This shows the current measured frame rate, averaged over the last second.

This shows the time taken to render the last frame.

This shows the rate at which triangles are being rendered and is a measure of how well your graphics card is working.

Culling is a process for determining items not to draw during the render of a scene. JetStream does a level of prioritized culling with the >drop-out method of rendering interactive scenes, but you have a certain level of control over other aspects of culling such as backface, near and far planes.

In order to maintain interactivity and guarantee a user-defined >frame rate, JetStream only renders what it can in the fraction of a second it has. The remainder is "dropped out", or not rendered. However, JetStream prioritizes what is rendered and what is dropped out based on size of the item's bounding box, distance from viewer and size on screen, so only the less significant items in the scene are dropped out. Once navigation has ceased, the scene continues rendering until all items are visible.

The frame rate is the number of frames per second (FPS) that are rendered in the main navigation window. JetStream guarantees a user-defined frame rate in order to maintain interactivity.

Codec stands for "COmpression-DECompression" and is a program that compresses and decompresses animations when creating and playing back .avi files. Codecs are installed independently of JetStream and are available when installed on your Windows system and the same codec that was used to create an .avi file is required to play it back.

When any native CAD file file is opened or appended, JetStream Roamer creates a cache file (.nwc) if the write cache option is set. When the file is next opened or appended, JetStream Roamer will read data from the corresponding cache file rather than re-converting the original data if the cache is newer than the original file. If the original file is altered, JetStream Roamer will re-create the cache file when it is next loaded. Cache files speed up access to commonly used files. They are particularly useful for models made up of many files of which only a few are changed between viewing sessions. Cache files can also be exported from some CAD applications where a native file reader is not available with JetStream Roamer. Cache options can be edited from the Global Options dialog box under the Tools menu.

Published .nwd files are useful when wanting to take a snapshot of the model at a certain time. All the geometry and review information is saved into the .nwd file and cannot then be changed. Published .nwd files can also contain information about the file, as well as being able to be password protected and time-bombed for security. These files are also very small, compressing the CAD data by up to 80% of the original size.

Published .nwd files are useful when issuing models for viewing by others with the NavisWorks Freedom free viewer, as well as being appendable themselves into Roamer to build up a larger scene.

Review files are useful when using the native CAD files appended into JetStream Roamer. They store the location of the appended files, along with any design reviews made in JetStream, such as comments, redlines, viewpoints, animations and so on.

If a group of files is appended into a JetStream scene, and saved as an .nwf file, then on re-opening this .nwf file later, once the original CAD files have been changed, the updated CAD files will be loaded into the scene for review.

External references (sometimes called reference files or "XRefs") are shown in Roamer selection tree as an inserted group. Roamer looks for the externally referenced files in the same place as AutoCAD or MicroStation would.

If the Unresolved XRef dialog box is shown, then this link has somehow been broken and the referenced files need to be relocated to where AutoCAD or MicroStation would expect them to be.

If these XRefs are not important for the current session, then you can Ignore the reference and the file will load without that XRef inserted. Similarly, Ignore All will load the file without any unresolved XRefs.

You can also use the DWG/DXF and DGN options in the Tools, Global Options dialog to set whether external references are loaded or not, giving you more control over file appending into JetStream.

During an export from a CAD package to .nwc, or while Roamer is reading a native CAD file, decisions must be made as how a curved surface is reduced to flat facets. For most applications and file formats, you have control over the level of faceting that takes place.

All items, no matter what their size, will use the same faceting factor and so have the same number of sides to curved entities. Therefore, you need to experiment a little with different values to account for the size that these items will appear on screen.

The faceting factor must be greater or equal to 0, where 0 results in the faceting factor being turned off. The default value is 1, if you double the value you get twice the number of facets, if you halve the value you get half as many facets. Larger faceting factors will result in more polygons to a model and larger JetStream files. There is little point having a large faceting factor if these curved entities are golf balls viewed from 200 yards!

For AutoCAD exports, the faceting factor is set from the NWCOPT command, MicroStation's faceting factor is set from Options , which is available from the NWCOUT export dialog, and the option to set the faceting factor on reading CAD files is found by choosing Tools, Global Options , and the relevant options tab.

Maximum facet deviation is used in conjunction with faceting factor to ensure that larger objects, with too large a deviation from the original, have additional facets added. If a difference greater than the entered value is found in a model it adds more facets. The values are measured in the model units.

Where d is greater than the maximum faceting deviation value, more facets are added to the object.

If the max faceting deviation is set to 0, then this function is ignored and just the faceting factor is used.

MicroStation shapes are polygons that can have 3 or more vertices. They're often used to model more complex objects which can waste memory. So, JetStream merges all shapes on the same level or in the same cell and with the same color into a "Shape Set" if these shapes have less than or equal to the number of vertices given by the Shape Merge Threshold

A composite object is a group of geometry that is considered a single object in the selection tree. For example, a window object might be made up of a frame and a pane. If a composite object, the window object would be both the frame and the pane and be selected all at once.

An instance is a single object, which is referred to several times within a model, for example a tree. This has the advantage of cutting down on file size by not unnecessarily repeating an object.

The original CAD or JetStream assigned identifier. Any item can have a name and this name will usually come from the original CAD package that the model was created in.

Every item in JetStream has a type. Examples of types are reference files, layers, instances (sometimes called inserts) and groups. Every CAD package also has a number of geometry types, for example, polygons, 3D Solids and so on.

The selection resolution is the level in the selection tree you start selecting at. You can cycle through items in the tree by holding down the shift key during a selection.

Each category and property name has two parts - a user visible string which is localized and an internal string which isn't and is mainly used by the API. By default when matching names in the Smart Tags and Find Items dialogs, both parts must be the same, but you can use the flags to match only on one part. You might use ignore user name if you wanted to match something irrespective of which localized version was being used.

The speed that the camera moves when turning right and left in any navigation mode.

Aspect ratio is the proportion of x-axis to y-axis size. For example, in exporting a bitmap of a viewpoint, maintaining the aspect ratio would keep the proportion of the view even if the number of pixels was different.

Anti-aliasing improves image quality by softening the jagged edge appearance of sharp lines. 2x to 64x refers to the extra number of frames that are required for the anti-aliasing process. The greater the number of frames, the finer the effect, (with the consequent increase in rendering time).

Navigation modes in which the camera is moved around the model (c.f. >model-centric

The field of view of a camera is the angle that the camera can see. A large field of view will fit more into the view, but will look distorted and a small field of view will tend to make the view more flat, tending towards an orthographic view. There are two fields of view in JetStream - vertical and horizontal. Editing one will change the other and the two are related by the viewpoint's >aspect ratio

The focal point is the position in 3D space that the camera will rotate around or zoom into in examine, orbit, turntable and zoom modes.

Navigation modes in which the model is moved in front of the camera (c.f. >camera-centric

The roll of the camera is its angle around the viewing axis. This cannot be edited in a navigation mode where the world up vector stays upright (walk, orbit and turntable).

Each viewpoint can optionally save the state of its hidden and "required" items, as well as any material (color and transparency) overrides. Then, on recalling the viewpoint, those same items are re-hidden, re-made required, and the materials reinstated. This can be useful in the creation of animations when dragging on viewpoints onto an empty animation.

This is indicated in the scene's units below (negative) or above (positive) horizontal (0) at the base of the tilt bar.

The direction that JetStream considers "up" is called the "world-up vector". This is maintained in the walk, orbit and turntable modes.