The first commercial product using the technology is the Automatic Culture Generator (ACG) built by CGSD and licensed to Terrex as a plug-in to their terrain generation software. We should point out that "culture" is simulator jargon for "objects which sit on a terrain surface in a database," such as buildings, trees, and the like. Announced in late 1998, the product entered test in April 1999, and was publicly demonstrated at the International Training Equipment Conference (ITEC) at The Hague in the Netherlands. (What is wrong with the house shown above? The steps to the porch are missing! That is being fixed.)
All the images linked to this page were generated by Terra Vista and displayed on an Intergraph computer using a viewer developed by CG2. The screen captures were then cropped and contrast adjusted in Adobe Photoshop.
The current release of the ACG generates multiple architectural styles of residences typical of the United States. The styles include California Ranch, Cape Cod, and several varieties of Folk Victorian. Also included are commercial and industrial building styles built either as point features or according to a specified outlined footprint. Many of the buildings are landscaped with lawns, trees, bushes, and fences. The buildings are generated in a great variety of sizes, shapes, and combinations of colors and material textures. There are quite literally tens of thousands of unique buildings for each style, and each is automatically generated with the multiple levels of details needed for use in serious real time simulation.
People who saw even the most preliminary versions of the product were impressed. Making a database model like a building by traditional hand modeling methods typically costs more than $1 per polygon. Consequently, users have found a way to be happy with a small collection of building models, perhaps a dozen or two, that are replicated throughout a large database. As far as we know, until the demonstration of the Automatic Culture Generator no one had ever seen a database with thousands of unique buildings in it. It is, perhaps, more impressive than it ought to be, but nonetheless truly remarkable.
The image below shows buildings generated from a supplied ground footprint.
Cape Code house includes model and low resolution textures in Winzip .
Yes, once the database is created it is indistinguishable from one that was made by hand. Any building can be copied, moved, deleted, or modified as desired.
Are the models taken from a library and then automatically stretched or otherwise slightly varied?
No, each model is generated individually according to rules that describe the style.
If the database is recreated to fix unrelated problems, will the ACG models be the same?
Yes, unless deliberately reseeded, the models will always be the same, regardless of the order in which they are generated. If the database is made in blocks, individual blocks can be created independently in any order and the models will always be the same.
Can users define new building styles?
No, not on their own. The style information is coded in the software. We can build custom styles for clients. Eventually, we would like to make styles definable by users, but that is a long ways off.
Is the parametric building software easy to write?
No, it is surprisingly difficult. We have been working on it for nearly five years, including one complete "throw it away and start over" attempt. Another obstacle is that the software requires hundreds and hundreds of photographically-derived texture patterns; we have spent years building a library of thousands of patterns.
How much detail is in the buildings?
Currently, low resolution models start at about six or eight polygons, and the high resolution versions go up to a few hundred polygons. We presently intend to make versions of the software which will produce buildings with up to a few thousand polygons in the highest resolution.
Don't the databases get rather large with all those polygons?
Yes indeed. Companies that make 20 G disks should be sending us money and cheering us on, but, alas, that hasn't happened so far. The algorithms could be used to generate the models on the fly, just before they are needed by the real time. Since the high resolution models are not needed unless the user gets close to a building, most of the polygons that are potentially available would then never be generated.
What can be done besides buildings?
We have done buildings and a certain amount of landscaping. Complex vegetation like forests are next. Also, transmission towers and water towers. Further along, we plan to do detailed roads and highways.
Can models be tailored to the general characteristics of the database?
Yes, this is done in several ways. One way is to have the database program provide more parameters to the building generator. For example, if the height, width, and depth are known, they can be supplied. Also, information about the type, style, and other attributes could be provided.
Is the technology only available through Terrex?
Our agreement with Terrex provides them with an exclusive license for use in generating buildings, towers, and forests in automatic terrain generation software for a period of one year. The technogy is available immediately for terrain viewing applications, for generating other types of objects, for interactive modeling applications, and for other applications. It will be available for general licensing after the one year period of exclusivity.
For More Information
Contact Roy Latham, firstname.lastname@example.org