layers in the Overlay Control Center displays the Elevation Grid Creation Options dialog, pictured below. Using this dialog, you can configure how you want the elevation grid to be created using the selected vector data as well as what portion of the selected overlays to use when creating the elevation grid. You can also use the Gridding tab to specify that your data should be gridded in sections. This makes it possible to grid data sets that are too large to grid all at once.
Pressing the Metadata... button displays metadata for the selected overlay. The actual metadata dialog displayed depends on the type of the selected overlay. The metadata dialog for a SDTS DLG is shown below.
Pressing the Options... button displays a dialog containing the available display options for the selected overlay(s). Options can be set on multiple raster or elevation overlays at the same time. The available display options depend on the type of the selected overlays. The following display options are used:
Selecting the Options... button while an ESRI Shapefile overlay is selected displays the Shapefile Options dialog (pictured below).
The Feature Types tab provides the ability to specify which attribute field (if any) to display as the name of features loaded from the Shapefile. You can also specify the feature type to assign to features loaded from the Shapefile.
The Projection tab is used to reinterpret the raw vector data to a new projection. This is useful if the wrong projection was selected for the dataset when it was loaded, or if the data set itself indicated some incorrect data. This option is rarely used.
Selecting the Options... button while a vector (i.e. DLG, DXF, E00, etc) overlay is selected displays the Vector Options dialog (pictured below). This dialog is used to reinterpret the raw vector data to a new projection. This is useful if the wrong projection was selected for the dataset when it was loaded, or if the data set itself indicated some incorrect data. This option is rarely used.
For many vector formats, you will also see a Feature Types tab (pictured below), which will allow you to select what Global Mapper classification to assign to the unclassified area, line, and point features in the layer.
Selecting the Options... button while only raster (i.e. DRG, DOQ, MrSID, etc) overlays are selected displays the Raster Options dialog (pictured below).
The Color Intensity setting controls whether displayed pixels are lightened or darkened before being displayed. It may be useful to lighten or darken raster overlays in order to see overlaying vector data clearly.
The Translucency setting controls to what degree you can see through the overlay to overlays underneat the overlay. The default setting of Opaque means that you cannot see through the overlay at all. Settings closer to Transparent make the overlay increasingly more see-through, allowing you to blend overlapping data.
The Blend Mode setting controls how an overlay is blended with underlying overlays, in addition to the Translucency setting. These settings allow Photoshop-style filters to be applied to overlays, resulting in often stunning results. What you get from a particular set of overlays from a particular blend mode setting can often be hard to predict, so rather than try to understand what is technically happening for each blend mode it's best to just experiment with different ones until you find one that you like. The Hard Light setting seems to work well with satellite imagery overlaid on DEMs, but the others can be quite useful as well. For example, the Apply Color setting is useful for applying color to a grayscale overlay, such as using a low-resolution color LANDSAT image to colorize a high-resolution grayscale satellite image.
The Transparent option allows a particular color to be displayed transparently, making it possible to see through a layer to the layers underneath. For example, when viewing a DRG on top of a DOQ, making the white in the DRG transparent makes it possible to see much of the DOQ underneath. Pressing the Set Transparent Color... button allows the user to select the color to treat as transparent in the selected overlay.
The Anti-Alias Pixels (Interpolate) option removes jagged edges by making a subtle transition between pixels. Turning off this option helps maintain the hard edges of the pixels as they are rasterized.
The Texture Map option allows a 2D raster overlay to be draped over loaded 3D elevation overlays. Selecting the check box causes the overlay to use any available data from underlying elevation layers to determine how to color the DRG or DOQ. The result is a shaded relief map.
The Auto-Clip Collar is used to automatically remove the collar from loaded raster data. Most frequently it is used to removes the white border around a DRG or the small black collar around a 3.75 minute DOQQ. This allows you to seamlessly view a collection of adjacent DRG or DOQQ files.
For those cases in which you wish to modify the collar that the Auto-Clip Collar option removes from overlays, the collar bounds can be customized by pressing the Customize... button. Doing this displays the Customize Collar Bounds dialog (pictured below) which allows the user customize the lat/lon boundaries along which the collar runs.
The Auto Adjust Contrast option is used to automatically apply a two standard deviation contrast adjust to each color channel in the image. This is particularly useful for improving the display of dark or satellite imagery, such as IKONOS images.
Selecting the Options... button while only elevation (i.e. DEM, GLOBE, etc) overlays are selected displays the Elevation Options dialog (pictured below).
The Color Intensity setting controls whether displayed pixels are lightened or darkened before being displayed. It may be useful to lighten or darken raster overlays in order to see overlaying vector data clearly.
The Translucency setting controls to what degree you can see through the overlay to overlays underneat the overlay. The default setting of Opaque means that you cannot see through the overlay at all. Settings closer to Transparent make the overlay increasingly more see-through, allowing you to blend overlapping data.
The Blend Mode setting controls how an overlay is blended with underlying overlays, in addition to the Translucency setting. These settings allow Photoshop-style filters to be applied to overlays, resulting in often stunning results. What you get from a particular set of overlays from a particular blend mode setting can often be hard to predict, so rather than try to understand what is technically happening for each blend mode it's best to just experiment with different ones until you find one that you like. The Hard Light setting seems to work well with satellite imagery overlaid on DEMs, but the others can be quite useful as well.
The Transparent option allows a particular color to be displayed transparently, making it possible to see through a layer to the layers underneath. For example, when viewing a DRG on top of a DOQ, making the white in the DRG transparent makes it possible to see much of the DOQ underneath. Pressing the Set Transparent Color... button allows the user to select the color to treat as transparent in the selected overlay.
The Anti-Alias Pixels (Interpolate) option removes jagged edges by making a subtle transition between pixels. Turning off this option helps maintain the hard edges of the pixels as they are rasterized.
Pressing the Adjust Elevation Values/Units display the Alter Elevation Values dialog (pictured below). This dialog allows you to modify how elevation values from the selected layer(s) are interpreted, providing you a means to offset all of the elevations in the layer(s) by a given value and to restrict the range of elevation values that are treated as valid.
The Shader option allows you to choose which elevation shader is to be used for coloring the cell values within this layer. By default, all gridded layers will share the elevation shader selected on the toolbar, but there may be certain situations where you want to color one layer differently than the others and exclude it from the loaded elevation range. One common example is a gridded layer that actually has non-elevation data.
Toggles whether the currently selected overlays are visible.
Closes all the currently selected overlays.