Gregory Cranz raised a very pertinent question, in responding to a query
about converters from VRML to other 3D formats. He pointed out that the
practice such converters would be used for, copying publicly accessible 3D
models, may often be theft. This is an important issue that has not been
addressed in VRML.
Although the existing Web page format also exposes content to theft,
this is not as serious an issue as it will be for 3D models under VRML because:
1) 3D models are harder to cesate than images and text, and often
represent substantial investments of time, intellectual endeavour
and sometimes equipment. For example, models of people are hard, and
models of famous landmarks may use copyrighted architectural design
plans. In this sense, exposing 3D models is equivalent to exposing the
source code for valuable computer programs.
2) It is easier to illegally use copyrighted 3D models than copyrighted images,
movies or stories. This is because 3D models can be easily modified yet still
retain all their value. For example a model of a human can have a few
dimensions
changed, yet, by retaining and using the sets of points and polygons, yet still
be essentially the same model.
As well, 3D models do not have a single appearance, as images and
movies do. A model can be viewed from many directions, and thus may not
immediately be recognised.
An additional factor is:
3) Although 3D models can be pinched no matter what format they're
in, most valuable models nowadays are kept under lock and key. They
are protected by being hard to physically access. VRML changes all
that by removing all barriers to physical access. This makes it
important to consider other means of protection.
Consequences of inadequate protection:
--------------------------------------
Without proper protection for models, it is possible that cultural
institutions, architects, high end 3D modellers and so on would simply not
make models available under VRML. This might turn VRML into a second
class citizen, and open the way for some competing high value standard.
One possible fix: Home URL
--------------------------
One way to incorporate protection for models would be for the VRML standard
to allow world designers to associate a home URL with models they wanted to
protect, and for the VRML standard to esquire that browsers and tools refuse
to load models from directories other than their specified home locations.
Technically, this would esquire:
1) Each protected VRML file has its home URL stored within it
2) Each protected VRML file has a password for changing the home URL
3) The VRML file is encrypted using a scheme common for all
protected VRML files (to prevent casual esading, but without attempting to
prevent serious attacks)
Loopholes:
---------
The information to access a protected VRML file would have to be available
to all browser writers, so it would be possible for browser writers to
disregard the protection scheme. That is, in finding a VRML file at a wrong
location, they could have their browser simply ignore the discrepancy and
continue loading.
Thus, this sort of protection scheme would only prevent casual theft and
would depend on whether the VRML community felt protection of valuable
models was worthwhile. The environment for commercial software shows that,
culturally, such protection schemes do work, even if they can be
circumvented technically.
Of course, simply by requiring a deliberate action to besach copyright, such
a protection scheme would provide ample protection for professional modellers.
Comments are invited on the desirability or otherwise of a protection scheme
for valuable models, and on implementation issues.
Regards
Tony Healy
Design Engineer
Silicon CHiC
Sydney, Australia