25.3. Object Editing Mode Techniques
This section will focus on techniques to use in Object Editing Mode. After reading this chapter, the user should have a good understanding on how to edit objects in Bulldozer.
25.3.1. Import and Export Objects
Bulldozer has the ability to load and modify 3D objects that were originally created in an external 3D modeling programs such as Rhinoceros. Bulldozer does not directly build 3D objects. Its purpose is to create scenes to be used by DIRSIG.
25.3.1.1. Import
Objects can be imported into Bulldozer using the Open and Open Object commands under File in the menu bar (see Section 25.2.2). When importing an object into the Bulldozer, the object must be in one of the following formats:
| Type: | File Extension: |
| Alias Wavefront | .obj |
| AutoCAD Exchange | .dxf |
| DIRSIG GDB | .gdb |
Usually when an object is imported into Bulldozer, Bulldozer displays a message stating it cannot find certain materials. This occurs because Bulldozer assumes every object file it loads is attributed with materials. It is safe to ignore this message for non DIRSIG GDB files.
Note: If the message appears upon loading a DIRSIG GDB file, it can mean one of two things. Either the object was never attributed, or the current material file loaded into Bulldozer doesn't contain the material ids contained in the object file. If the latter case is true, then try loading the material file used to attribute the object into the Material List.
After importing an object, Bulldozer by default displays the top of the object in the Viewing Pane. If another side is displayed, then the user should go back to their original 3D modeling program and correct the axis orientation for the object. This correction usually involves telling the 3D modeling program which axis is considered to be pointing "Up".
Note: The user should use the standard viewing angles in the View Selector to further check the orientation of the object along all its axis.
25.3.1.2. Export
When exporting an object to be used by DIRSIG, Save As under File in the menu bar should be used. This is to ensure that the object is saved as a DIRSIG GDB file with the ".gdb" extension. Save should only be used when the current object in Bulldozer was loaded into Bulldozer as a DIRSIG GDB object.
Note: The difference between Save and Save As is that Save will save the current object under the filename Bulldozer used to load the object, while Save As requires the user to specify a new filename and ensures the object is saved as a DIRSIG GDB object.
25.3.2. Object Transformations
This section will discuss some techniques on how to modify an object.
25.3.2.1. Orientation
Sometimes the standard viewing angles provided in the View Selector are not enough to view and edit an object with. As a result, Bulldozer provides a way to rotate and translate the view of an object manually. Changes made here are not saved in the final DIRSIG GDB object.
Note: While an object is being moved or rotated, it will be replaced by a wire frame box. This is so the program can respond faster to mouse movements. The object will be restored to its original representation after the change in orientation.
25.3.2.1.1. Rotating
To rotate an object, a mouse button has to be set to Rotate View in the Mouse Panel (see Section 25.2.3). Afterwords, click and hold the mouse button defined for Rotate View in the viewing pane and drag in the desired direction. Mouse movement should start off slow so orientation with the object will not be lost.
25.3.2.1.2. Translating
Translating allows the movement of an object along individual axis for an offset view of the object. To translate an object, a mouse button has to be set to Translate View in the Mouse Panel (see Section 25.2.3). Afterwords, click and hold the mouse button defined for Translate View in the Viewing Pane and drag the object to the desired position.
25.3.2.2. Object Editor
The Object Editor is a dialog box that contains options to modify the current object's anchor location and size. Object Editor is opened through Edit Object in the Part List (see Section 25.2.4). The editor contains two main sections:
25.3.2.2.1. Translate
Translate sets the object's anchor point along the X, Y and Z axis. Each axis has an option for Minimum, Mean and Maximum. Minimum sets the anchor point to the lowest point of the object, along the axis. Mean sets the anchor point to the middle point of the object along the axis. Maximum sets the anchor point to the top point of the object along the axis. For example, an object with the Z axis set to minimum will have the anchor point set at the bottom of the object.
Next to each option is an additional option for specifying an offset from the original anchor. This moves the object n units along the axis from the original anchor point.
25.3.3. Material Attributing
Material attributing is a process where actual spectral information is applied to every facet on an object. The spectral data includes links to specific thermodynamic and optical properties that will be used to model the surface of the object in DIRSIG Material. Bulldozer makes attributing a relatively simple and easy process.
There are two main ways to attribute an object, on the part level and on the facet level. On the part level, every facet within a selected part is attributed at once with the same material id. On the facet level, individual facets are attributed one by one.
To attribute an object, first set a mouse button to Select in the Mouse Panel (see Section 25.2.2). Next, choose an option under Select for facet level selection or part level selection. Click on a part or facet in the Viewing Pane to select it. Afterwords, select the material you wish to attribute with from the Material List, and drag it into the Viewing Pane. A dialog box will appear confirming the placement of the attribute. Click the OK button to confirm and the object will be updated with the new material.
Bulldozer also supplies a way to create, copy and edit materials to be applied to an object. The following describes how to modify materials:
25.3.3.1. Material Editor
See Section 11.4.3.2 for more information.
25.3.4. Correct Normals
When objects are exported from one application and imported into another application, facet normals sometimes are displayed incorrectly. To correct this problem, Bulldozer includes a way for the user to manually flip the normals on a single or group of facets.
To correct normals, a mouse button needs to be assigned Flip Normal in the Mouse Panel (see Section 25.2.3). Next, click in the Viewing Pane on the facet or part. When facets are flipped, each facet should appear darker or lighter in tint. To restore a facet or part, click on it again.
