Introduction

Geocap is a 3D visualization platform that uses an open-source visualization library from Kitware called visualization toolkit (VTK). Together with the specialized visualization techniques developed by Geocap this library provides you with endless opportunities when it comes to visualization.

This chapter will explain basic visualization concepts in Geocap and how to visualize the most common data types in Geocap. Thus it is important that you know how the graphical window works in Geocap. You should also be comfortable with the commands concept and how these are execute on datasets. Read more about these topics here:

In this section:

Actors

In display context an actor is a graphical term for a visualization unit. A complex display is created by a set of actors. In Geocap the basic principle is that a display command creates one or several actors.

Showing how actors are visualized in the project

An actor can have different properties like:

Visibility - Can be 1 or 0. Used to toggle an actor on and off. Applied by the project manager when toggling the check box.
Opacity - Can be between 0 and 1 and tells the transparency of the actor.
Pickability - Can be off (default) or on. Positioning the cursor and hit y on the keyboard sets all the actors to pickable so that the cursor marker can stick to the actor being found.
Ambient light - Will determine an actors brightness.
Reflected light - Determines how much light is reflected.
Diffusion - Determines the spreading of light.

To adjust these parameters right click the actor in the project manager and select Appearance, or you can click the icon in the main toolbar and then click on the actor you want to change the appearance of in the graphical window.

Decimation

The default procedure is to use decimation when displaying a large grid. The actual decimation is listed in the lower toolbar to the left. The user can turn decimation on/off if necessary. Decimation option is found on the Map command menu. Overall decimation is handled by the shell command:

spe dlev number

Specify display level in decimation (0 - 4). 0 is no decimation,1 is default.

2D, 3D, Isometric and Stereo

2D and 3D are graphics terms for how many dimensions are present in the visualization window. In 3D all mouse buttons are active and the graphics can roll, pan and zoom in all directions. In 2D mode the roll function is disabled and the viewpoint is positioned along the x, y or z axes. This is particularly practical when digitizing and getting an overview. The majority of editing is also completed in 2D.

You can switch between 2D and 3D with the icons on the toolbar. Sometimes when zoomed in on a detail in 2D a nice feature is to go directly to 3D isometric view in order to see the detail in 3D. This is done by toolbar View > Perspective > 3D Isometric.

There are also icons on the main toolbar for viewing along any axes.

Stereo view is achieved creating a new graphics stereo window: *toolbar > Windows > New > Stereo View > *. The prerequisite for seeing stereo is that there is a connecting device that delivers stereo signals.

Scaling

Scaling is normally performed in the Z-direction in order to see the structure of a surface or seismic section more clearly. Scaling in Z-direction is done by scrolling the mouse wheel or by using the actor scale menu. This can be reached from the icon on the main toolbar. This menu also provides scaling in X- and Y-direction which will stretch the data set.

Z-axis direction

Geocap has the option of letting the Z-direction point upwards or downwards with positive values by using the and icons on the main toolbar. The advantage is that when operating below the sea level all values can be positive. If one prefers to have positive values above sea level and negative below sea level the z axis should point upwards.

The default use in Geocap is to operate with positive values when doing seabed and reservoir modeling. If seabed modeling is combined with land modeling it is optional which direction the Z-axis should point. If sediments and seismic are present with positive Z-values, it is most convenient to let the z axis point downwards.

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