SethSandler » Projector

NUI Group announces Multitouch Technologies book release!

SethSandler — Sat, 06 Jun 2009 19:16:45 +0000

The long awaited Multitouch Technologies book authored by members of NUI Group (http://www.nuigroup.com) has officially found it’s first release! As one of the co-authors of the book, I am proud to see a final initial version come to fruition. The book, which consolidates articles from the NUI Group Wiki, includes sections on how to build Multi-touch devices, multitouch software resources, a glossary of terms and more. I believe, as the book develops further, this will be the best resource for multitouch information on both the web and in print.

If you’re unfamiliar with NUI Group, I suggest reading the about page http://nuigroup.com/log/about/. NUI Group is currently the single best resource for multitouch technology and hopefully will become the largest database for Natural User Interfaces and emerging technology. If you’re interested in do-it-yourself hardware/software, HCI, or multitouch interaction, NUI Group is the place to be.

If you like the book, leave some feedback below! If you’d like to contribute to future sections of the book, you can get involved here: http://nuicode.com/projects/wiki-book

Download the Book | Submit Feedback | Join the Discussion

Projector Latency…

SethSandler — Tue, 18 Dec 2007 21:45:11 +0000

Latency is a time delay between the moment something is initiated, and the moment one of its effects begins or becomes detectable. When it comes to projectors, latency refers to the time difference between the computer screen and projection from the projector. There will always be some latency (time difference) between the source image (computer) and the displayed image (projector).

Laurence Muller has a Beamer Latency Measurement Tool v0.2 that will measure the latency of the projector. Ideally anything under 20ms is really good. For multitouch, if the latency of the projector is high, there will be visible lag between finger movement of objects and the projection of these objects.

Here are the screenshots of my projector (Casio XJ-S30) and notebook performing the Beamer Latency tool. It’s simple to use. You load up the program on your computer and set the refresh rate to 60hz, mirror the image on the projector, and take a picture with camera set on 1/60th. Since the display is running 60fps (fixed in opengl gamemode) a delay of one bar means 1/60 sec = 16.667ms.

Larger View

As you can see, my projector (Casio XJ-S30) has less than 1 bar latency which means I have less than 20ms latency which is great. I recommend this tool when testing projectors.

Projection Screen tests…

SethSandler — Fri, 23 Nov 2007 19:01:24 +0000

I took some pictures of the projector projecting on 3 different types of materials. I’m using a Casio XJ-S30 Projector which has 2000 lumens and 1800:1 contrast.

The following images consist of Rosco Grey Projection Screen (left), tracing paper (middle), and Rosco Black Projection Screen (right).

Here’s one picture with the lights on with Rosco Black (left), and Rosco Grey (right). In the picture the Rosco Black may look slightly better, but in person the Rosco Grey is the clear winner.

It’s really hard to get an accurate picture of what these projections look like in person. The camera seems to make white areas look washed out when really they are clear and bright. In person, the tracing paper has the best brightness and clarity. The Rosco Grey also has nice brightness and overall clarity, but the tracing paper is slightly better (in person). The Rosco Black seems to dull the colors too much. Maybe a brighter projector would bring out the best in the Rosco Black, but with my tests it’s just not an option for use.

The winner in viewing tests:

Tracing Paper
Rosco Grey
Rosco Black

Conclusion:

The tracing paper only has a slight advantage and since Rosco projection screens have the bonus of blocking outside infrared light, the Rosco Grey is the best option and therefore Rosco Grey will be what I’m using (for now at least).

Rosco Projection Screen

SethSandler — Tue, 20 Nov 2007 00:14:04 +0000

Rosco Projection screen is an inexpensive projection screen that seems to give pretty good results. There’s a few places online you can buy it. I ended up purchasing it from rosebrand.com. All places sell by the yard and the the minimum size is 55″ by 1 yard. The price is $15 per yard at 55″ width. I ended up buying both the Rosco Black and Rosco Grey to see which would work best with my setup.

Screen comes packaged on a roll.

Rosco Grey on the roll and Rosco Black on top

Unrolled: Rosco Black on bottom and Rosco Grey on top

The minimum size is quite large and is almost 3 times the amount I need. So really you’re getting a good deal with the cost of this material. It’ll last if you need to do any tests, or are making multiple or very large displays. It cuts easily with scissors as you can see from the picture above of the Rosco Grey cutout.

As far as the feel of the projection material, it is great! Very smooth and very low friction which means dragging objects on screen will be very easy. Friction is one of the most important factors when considering a surface. High friction means that it will be hard to move your finger. Rosco seems to be a great projection material with low friction.