Creating VRML Cave Images
This page contains detailed information about creating cave
images, using VRML, trouble shooting and problem solving.
I. What Happened To XWEB? If you have used
Compass in the past, you probably know that you could use XWeb to
display 3D cave images on the internet. Unfortunately, a couple years ago,
Microsoft found a security problem in XWeb and decided not to
support it any longer.
II. Why VRML? In many ways, VRML is a better option
that XWeb. First, it can be used on virtually any browser and
virtually any computer. There are VRML plug-ins available for PCs, Macintoshes,
Unix and Linux machines. It also simplier and easier to use.
III. Trouble Shooting.
Here is information about solving problems you may have displaying VRML images:
1. Plug-Ins. Before you can view VRML images,
you must have a VRML viewer installed in your browser. There are versions
available for virtually any computer, operating system or browser including
PCs, Macintoshes, and Linux based computers. Here are some links to browsers
for various computers:
2. Settings. Most plug-ins have settings that
allow you to control the VRML image appearance. Normally, you access these
setting by right clicking on the VRML image. By adjusting the settings, you
can often improve the quality of the image. For example, with the
Cortona plug-in, switching to the "R98 Renderer" can improve the quality of
transparency in an image.
3. Image Size.
The cave images can be fairly large. If you have a slow internet connection,
it can several minutes for the image to load. Like wise, be aware that if
post large images on the internet, it may be difficult for people with
slower connections or slower computer to view the cave.
4. XP Service Pack-2. The latest software
update for XP, Service Pack-2, automatically disables all ActiveX controls
in Internet Explorer. Since the VRML plug-in is an ActiveX control, Explorer
may give an error message if you try to display a VRML file. In my
experience, this will only happen if you try to view the image on your own
computer. Normally, no error appears if you are viewing the image on the
If the browser does give error when displaying a VRML
vision, you simply click on the error message bar and select the "Allow
Blocked Content" option. You can also completely disable ActiveX blocking,
but for safety reasons, Microsoft advices against it.
IV. Performance. When your
browser displays these cave images, it must process a lot of information. For
example, in order to draw the image of Fulford Cave, it must draw, shade, light
and shadow 5,000 polygon surfaces. For this reason, faster computers are
generally better. This is particular true of very large caves. With caves such
as Wind Cave or Lechuguilla were the passage lengths approach 100 miles (160km),
only the fastest computers will give satisfactory performance. For this reason,
you should choose your subjects carefully. You also have to consider that very
large caves on a web page may take several minutes to download with a dialup
V. Posting Your Own VRML Images.
It is very easy to post your own VRML images on the net. First, you
must generate your own VRML Cave image. You can do this using
several programs including CaveX and the standard Compass Cave
Viewer, which are available at the
main COMPASS web page. Once
you have created the VRML file, you just upload it to your web
page area and then insert the following block of code into your
Entering The Code. To use this code, enter it exactly as
written into the HTML for your web page, substituting the name
of your VRML file for "secret.wrl". The code must be entered
into the raw HTML form, which means that you cannot just drop it
into the web page editor display. You must use the "View HTML"
or "View Source" option in your web editor.
More Information. For more detailed information about
using VRML in web pages,
VI. Using Your Browser As A
Viewer: Once you have installed a VRML plug-in in your
browser, you can use it to view any VRML file, including files
that are not posted on the internet. You just click on the file
and your browser will display the image. Note, if you are using
Windows XP Service Pack-2, you may experience the error message
described in section III. 4. above.