Viewer

Description

A replacement for the ivview Inventor file viewing program that comes with the Inventor toolkit. Viewer has a number of features not available in ivview, which are designed to improve the visualization of meshes:

• white background - the background is white, which saves toner when including mesh screenshots in papers. White meshes are changed to a different color (green by default).
• grid lines - an evenly spaced grid is orthogonally projected onto the scene. The lines improve depth perception of feature-poor surfaces such as terrain.
• color contours - the mesh can be colored using elevation contours, which also improve depth persception on feature-poor surfaces.
• antialiasing - removes jagged edges at the expense of rendering speed
• smoothing - enables smooth shading
• transparency - higher quality rendering of transparent surfaces, which is useful for showing overlapping regions of meshes.
• camera position - get and set the camera position. This lets you find a good camera position using a low-resolution mesh and then make a screenshot from the exact same position using the high-resolution version of the mesh with bells and whistles (e.g., antialiasing) activated.

Interface

Viewer accepts the following commands from the keyboard (note: the commands only work if the cursor is set to the arrow cursor and is placed inside the viewing window).

• 1 - prints the current camera position and orientation
• 2 - saves current view as an rgb file (sgi only).

Files

Viewer.c command line interface

mtViewer.c the mtViewer class, which is derived from the Inventor ExaminerViewer class

Usage

Usage: Viewer - View an inventor file

Detailed Usage

%S                      wrl file [required]

Inventor file to view.

-view %f %f %f %f %f %f %f
                        set initial view (x y z q0 q1 q2 q3) 

Sets the initial view for the camera. The parameters for a partcular view can be determined using the keyboard command described above.

-save %S                save resulting wrlFile 

Saves the displayed scene as a wrl file. This can be used to record a mesh with grid or contour lines.

-noWhite                supress white background replacement

If this option is set, the background will revert to black, and the color of white objects will not be changed.

-smooth                 extra smooth shading 

Enables smooth shading

-antialias [%d]         use antialiasing with N passes [5] 

Inventor performs antialiasing by repeatedly rendering the scene with small offsets in camera direction, so using 5 passes take 5 times longer to display than with no antialiasing. Unfortunately, this also affects the speed of displaying while the scene is being moved, which makes it difficult to set up the camera position interactively when antialiasing is enabled (use the -view parameter instead).

-transparency           enable high quality transparency 

This is useful for visualizing overlapping surfaces

-grid [%f]              apply grid of size N to surface [1000.000000] 

A square grid with sides of the given size (in sensor units) is projected orthogonally onto the scene.

-contour [%F %F]        use color elevation contours with optional min and max range 

If this option is set, the mesh will be colored based on elevation. The hue of a vertex is set based on the projection of the vertex onto the axis formed by the up vector (see below). The hue is linearly interpolated along the up vector between the given min and max coordinate values.

-up %f %f %f            direction of up for elevation contours(up direction is 0.00 0.00 1.00] 

Sets the direction of the up axis for contour shading. By default this is +z, which is correct for most elevation maps.

Examples

Simple case, just view a mesh:

Viewer mesh1.wrl

Complex case, view a mesh with a grid (using default 1000 unit squares), color contour (elevations between 0 and 5000 will have color variation), and antialiasing (10 passes):

Viewer elev_map.wrl -grid -contour 0 5000 -antialias 10