三维建模之Organizing Your 3D Scene

Organizing Your 3D Scene

Well, a few weeks have gone by since our last newsletter went out. In the interim, hopefully all of you have received a box from ESRI containing ArcGIS version 9.0 and have loaded it on your system. If you do not have a license for 3D Analyst, know that when you license your software you will be given the opportunity to evaluate the extension for 30 days. We hope you will take the opportunity to explore the 3D world. We have spent part of the past several weeks reading some of the version 9 manuals for the first time and testing the software. Having not seen the “Understanding 3D Analyst” manual during the beta program, we found several things that have been very helpful. Much of what we now understand relates to the importing and handling of 3D Symbols in ArcScene and ArcGlobe, which is our topic for this newsletter.

It would be very easy to begin importing custom trees and structures into your ArcScene or ArcGlobe environment without regard to possible future organizational issues. ESRI provides a very nice way to manage all of your custom 3D Symbols using STYLES. Up to this point, most of us have probably made very little use of the Style Manager. It is accessible from the ArcMap, ArcScene and ArcGlobe environments. How many users actually understand Styles? We think this is key to your ultimate success in 3D scene creation, so we are going to devote much of this newsletter to the concept of Styles and their storage of our custom 3D symbols. ESRI’s discussion of styles and symbols can be found in chapter 8 of “Using ArcMap” in the on-line documentation. Information specific to 3D symbols can be found in chapter 9 of the “Using ArcGIS 3D Analyst” manual; this is also in the on-line documentation.

What is a Style and What is a 3D Symbol?

So what is a style? ESRI’s definition left us a bit confused. Were the 3D models of trees and buildings we made and then converted to 3D symbols for use in ArcGlobe or ArcScene styles or symbols? Answering that question is perhaps best done with an analogy. For example, each person you know is different from every other person. They are of different heights, weights, complexions, beliefs, and interests and have particular clothing preferences. In short, they have their own style. The same could be said for a USGS 1:24,000 scale topographic map. This 2D map conforms to a particular style, where the colors, symbols, scale bar, etc are standardized, giving it a particular look and feel. Now let’s consider a 3D scene. Most trees and buildings are unique to a particular area or community and when other common features like signs, light posts and landscape objects are added, the scene takes on its own style. Wouldn’t it make sense if we could put all of the 2D and 3D distinctive representations into a common location, making access, use and sharing an easy task? Indeed, that is what is offered to you when you make use of styles in ArcGIS 9. It might be helpful to think of a style as a file folder, in which all of the different types of symbols, colors and feature representations are stored. This is exactly the way the Style Manager presents the many styles that come with ArcGIS 9. Take a minute and open the Style Manager by selecting “Style” from the Tool pull down menu option in ArcMap, ArcScene or ArcGlobe.

The Style Manager can be accessed from ArcMap, ArcScene or ArcGlobe.

Unless you have previously added additional styles you will see two style folders if you opened the Style Manager from ArcMap and three style folders if you opened the Style Manager from either ArcScene or ArcGlobe. These will be the ESRI.style, your personal style folder that was created for you when ArcGIS 9 was loaded and, if you launched the Style Manager from ArcScene or ArcGlobe, the ArcScene Basic.style. Chances are your personal style will be empty unless you have already created some custom feature representations. You can tell if it is empty by looking at the subfolders. White subfolders are empty and serve as placeholders for when you do add custom symbols or defining content. The ESRI style folder contains sub-folders with default symbols, map elements and properties of the symbols. All of these folders will be yellow (because they are not empty). With the ESRI.style folder open, click on the Marker Symbol folder to expose its contents in the right side of the Style Manager window. Try right clicking on one of the individual marker symbols and you will see that you can rename, cut, copy and delete the selected marker symbol. (CAUTION: Changes made to the content or names take affect immediately).

The Style Manager offers an easy way to view and manage styles and their contents.

Where Are These Styles Located?

When ArcGIS is installed on your computer, the default location for your personal style is C:/Documents and Settings/username/Application Data/ESRI/ArcMap/username.style. The ESRI default style is by default installed in the /Program Files/ArcGIS/BIN/Styles directory. This is also the location for all the other styles that come with the ESRI software. Notice that the styles all have names that relate to their possible use (e.g. Forestry.styles or 3D Buildings.style).

Adding and Creating New Styles

On the right side of the Style Manager window you should see a Styles button. When this button is pressed, it will expose all of the different styles that are available to you. These are all the styles that are located in the directory locations we just defined. Those of you with 3D Analyst loaded will see that you also have 3D styles available for selection. Selecting one or more of the styles in the list will add the folder to the window on the left side of the Style Manager window. As you probably realize, all of the new symbols contained in the newly added style will now be available to you for use in the Symbol Selector window to render your scene.

Creating a new style is a very simple process. When you press the Styles button in the Style Manager window, the bottom option is “Create New…” Selecting that option will start the naming process and set up the receiving structure for your new symbols and feature representations. Please go ahead and create a new style. Name it something like test.style, indicating that it can be deleted at a later date. Put it somewhere other than your personal style or default ESRI style location. Notice that this new style has now been added to the folder list in the Style Manager window. Opening the new style folder will expose all of the sub-folders. The custom 3D symbols that we will be creating will be placed in the “Marker Symbol” folder. Click once on the empty Marker Symbol folder to open it. Now right click in the window to the right of the Style Folder window. Right now you probably do not have any custom symbols to place in this folder, but if you did, you would right click in the right side of the Style Manager window and select the Add option. This will start a series of steps that will allow you to import a custom model in OpenFlight, 3DS or VRML format. We will save that process for another time. Instead, we have a few homework items for you to try.

1. Copy and paste a few marker symbols from other styles into the test style we just created. (You could also cut and paste, but that would remove the symbol from its original location.)
2. Change the name of the marker symbol.
3. Change the category text to be something else
4. Delete a marker symbol from this new style

Question: Is a style actually a file folder (directory)? Navigate to the location where you placed the test style you just created. Is it a directory or is it just a file?

Last Exercise: Start Access and then try to load test.style. What do you see? Yes, a style is merely a database with many tables that can be edited in Access.

Already Getting Starting in 3D?

Some of you have probably started making a 3D scene in ArcScene or ArcGlobe. If you are looking for software to begin making custom 3D symbols, you have probably found the reference to SketchUp™ and ModelBuilder 3D™ in the “Using 3D Analyst” manual. If you have questions about these items or other modeling packages such as REALnat™ please do not hesitate to ask us at info@gis-help.com. We can help!