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Section: MB-System 5.0 (1)
Updated: 16 August 2013
Index
NAME
MBgrdviz - Simple interactive 2D/3D visualization of GMT grids.VERSION
Version 5.0SYNOPSIS
MBgrdviz [-Igridfile -T -V -H]DESCRIPTION
Overview
MBgrdviz is an interactive 2D/3D visualization tool for GMT topography grid files. MBgrdviz can be used for general data visualization and also has features integrating it with swath mapping data processing and swath survey planning.
Once a topographic grid has been read, it may be displayed either as a 2D map or as a 3D model. The 2D view can be panned and zoomed; the 3D view also allows arbitrary rotations of both the topography model and the viewpoint.
In addition to the primary topography, other data sets (e.g. sidescan sonar mosaics) can be read and displayed as overlays on the topography. Navigation of ships or underwater vehicles can be read and displayed; if associated with swath data the extent of mapping coverage can be displayed. Site data (individual point locations) can be read, displayed, interactively created and modified, and saved. Route data (collections of waypoints) can also be read, displayed, interactively created and modified, and saved.
The topography data can be shown using a number of colortables. The colortables can be linearly stretched between minimum and maximum values, or applied using a histogram equalization. The display may also be shaded using an illumination model, slope magnitude, or overlay grid data. Overlay data can be displayed draped on the topography. Topographic contours can be displayed using a user defined contour interval.
In addition to modifying the view, users can interact with the display in several ways. Users can pick single points on the surface to determine position and topography values, or pick and drag to determine range and bearing between two locations. Arbitrary rectangular regions with north-south and east-west boundaries or arbitrarily oriented rectangular areas can be defined by picking and dragging. The data within a region can be opened as a new display; areas can be used for survey planning.
Topographic profiles associated with two-point picks, selected navigation, or selected routes can be displayed in a separate window and saved.
MBgrdviz can be used to select swath data files for editing or analysis using other MB-System tools. If survey navigation has been read and displayed, a user may interactively select files of interest, and then start up the interactive waterfall bathymetry editor MBedit to work on those files. Also available are the interactive, visualization based bathymetry editor MBeditviz, the navigation editor MBnavedit, and the water sound speed modeling tool MBvelocitytool.
MBgrdviz supports as many as ten displays deriving either from reading topography grids or extracting user defined regions from existing displays.
Starting Up
When MBgrdviz is invoked on the command line, a single window comes up with the title MBgrdviz and two menus: File and Help. The Help menu contains a single item named About, which brings up a simple information window including the MB-System release version identifier. The File menu contains several items, but initially only the Open Primary Grid and Quit items are enabled. Selecting Open Primary Grid brings up a filesystem browser window that allows users to find and select the desired GMT topography grid. By default, the browser filter is set to display only files ending with a ".grd" suffix. Users can change this filter (e.g. setting it to "*" will display all files) and then hit the Filter button to relist the files as desired. Once the desired topography grid file has been located and selected so that its full path appears in the Selection text item, clicking the OK button will cause MBgrdviz to read the grid and open an MBview display window. Initially, the topography will be displayed in 2D, or map view mode. The default color table will be "Haxby", and the topography will be shaded using slope magnitude.
Picking, Zooming, Panning in 2D View
MBgrdviz will initially be in the "pan and zoom" mouse mode.
In this mode, if the cursor is over topography when the left button is clicked, a red X will appear at the pick point and an info window on the left side of the MBview display window will show the longitude, latitude, and topography value of the pick point. If the left button is used to drag the cursor from one location to another, both the pick and release points will be shown as red Xs and a red line will be displayed in between. The info window will show both the start and end positions and also the range and bearing between the two locations.
The middle button can be used to pan by clicking, holding down, and moving the cursor.
The right button can be used to zoom the display by clicking, holding down, and moving the cursor up to zoom in or down to zoom out.
Manipulating a 3D View
The user can switch from 2D map view to 3D view mode using the <View->3D Display> menu item (and can switch back using the<View->Map Display> menu item). In the 3D view mode, picking, panning, and zooming are done in the same fashion as in the map view. However, the display is a perspective view that includes both rotation of the topographic model and of the viewpoint. To rotate the model, select the "Rotate Model" button (or the <Mouse->Rotate Model> menu item). The left button can be used to pick topography, the middle button will rotate the model when clicked and dragged, and the right button will change the vertical exageration when clicked and moved up (more exageration) or down (less exageration). To rotate the viewpoint, select the "Rotate View" button (or the <Mouse->Rotate View> menu item). The left button can be used to pick topography, the middle button will rotate the model when clicked and dragged, and the right button will change the vertical exageration when clicked and moved up (more exageration) or down (less exageration).
AUTHORSHIP
David W. Caress (caress@mbari.org)
Monterey Bay Aquarium Research Institute
Dale N. Chayes (dale@ldeo.columbia.edu)
Lamont-Doherty Earth ObservatoryOPTIONS
Last Updated: 16 August 2013