The Geowall FAQ

Organizational questions

1. What is the GeoWall Consortium?
2. How do I join?
3. Do I have to be in the Earth Sciences to belong to the GeoWall Consortium?
4. What do I do if I have problems?
5. Is there a mailing list?
6. Are there any GeoWalls in my organization or geographic area?
7. I don't like the GeoWall name. Can I change it?
   

Purchasing questions

1. How much does a GeoWall cost?
2. Where do I buy a GeoWall?
3. Is there a company that can deliver an entire GeoWall?
4. Where can I get a current parts list?
5. Are there vendors that understand the GeoWall and stereo projection?

Projection questions

1. Do I need a special screen?
2. Can I use an existing projection screen in a lecture hall or meeting room?
3. What kind of projectors do I need to build a GeoWall?
4. Which projectors have been tested for use with the GeoWall?
5. These projectors run hot! Should I worry about overheating?
6. What is the difference between linear and circular polarization?
7. How do I fix a polarizer to a projector?
8. I've found some plastic sheet polarizing material. Can I use it to polarize the projector?
9. Can I use my existing projectors as part of a GeoWall?
10. How hard is it to align two projectors?

Hardware questions

1. What operating systems are supported by GeoWall software?
2. Which graphics boards will work with a GeoWall?
3. Does it matter which computer I use with my GeoWall?
4. Can I use an old workstation to drive a GeoWall?
5. What about laptops?

Software questions

1. Is there a list of software developed for the GeoWall?
2. What about applications that support OpenGL stereo?
3. Is there source available for the GeoWall applications?

Organizational questions

What is the GeoWall Consortium?
The Geowall project combines researchers and educators from geological and computer sciences to develop hardware and software for low-cost stereo visualization.
A good understanding of spatial relationships is a fundamental requirement in the study of the Earth Sciences. Traditional teaching methods have strongly relied on the 2D representations through maps and profiles that are occasionally augmented by physical models. Although most Earth Scientists have been trained to understand the 3D structure from such representations, the extrapolation requires spatial thinking skills that are difficult to learn and often form a stumbling block for students at the introductory level.

How do I join?
Send a check and a blood sample to… But really, build a wall and then enter it into the database. All are welcome.

Do I have to be in the Earth Sciences to belong to the GeoWall Consortium?
Not at all. We welcome everyone.

What do I do if I have problems?
Check the mailing list archives first. If your question is not answered there then post to the mailing list. Remember, you have to be subscribed to the list to post to it.

Is there a mailing list?
There are three. GeoWall Technical, GeoWall Community and GeoWall Classroom. The Digital Library for Earth System Education hosts it along with the archives.

Are there any GeoWalls in my organization or geographic area?
Check out the current database of GeoWall Consortium members and GeoWall locations.

I don't like the GeoWall name. Can I change it?
Sure. It's been done many times. It is also called Agave, AstroWall and just The Wall.

Purchasing questions

How much does a GeoWall cost?
A GeoWall is $6-10,000 for all the components. Some vendors charge more for value added systems and installation.

Where do I buy a GeoWall?
There is now one source for all the parts and software needed to build a GeoWall. Information about complete GeoWall solutions can be found in the solutions section. If you choose not to purchase a complete GeoWall setup, you will probably have to order from 3-4 vendors to get all the parts.

Is there a company that can deliver an entire GeoWall?
Again, refer to the solutions section for information on complete GeoWall solutions.

Where can I get a current parts list?
Right here.

Are there vendors that understand the GeoWall and stereo projection?
Yes. Check the GeoWall vendors list. These vendors are familiar with the quirks of stereo projection systems and often give preferential pricing to GeoWall consortium members.

Projection questions

Do I need a special screen?
Yes, it has to preserve polarization. There are only a handful of screens that will. Two manufacturers are DaLite and Stewart.

Can I use an existing projection screen in a lecture hall or meeting room?
Probably not. It has to preserve polarization. Unless it is very old it probably won't.

What kind of projectors do I need to build a GeoWall?
We generally use DLP projectors (Digital Light Projector). They are very bright and can be polarized without loosing any of the color spectrum.

Which projectors have been tested for use with the GeoWall?
See the current hardware list.

These projectors run hot! Should I worry about overheating?
DLP projectors do run hot. The Infocus 530s and 350 can both be stacked on top of one another without overheating. We also tried the Proxima x350s and they overheat in less than 30 minutes because of insufficient cooling.

What is the difference between linear and circular polarization?

How do I fix a polarizer to a projector?
The Eros Data Center has developed a very simple holder to attach 72mm Hoya Linear Filters to an Infocus 530 projector. The plan is to make them available through Rob Gag at ProjectorPoint.com.

I've found some plastic sheet polarizing material. Can I use it to polarize the projector?
Yes but it won't last long. The Infocus 530s put out so much infrared light that they will melt the filters in less than an hour.

Can I use my existing projectors as part of a GeoWall?
Maybe. If you already have a DLP projector you need to check if it will overheat when next to another projector. It is best to have two identical projectors so that they have the same optics. Also, the bulbs on DLP projectors degrade over time so you want to have bulbs that have had similar use. At the end of their 2000-hour life, an Infocus 530 projector will only put out about 1200 lumens. This is down from 2000 lumens when they come out of the box.

How hard is it to align two projectors?
We were very concerned with this in the beginning of the GeoWall project. It turns out that it is not very hard to get the alignment pretty close. With a little fiddling you can get it very well aligned. Be more concerned about vertical than horizontal offset since that seems to cause the most eye fatigue. You will be surprised at how sloppy you can alignthe projectors while retaining a good stereo effect.

Hardware questions

What operating systems are supported by GeoWall software?
Currently, there are GeoWalls that are based on Windows, Mac OSX, and Linux.

Which graphics boards will work with a GeoWall?
See the current GeoWall Hardware List.

Does it matter which computer I use with my GeoWall?
Not really. Keep in mind that you are spending $6000 on a pair of projectors and there is no reason to skimp on the computer. We have also found that many of the high performance graphics cards, such as the Nvidia Quadros, will run VERY slow if the AGP bus isn't fast enough.

Can I use an old workstation to drive a GeoWall?
Yes, but if you are trying to use interlace stereo you need to buy a box to extract two video signals from the interlaced source. Cyviz developed one solution but it is pricey compared to the cost of the GeoWall.

What about laptops?
We have been told by Nvidia engineers that the GeForce chipset that is used in many laptops can produce two video sources. They also said that no vendor has taken advantage of this feature.

Software questions

Is there a list of software developed for the GeoWall?
Yes.

What about applications that support OpenGL stereo?
Applications that support OpenGL stereo can be viewed using Nvidia Quadro2 cards using a Quad Buffered Clone Mode. This technique is just being explored. For further information look at the GeoWall page at the eMedia Center at the University of Wisconsin.

Is there source available for the GeoWall applications?
All software that the GeoWall Consortium produces is open source. See the software page for more information.