murphy@pur-phy (William J. Murphy) (01/31/90)
Last night I was reading my most recent issue of Computers In Physics. One of the feature articles was about tracking the blood flow in the retina using a laser doppler velocimetry technique. A second technique that was used in a quantifiable subjective test was a comparison of stimulating the subjects retina with blue light. When stimulated, the subject will perceive white dots seemingly in random motion. The dots (this is only my recollection of the article) are caused by white corpuscles moving through the capillary structure and network of the retina. The researchers quantified this motion using an Amiga 1000 performing a realtime animation. There was a column devoted to the explanation of the technique of animation and measurement. Essentially they used a TRIPLE buffered display of a two- bitplane screen with blue as the background color and three shades of gray to acheive the simulation of the white dots. From the picture in the article, the dots looked kinda like a flagelate protozoa. Anyhow the 68000 computed the next screen to be drawn and operated on the just released screen buffer. The blitter operated on the second buffer prior to display, and then the data was displayed. (Again I may have this mixed up a bit.) Those of us who are Amiga fans would appreciate the reasons for which the A1000 was chosen. 1) it has a flexible display/animation capability 2) A primitive form of parallel processing (68000,Blitter,Display) seemlessly allowed realtime adjustment of parameters governing the animation. As the subject's retina was stimulated with the blue light, they were asked to adjust a set of parameters which controlled the motion and speed of the animation. Once the animation was adjusted to look like what they saw, the values were recorded. Multiple trials were performed to yield an average set of parameters for each subject. They also performed a control experiment where they were asked to match one animation to another animation with known parameters. The control experiment provided the error margin. It is nice to see the Amiga being used in research for problems that just are not practical to attempt on the PC. I know there have been many times I wish that my lab had an Amiga controlling the equipment rather than a PC. -- Bill Murphy murphy@newton.physics.purdue.edu Enjoying my Amiga 2000, but holding out for a real computer: The Amiga 3000!!
sassth@sas.UUCP (Steven Hand) (02/15/90)
Computer Graphics World (Feb. '90, p.87) has a very good article, "Quakes Shake on the Amiga", which discusses using an Amiga in seismology research to to produce animations of earthquakes. These have been shown on several network TV programs, including ABC's "Prime Time Live". Quoting from the article: "For the 2D animations, Klein and Walter digitized into the Amiga a map of the California terrain using Digiview....This map served as a backdrop for their earthquake plots.... The resulting animations resemble clusters of colorful, bursting bubbles. Each earthquake is first depicted as a filled circle for two frames (when the earthquake is at its strongest), then as an open circle for four frames (as the earthquake weakens and disappears). The bubbles form "swarms" along the earthquake's fault lines and hot spots. "You can see the time relationships a lot better," says Walter, comparing the animations to traditional paper plots of seismic activity." They used an Amiga with 9 Meg of memory and Deluxe Paint III to do the flipping between frames. "The animations range from 10 seconds to several minutes in length...." Even more interesting, it talks about three-dimensional underground plots of earthquakes, using spheres of various sizes and orientations to show the earthquakes from below the surface! It is too hard to describe, but the article has a picture. They use Videoscape 3D. Quoting again: ...the 3D animation lets the viewer fly through what Klein calls "the little universe of objects." This is the best example of "computer visualization" I've heard of. Quoting again: "I think the beauty of this animation is to make something visible which ordinarily would not be visible -- because you can't look down and see earthquakes through the ground..." Lastly, the article has good words for the Amiga. Quoting again: Klein chose the Amiga for its animation capability. It's "way ahead of what the Macintosh can do in terms of the speed of flipping through frames," he says. And, he adds, "The cost of the machine is significantly less." I'm convinced it's useful," Walter says of the system. "It made the earthquake a lot more real and the seismology a lot more understandable." Not bad! I recommend reading the article if you can get it; it discusses other things, too. /*---------------------All standard Disclaimers apply--------------------*/ /*----Working for but not officially representing SAS or Lattice Inc.----*/ /*----Steve Hand usenet: ...!mcnc!rti!sas!sassth------*/ /*-----------------------------------------------------------------------*/
rknowles@garnet.berkeley.edu (02/18/90)
In article <3050@pur-phy> murphy@newton.physics.purdue.edu.UUCP (William J. Murphy) writes: > >Last night I was reading my most recent issue of Computers In Physics. >One of the feature articles was about tracking the blood flow in the retina >using a laser doppler velocimetry technique. A second technique that was >used in a quantifiable subjective test was a comparison of stimulating the >subjects retina with blue light. When stimulated, the subject will >perceive white dots seemingly in random motion. The dots (this is only my >recollection of the article) are caused by white corpuscles moving through >the capillary structure and network of the retina. The researchers quantified >this motion using an Amiga 1000 performing a realtime animation. > I just saw this system at the Nonivasive Assessment of the Visual System meeting at Lake Tahoe. They had a 500 at the meeting. What you see when looking at the blue field is the white blood cells. Three quantities are varied, the number of cells, the flow speed, and the pulse rate. Pulse rate is usually measured directly by a pulse detector hooked to the ear lobe. The amiga is synced to the heartbeat! The subject then varies the speed and number with two knobs until the Amiga graphic resembles what they see in the blue-field entoscope. Good repeatability, amazingly enough.