EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Icarus on July 06, 2015, 10:05:44 am
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Does scopes have "Z" axis ?
Where is it ?
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NO! The screen is a 2 dimensional space, x, y z is usually only used for the 3rd axis in a 3D environment like 3D modelling. Unless there is some obscure fucntion in a scope that I don't know about.
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The only form of "Z" is brightness. Some scopes have that, some don't. The input would be on the rear panel.
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yes i suppose the brightness could be considered the brightness as the brighter it is the further it goes in 3D space. I think someone had a bit of a complex when they called it that ;)
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(http://i.imgur.com/p3WorS8h.jpg) (http://imgur.com/p3WorS8)
Photo of page in a manual for an old Dick Smith Electronics scope (Huang whatever it is Chung, Chang, something like that rebadge).
It's intensity.
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maybe there is some PC based 4 channel scopes that can be setup to graph in 3D ?
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yes if you have an actual Z input you could create a 3D image of sorts in which case the name is pretty much right I just never realized that someone would think to modulate the brightness.
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Yes,it is done to insert markers,or as a video input for a raster display,& a few other things.
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yes if you have an actual Z input you could create a 3D image of sorts in which case the name is pretty much right I just never realized that someone would think to modulate the brightness.
TV/radar.
Or only want to look at part of signal, so turn beam on/off.
Or a more sophisticated form of persistence than is supplied by the phosphor.
Or given two-dimensional information, you want to display population density.
There are two meanings of "3D". The real one that has been around for >150 years, and the computer weenie one which is really 2D or, to stretch a point, 2.5D.
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Older analogue scopes have Z axis to control beam intensity via external signal. "Newer" analogue scopes have only internal beam blanking signal (either on or off) for retrace. Digital scopes does not have such concept at all, it can be done via other means.
As others mentioned, ability to control beam intensity allows to show more information on the same screen.
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Thank you everyone. I guess I should only consider X-Y for any modern day scopes.
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There are two meanings of "3D". The real one that has been around for >150 years, and the computer weenie one which is really 2D or, to stretch a point, 2.5D.
you use pencil and paper for 2D if your going to use a computer you might as well make the most of it. the introduction of 3D has brought an increase in productivity, why should I redraw something the manufacturer already drew ? I get no end of 3D models from suppliers of their products and it means I only worry about my bits and not theirs and they are so much more accurate than guessing and getting it wrong.
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There are two meanings of "3D". The real one that has been around for >150 years, and the computer weenie one which is really 2D or, to stretch a point, 2.5D.
you use pencil and paper for 2D if your going to use a computer you might as well make the most of it. the introduction of 3D has brought an increase in productivity, why should I redraw something the manufacturer already drew ? I get no end of 3D models from suppliers of their products and it means I only worry about my bits and not theirs and they are so much more accurate than guessing and getting it wrong.
You have 3D models. How do you display them in 3D? In particular, how do you ensure each eye gets only the correct image?
The least unsatisfactory way I have come across for ordinary screens is illustrated here: http://apod.nasa.gov/apod/ap140315.html (http://apod.nasa.gov/apod/ap140315.html)
Note, I have been taking 3D photos for 30 years (with a 1940s vintage camera https://en.wikipedia.org/wiki/Stereo_Realist (https://en.wikipedia.org/wiki/Stereo_Realist) ), so I have some experience of the subject.
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actual 3D display won't come for a long time as it's complicated and costly. Artists have been using 2D display methods to represent 3D objects for hundreds of years, the same methods are used by a computer, the only difference is that in a computer because you have the 3D data input you can redraw the model in any view at will.
Working in 3D I can design with close fit tolerances that I can't in 2D so well and would take much longer. The other thing with 3D is that you don't have to redraw each view because it can be automatically generated from the computer. Back in the day, one guy had an idea (the engineer) and loads of others (draftsmen) had to put it on paper for them. Where I work I get told horror tales of the days of pencils and paper where they would spend two weeks doing a drawing and just as it's finished they get told a dimension changed. so they spend days changing the drawing. It can take me seconds to minutes to alter a 3D model and that automatically changes the views on the 2D drawings of it.
Oh and I think we have drifted somewhat off topic but meh the original one was concluded I think.
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Thank you everyone. I guess I should only consider X-Y for any modern day scopes.
Definitely don't buy one scope over another because it lists Z as a feature. If a modern digital scope had this functionality it would probably all be in software, with something like another normal channel input being used as the brightness/colour axis rather than the traditional rear BNC.
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actual 3D display won't come for a long time as it's complicated and costly.
Not true. For a very long time there have been cheap, simple, practical, effective 3D displays - some of which are on computer displays.
3D displays have been around for exactly as long as 3D photographs, oddly enough. Since 1838, that's over 150 years. I have some from the 19th century. They even gave them away with Weetabix in the 1960s!
In some forms 3D photography is extremely simple, and in most forms it is well within the reach of amateurs. Back in the 50s it was a mass-market product advertised movie stars, e.g. https://uk.pinterest.com/brotherbish/stereo-3d-stuff/ (https://uk.pinterest.com/brotherbish/stereo-3d-stuff/)
Any colour computer display can display an anaglyph picture, such as http://apod.nasa.gov/apod/ap140315.html (http://apod.nasa.gov/apod/ap140315.html) which I view using a viewer given away by The Sun newpaper in January 1992.
Working in 3D I can design with close fit tolerances that I can't in 2D so well and would take much longer. The other thing with 3D is that you don't have to redraw each view because it can be automatically generated from the computer. Back in the day, one guy had an idea (the engineer) and loads of others (draftsmen) had to put it on paper for them. Where I work I get told horror tales of the days of pencils and paper where they would spend two weeks doing a drawing and just as it's finished they get told a dimension changed. so they spend days changing the drawing. It can take me seconds to minutes to alter a 3D model and that automatically changes the views on the 2D drawings of it.
There is no choice, you always have to work in 3D. (Or maybe 4D, if you want to include time).
Often you will use 3D computer models to represent 3D objects, and see the interactions between models on a 2D screen. Sometimes people working professionally will have expensive displays that enable them to see their 3D models in 3D.
Display technologies include anaglyph, field-sequential, crossed polar, and lenticular - plus some one-off oddities.
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Ah yes they came out with 3D cinema too, so maybe its close for the home user.
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Its been around for the home user for years. Any 120hz monitor can be used with lcd shutter glasses, many even have the IR sync transmitter built in. Anaglyph rendering has been around for even longer, but it doesn't look as good. Some TVs have cinema-style polarization, but that is used largely because the glasses are dirt cheap and it seems to be the most headache inducing of the technologies, because some of the image gets through to the wrong eye, depending on head position and such.
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There are two meanings of "3D". The real one that has been around for >150 years, and the computer weenie one which is really 2D or, to stretch a point, 2.5D.
Perhaps this might be of your interest https://www.oculus.com/en-us/ (https://www.oculus.com/en-us/) ? (Or any competitor in field of head mounted displays, there are plenty and consumer versions are just behind the horizon.)
No problems whatsoever, trough if you want to have full 360° image capture, you have to use lightfields (kinda ressembles hologram in quantized, low resolution form). True trough, thanks to the data troughput needed you will have to wait for lightfield videos bit longer, and till that time comes, you'd have to stick to "just" a 360° spherical videos (and guess why Dave is capturing EEVblog even in this format for some time now? ;) ). Problem with plain spherical video is broken stereoscopy of view in just about any head position except from regular vertical, also you cannot lean in / shift and look around in the bound volume with preserved true visual representation of captured place.
Of course rendered enviroments are nonissue-ish (low-poly only on low to mid-end PC), except for that none CAD manufacturer hadn't implemented native HMD support yet! \r. There are workarounds for model and assembly previews, trough.
As for CRO's, you can make them fully valid 3D display too - only thing needed is a bit of signal preprocessing and shutter glasses, as seen in just about any 3D cinema, or Nvidia 3D technology. Limiting factors are draw speed in both axis and display/tube presistance time. If I had more spare time on my hands, I'd do a 3D asteroids, but eh - for now, it's just a pet idea. I'd love to see somebody else to do it, trough.
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Ah yes they came out with 3D cinema too, so maybe its close for the home user.
Given a choice between stereoscopic (which I love) and a full 60Hz frame rate, I'd go for 60Hz. Ideally 60Hz and 70mm frame size, as in George Lucas' ShowScan.
Stunningly good 3D systems have been around for decades (and used by amateurs), but simple geometry indicates there have to be tradeoffs whatever projection/display technology is used.
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I have a very old B&K 10MHz analog scope. It does have a Z-axis input. It's on the back.
It doesn't look like the modern digital scopes have a Z input.
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The FLUKE scopes PM3394B and similar models had a rear BNC input, called Z-MOD
This was the external modulation of the CRT trace intensity.
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There are two meanings of "3D". The real one that has been around for >150 years, and the computer weenie one which is really 2D or, to stretch a point, 2.5D.
Perhaps this might be of your interest https://www.oculus.com/en-us/ (https://www.oculus.com/en-us/) ? (Or any competitor in field of head mounted displays, there are plenty and consumer versions are just behind the horizon.)
In early 2013 I tried an early Oculus when they kindly brought it to show my local HackSpace and University. I spent 5/10 minutes playing a VR video game. The resolution was low, but that's not a fundamental and I believe they have already improved it. I was interested in whether it might eventually work with the Condor gliding simulator, where you spend a lot time going in circles and/or spinning towards the ground e.g. real life
https://www.youtube.com/watch?v=8fZxuTKmmAU (https://www.youtube.com/watch?v=8fZxuTKmmAU)
or simulation
http://www.condorsoaring.com/media/movies/Discus2%20spin%20cockpit.zip (http://www.condorsoaring.com/media/movies/Discus2%20spin%20cockpit.zip)
I was surprisingly impressed, with reservations....
When the Oculus headset is on, nothing other than the game scene can be seen - unlike google glasses where the image is translucent and you can see round the edge of the glasses. I was surprised that the headpiece had no adjustments, but nonetheless the optics gave a good field of view and respectable stereo effect.
The demo scene was inside a room with internal upstairs balcony and external garden with tree overlooking a lake. The resolution was just about adequate for the demo but would, IMHO, be insufficient for seeing sufficient ground/cloud detail. Given the choice between stereoscopic vision and increased resolution, I'd opt for the latter. However, it was a prototype unit, and I see no reason the resolution could not be significantly increased.
Rotating my head about all three axes allowed caused the scene to change in exactly the way I would expect. This effect was good and compelling.
The stereoscopic effect was not overdone; it looked natural so that you didn't really notice them. That's the same as in James Cameron's "Avatar", and unlike the "poke something through the screen" that you see in most stereo films.
The "avatar" could be translated through the scene using a standard "top hat" games joystick. Moving forwards rapidly towards a wall caused me to involuntarily jerk my head back to avoid hitting the wall - compelling.
Using the joystick to turn the avatar slowly clockwise or anticlockwise worked as expected. However, doing that rapidly caused me to feel instantaneously nauseous, to involuntarily rotate my head up/down and move my shoulders. Most disconcerting.
So, if my head (and therefore my labyrinths) rotated and the scene moved correspondingly, all was well. If the scene rotated and my head didn't then I had problems. I conjecture this would probably be problem when practicing spins, and possibly when thermalling.
So, overall I really liked the panning effect, but disliked the resolution and disliked the scene rotating unless caused by my head's movement.
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I loved the PM3394B - amazing scope. If you get chance the to get one GET IT.
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I loved the PM3394B - amazing scope. If you get chance the to get one GET IT.
I know exactly what you are saying.
Over the years I have bought every single one that had a good price and was in good condition.
Right now I probably have at least 10 of them.
The specialty was with "all options" and I was lucky enough to get 6 of them in a bundle from a
government sale in the US a few years ago.
These days, people have less and less appreciation of this amazing scope.
I usually use 6 of them at once on my high voltage bench.
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There were many clever and useful applications for the "z-axis" on oscilloscopes. If you can bend your mind to ignore the association of z with the third axis in a Cartesian coordinate system you can probably figure many of them out, and perhaps invent something new. It is another way of presenting information.
An example that might trigger more interest in today's generation: Use one of the interrupts in your system (latched and cleared with the interrupt clear or return as appropriate in the system you are using) to drive the z axis. Then the display will only show during that interrupt and you can see the signals bouncing uncorrupted by whatever they are doing in other interrupts or in the main/background routine of the system. As long as the interrupts occur repeatedly at intervals shorter than the phosphor decay time (usually a few milliseconds) you will get a nice view of what is going on.
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The best use I found for the Z-intensity input of a scope was to play Spacewar!
As described in the "Ports to other systems" section of this article: https://en.wikipedia.org/wiki/Spacewar_%28video_game%29#Ports_to_other_systems (https://en.wikipedia.org/wiki/Spacewar_%28video_game%29#Ports_to_other_systems), I used two 8 bit DACs connected to my 8080 system, feeding the scope in X-Y mode, plus another output bit connected to the Z axis to turn the beam on and off.
In my high school electronics lab there was a teaching scope with a big TV CRT for the screen. I was really nice to use that to play it on. :)
This was back in the late 1970's.
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Fun Fact: the fact that analog scopes have an X, Y and Z (intensity) inputs is why the iconic Tektronix application note "XYZs of Using an Oscilloscope" is named that way.
Here are two videos I did that utilized the Z input:
https://www.youtube.com/watch?v=QCFBBiIm1h0 (https://www.youtube.com/watch?v=QCFBBiIm1h0)
https://www.youtube.com/watch?v=yf4kOMSPbM0 (https://www.youtube.com/watch?v=yf4kOMSPbM0)
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3D displays on an analogue X-Y scope:
http://www.glensstuff.com/3dpu/3dpu.htm (http://www.glensstuff.com/3dpu/3dpu.htm)
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3D displays on an analogue X-Y scope:
http://www.glensstuff.com/3dpu/3dpu.htm (http://www.glensstuff.com/3dpu/3dpu.htm)
2D display of a (nominally) 3D object.
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3D displays on an analogue X-Y scope:
http://www.glensstuff.com/3dpu/3dpu.htm (http://www.glensstuff.com/3dpu/3dpu.htm)
2D display of a (nominally) 3D object.
Is this kind of pedantry supposed to make you look smart? Read the introductory paragraph.
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I loved the PM3394B - amazing scope. If you get chance the to get one GET IT.
I know exactly what you are saying.
Over the years I have bought every single one that had a good price and was in good condition.
Right now I probably have at least 10 of them.
The specialty was with "all options" and I was lucky enough to get 6 of them in a bundle from a
government sale in the US a few years ago.
These days, people have less and less appreciation of this amazing scope.
I usually use 6 of them at once on my high voltage bench.
Now I'm not an envious person - but today I'm making an exception!!!
I had one back in 1995 (bought new for £5500+VAT) - I miss that scope so much.
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There are two meanings of "3D". The real one that has been around for >150 years, and the computer weenie one which is really 2D or, to stretch a point, 2.5D.
Perhaps this might be of your interest https://www.oculus.com/en-us/ (https://www.oculus.com/en-us/) ? (Or any competitor in field of head mounted displays, there are plenty and consumer versions are just behind the horizon.)
In early 2013 I tried an early Oculus when they kindly brought it to show my local HackSpace and University. I spent 5/10 minutes playing a VR video game. The resolution was low, but that's not a fundamental and I believe they have already improved it. I was interested in whether it might eventually work with the Condor gliding simulator, where you spend a lot time going in circles and/or spinning towards the ground e.g. real life
https://www.youtube.com/watch?v=8fZxuTKmmAU (https://www.youtube.com/watch?v=8fZxuTKmmAU)
or simulation
http://www.condorsoaring.com/media/movies/Discus2%20spin%20cockpit.zip (http://www.condorsoaring.com/media/movies/Discus2%20spin%20cockpit.zip)
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Nice gliding video,but they spoilt it with the dumb background music.
(I didn't look at the simulation-------sorry!)
Half of the experience of gliding is the near silence,with only the slight sound of air rushing over the aircraft.
In straight & level flight,there is very little sensation of forward motion.
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The simulation has captured the sound pretty well---not quite,but almost.
I needed to wind the volume right down,& as I said,it was close.
I joined a Gliding club back in the day,but it didn't fit well with shift work,& then,when I met my wife,that was goodbye to Gliding!
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3D displays on an analogue X-Y scope:
http://www.glensstuff.com/3dpu/3dpu.htm (http://www.glensstuff.com/3dpu/3dpu.htm)
2D display of a (nominally) 3D object.
Is this kind of pedantry supposed to make you look smart? Read the introductory paragraph.
Clear and accurate, not smart. Read the thread drift.
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Half of the experience of gliding is the near silence,with only the slight sound of air rushing over the aircraft.
In straight & level flight,there is very little sensation of forward motion.
Noise depends on how fast you are going; it is a good way of assessing large changes in airspeed without looking at the ASI. Too quiet => wake up fast!
What's straight and level flight? :) I'm always hunting for lift, chasing after buzzards, or just having exuberant fun. It is claimed that glider pilots that transition to powered flying have two problems: realising they can fly straight and level , and then managing to stay awake while doing do.
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I joined a Gliding club back in the day,but it didn't fit well with shift work,& then,when I met my wife,that was goodbye to Gliding!
Maybe you'll reconsider when you have a child (wonderful for their self-confidence, maturity, CV, being with them for longer), or decide that a little absence from a wife can make the heart grow fonder :) Have fun, safely.
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3D displays on an analogue X-Y scope:
http://www.glensstuff.com/3dpu/3dpu.htm (http://www.glensstuff.com/3dpu/3dpu.htm)
2D display of a (nominally) 3D object.
Is this kind of pedantry supposed to make you look smart? Read the introductory paragraph.
Clear and accurate, not smart.
Correct on the last point.
Read the thread drift.
I did.
Note, I have been taking 3D photos for 30 years (with a 1940s vintage camera https://en.wikipedia.org/wiki/Stereo_Realist (https://en.wikipedia.org/wiki/Stereo_Realist) ), so I have some experience of the subject.
Surely you meant stereoscopic photographs.
::)
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I loved the PM3394B - amazing scope. If you get chance the to get one GET IT.
I know exactly what you are saying.
Over the years I have bought every single one that had a good price and was in good condition.
Right now I probably have at least 10 of them.
The specialty was with "all options" and I was lucky enough to get 6 of them in a bundle from a
government sale in the US a few years ago.
These days, people have less and less appreciation of this amazing scope.
I usually use 6 of them at once on my high voltage bench.
Nice collection, what is "that" special on these scopes ?
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Surely you meant stereoscopic photographs.
Evenly divided. Some clubs are 3D, some stereoscopic, some stereo-3D. Here's a list of "3D clubs worldwide" http://www.stereoscopy.com/clubs/ (http://www.stereoscopy.com/clubs/)
3D photographs and projection systems have been around for >100 years. The only way of seeing 3D is to have two images, one for each eye.
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Half of the experience of gliding is the near silence,with only the slight sound of air rushing over the aircraft.
In straight & level flight,there is very little sensation of forward motion.
Noise depends on how fast you are going; it is a good way of assessing large changes in airspeed without looking at the ASI. Too quiet => wake up fast!
What's straight and level flight? :) I'm always hunting for lift, chasing after buzzards, or just having exuberant fun. It is claimed that glider pilots that transition to powered flying have two problems: realising they can fly straight and level , and then managing to stay awake while doing do.
The old Blanik I learnt in seemed quite capable of flying very slow & straight & level,& was very quiet.
I wasn't up to chasing buzzards,even if we had any around here. ;D
I had one adventure while learning,when the tow parted at 400ft(my fault).
The instructor got us down with a minimum of fuss,but those big jarrah trees at the end of the paddock were looking bigger all the time! ;D
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Half of the experience of gliding is the near silence,with only the slight sound of air rushing over the aircraft.
In straight & level flight,there is very little sensation of forward motion.
Noise depends on how fast you are going; it is a good way of assessing large changes in airspeed without looking at the ASI. Too quiet => wake up fast!
What's straight and level flight? :) I'm always hunting for lift, chasing after buzzards, or just having exuberant fun. It is claimed that glider pilots that transition to powered flying have two problems: realising they can fly straight and level , and then managing to stay awake while doing do.
The old Blanik I learnt in seemed quite capable of flying very slow & straight & level,& was very quiet.
I wasn't up to chasing buzzards,even if we had any around here. ;D
I had one adventure while learning,when the tow parted at 400ft(my fault).
The instructor got us down with a minimum of fuss,but those big jarrah trees at the end of the paddock were looking bigger all the time! ;D
Modern gliders are much quieter - unsurprising since noise=drag. Even so, they are noticably noisier at 100kt - and probably much much noisier at 200kt ;}
Round here sometimes the buzzards come and join you in a thermal, which is a delightful complement to your flying skills.
I've done very few aerotows, but had many winch cable breaks - great fun, except for the walk back! And deliberately entering spins at ~1000ft is fun too.
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Surely you meant stereoscopic photographs.
Evenly divided. Some clubs are 3D, some stereoscopic, some stereo-3D. Here's a list of "3D clubs worldwide" http://www.stereoscopy.com/clubs/ (http://www.stereoscopy.com/clubs/)
3D photographs and projection systems have been around for >100 years. The only way of seeing 3D is to have two images, one for each eye.
LOL. The Stereo Realist camera took 2D stereoscopic photographs (which merely give a very limited illusion of depth when viewed with the correct apparatus) , not 3D photographs in the true sense of the term. In that regard "3D" is a misnomer and a pendant like you shouldn't be using it. Or perhaps you managed to modify your Stereo Realist for holography.
As for my use of the words "3D display" in reference to my linked-to electronics project, I was clearly using the term in the same context as the title of the reference text that I cite: http://www.glensstuff.com/3dpu/ref.jpg (http://www.glensstuff.com/3dpu/ref.jpg) . I posted it because I figured that it was relevant to the OP's question about the possible utility of a Z-axis input for an oscilloscope display; not a response to any of your posts.
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Surely you meant stereoscopic photographs.
Evenly divided. Some clubs are 3D, some stereoscopic, some stereo-3D. Here's a list of "3D clubs worldwide" http://www.stereoscopy.com/clubs/ (http://www.stereoscopy.com/clubs/)
3D photographs and projection systems have been around for >100 years. The only way of seeing 3D is to have two images, one for each eye.
LOL. The Stereo Realist camera took 2D stereoscopic photographs (which merely give a very limited illusion of depth when viewed with the correct apparatus) , not 3D photographs in the true sense of the term. In that regard "3D" is a misnomer and a pendant like you shouldn't be using it. Or perhaps you managed to modify your Stereo Realist for holography.
Everything is "limited" in some way or another, so that isn't a distinction that throws any light (ho ho) on the subject.
As you correctly imply, holography != stereoscopic/3D - but that rather invalidates your point. Yes, I realise that many people are now starting to grossly misuse the term "holographic" - but that's irrelevant to this discussion.
I'll take holography seriously when it can show me an image of a candle or a chandelier or the sunset.
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Everything is "limited" in some way or another, so that isn't a distinction that throws any light (ho ho) on the subject.
As you correctly imply, holography != stereoscopic/3D - but that rather invalidates your point. Yes, I realise that many people are now starting to grossly misuse the term "holographic" - but that's irrelevant to this discussion.
That doesn't make sense
I'll take holography seriously when it can show me an image of a candle or a chandelier or the sunset.
Then I'll take stereoscopy and any pretensions of 3-dimensionality seriously when additional information about the subject can be reliably attained simply by altering the viewing position.
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Oh well, while we're all talking 3D and 2.5D...
If you're rendering 3D on a 2D surface - eg screen or printer.
Once you've identified your viewport surface and vanishing point coordinates...
You can scale your depth information back toward that vanishing point, (or project it forward toward the viewer) by decreasing (or increasing) the XY offset from the imagined line drawn between the viewpoint and the vanishing point...
A scaling value of approximately 0.6 gives a focal length that is close to that of the human eye's perception of perspective. Changing the value changes the 'focal length' of the 'image' presented to the viewer.
Have fun... this is the basic principle of 3D wire frames- and obviously with depth shading and light sources added you can do a lot more!
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For a 2 input oscilloscope I would expect X-Y mode to be available, for 3 input - X-Y-Z with a 3D diagram shown and for 4 input scope it could be a 4D diagram with 4th dimension translated to colour etc. My assumptions based on the fact that graphs like these are available in any math package like MATLAB or Mathematica, R etc. For high speed oscilloscope it is probably too expensive to provide that kind of functionality and usefulness is limited. 3D is a default plot for Real Time Spectrum Analysers.
In my Agilent DSO even X-Y sucks comparable to Tecktronix for example - that blurry, pink graph that they generate - I hate it. So if I want something pretty I record the trace to and then import it in MATLAB/OCTAVE - that is what this guy have done in this video:
https://www.youtube.com/watch?v=GuCdsyCWmt8 (https://www.youtube.com/watch?v=GuCdsyCWmt8)
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I'll take holography seriously when it can show me an image of a candle or a chandelier or the sunset.
You won't see true holographic recording of something, that is lightsource by itself, noncoherent by its nature. (Holographic recording with single noncoherent lightsource is possible, but only in limited and well defined optical path (read: microscopes, etc.)).
But as I already mentioned, there is a way around this (good 'nuff for digital era):
http://www.bmva.org/bmvc/2014/files/paper040.pdf (http://www.bmva.org/bmvc/2014/files/paper040.pdf)
http://home.otoy.com/otoy-demonstrates-first-ever-light-field-capture-for-vr/ (http://home.otoy.com/otoy-demonstrates-first-ever-light-field-capture-for-vr/)
You won't see lightfield videos for few years unfortunately, as it is obscenely data intensive - perhaps somebody comes with brand new compression method, as there is plenty of redudancy in image data.
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That's not really how it works.
To map real 3D objects (like a 3D model) into a flat, perspective image (2D) projective geometry is used.
Specifically: you (almost always) use a euclidean 3D space embedded in a projective 4D space (w=1, these 4D vectors are normalized homogeneous coordinates now). Then you can easily calculate a transform (as a 4x4 matrix) to map vectors in said space to a 4D space, manipulating image plane, fov, ... and so on. In conjunction with a w=1 normalization (perspective divide) you'll get your 08/15 flat 3D space. This 3D space is usually a unit space (hardware clips everything outside (-1,-1,-1)-(1,1,1)).
As your vectors probably represent fragments since a few steps you would do a simple Z (depth) comparison to decide whether to update a pixel in the frame buffer with a new fragment or not.
That's the gist of it.
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That's not really how it works.
You're right of course... I was trying to present a simple method for embedded bit-mapped solutions that presents the 'almost as good as' 3D visualisation, and specifically used in those days before we had powerful co-processors and GPUs.
Thanks for bringing that to the table! Cheers.. (BTW the mention of clipping was important. thanks!)
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My memory might be hazy but I think someone might have actually already posted a direct link to a ref. explicitly detailing the matrix transformation method. :popcorn:
https://www.youtube.com/watch?v=qp-4HP-WA1I (https://www.youtube.com/watch?v=qp-4HP-WA1I)
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Can't remember the last time I saw a CRO without a Z input. Reasonably rare to use it, but occasionally very useful. Using it to display a video image is something that everyone should try.
+1 for the Philips/Fluke CombiScopes. I have one here, though only a 2-channel model, and use it often. Would definitely pick up a 4 channel 200MHz version if the price was right. But then Philips were making great 'scopes long before the Fluke association.
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+1 for the Philips/Fluke CombiScopes. I have one here, though only a 2-channel model, and use it often. Would definitely pick up a 4 channel 200MHz version if the price was right. But then Philips were making great 'scopes long before the Fluke association.
The PM3390B was the top of the line 2 Channel version of this great Philips/Fluke combiscope and has almost all features at the 4 Channel version. Interestingly, they have dropped significantly in price in the US market but stay relatively stable in Germany or EU. For me, this was the ultimate scope in the 90's.
The design of these scope was done in Hamburg / Germany and they got all built in Almelo / Netherlands. I visited both places in the late 90's and was deeply impressed.
Most impressive was a Philips TV production line and hundreds of these scope installed for the TV adjustments in production. It was said in those days, that the development of these combiscopes was driven by the Philips internal demand for high end scopes. I still have the pictures of these factory visits somewhere, need to digg them out.
I probably have 5 of these 2 Channel scope as well on the shelf, all in pristine working condition.
The Z-Input was an option on all of these scopes.
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Yes, I'd love to see those photos :-+. Philips were doing great things back then, especially in T&M. Sitting atop my PM3380A is a PM6680 counter which is an extremely capable bit of gear. I've got about a dozen items of Philips test gear, and it's all very good indeed. Not everyone appreciates the quality of their stuff - there is a fair bit of brand snobbery out there.
Sadly my combiscope is one of the earlier ones - but even so, I'm very pleased with it. I didn't realise that Z-mod was an option - it's the only BNC on the rear of mine, and I admit that I assumed that it was a standard provision. What I really lament is the lack of Y-out - that's a facility that my main 'scope has, and I really like it. I sometimes connect that to a frequency counter, but usually it goes to an audio amp - for doing work with audio gear, it's incredibly useful.
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+1 for the pix High Voltage of the Philips factory.
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OK, I will look for the pictures. They moved with me to the USA and many years back to Germany.
Anyhow, I just had a new arrival last week, a 2 channel PM3370B in broken condition. (Did not turn on and had a high pitch sound)
Fixed the power supply today and now its working perfectly again.
I am just going through the detailed calibration procedure, including screen calibration.
Too bad these 2 Channel models do not have the 50 Ohm termination.
But they still show the signal from the Agilent 33520B perfectly
The generator is set to a 16 ns pulse (Channel 1) and 30 ns pulse (Channel 2)
Kind of impressive for such an old scope and only 60 MHz bandwidth.
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Ok, here is another test, this time with the Z-MOD BNC input used.
The scopes displays a 1 KHz sine wave in analog mode on the screen.
The Z-MOD is connected to the Agilent signal generator and is getting a square wave injected.
Changing the amplitude of the square wave does not influence the displayed sine wave.
Here is where it gets interesting:
Between a duty cycle of 1% to 50%, the brightness of the full sine wave is changed.
Between a duty cycle of 51% to 99%, the signal is partially clipped, essentially taking the signal partially away.
See pictures attached.
Picture 1 = 50% duty cycle
Picture 2 = 60% duty cycle
Picture 3 = 70% duty cycle
Picture 4 = 80% duty cycle
Picture 5 = 90% duty cycle