TIP: Creating a New CUDA Project with Visual Studio 2019

If you’ve installed Visual Studio 2019 and are trying to work with CUDA there are a couple of problems that you’ll encounter. The first is going to be an error that you receiving when trying to opan any CUDA project about missing properties. This is from the CUDA installer placing some of the files in the wrong place. It places the files based on what was in Visual Studio 2019 Preview. It was only recently that the full release of 2019 was made available (and for the full release theses files need to go into a different place). To work around that see this post for where to move the missing files to.

Once that is resolved the next problem is that the CUDA project templates are missing. An NVidia representative in the NVidia developer forums acknowledged the problem and says a fix will come in an upcoming release. Until then the current solution is to grab an existing CUDA project and rename it. If you need an existing CUDA project you can find them in the folder for the NVidia CUDA samples or download one from here:

https://devtalk.nvidia.com/cmd/default/download-comment-attachment/78613/

 

 

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Tip: Installing CUDA SDK on Visual Studio 2019

If you try to install the nVidia CUDA SDK and plan to use Visual Studio 2019 there’s an additional manual step that you’ll need to take. The installer available for the current version of CUDA (10.1) doesn’t specifically target the recently released Visual Studio 2019, but it will mostly work with it. I say “mostly” because after installing it you’ll find that the CUDA related project templates are missing and you can’t open the sample projects.

Fixing this is as simple as copying a few files.  Copying everything from the following folder

C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v10.1\extras\visual_studio_integration\MSBuildExtensions

Place it into this folder

C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Microsoft\VC\v160\BuildCustomizations

You may have to reply to administrative prompts. But once those files are copied you should have access to the project templates and the samples.

BrightSign HTML: Where is the Persistent Storage?

BrightSign Media Players work with a number of content management systems.  With a content management system, you can upload a BrightSign presentation as an asset and it will be distributed to the the units out in the field automatically.

Recently, I was investigating what the options are for other persistent storage.  The assets to be managed were not a full presentation, but were a few files that were going to be consumed by a presentation. As expected, the solution needed to be tolerant to a connection being dropped at any moment.  If an updated asset were to be partially downloaded, the expected behavior would be that the BrightSign continues with the last set of good assets that it had until a complete new set could be completely downloaded.

The first thing that I looked into was whether the BrightSign units supported service workers.  If they did, this would be a good area to place an implementation that would check for new content and initiate a download.  I also wanted to know what storage options were supported.  I considered indexedDB, localStorage, and caches.  The most direct way of checking for support was to make an HTML project that would check if the relevant objects were available on the window object.  I placed a few fields on an HTML page and wrote a few lines of JavaScript code to place the results in the HTML page.

Here’s the code and the results.

function main() {
    $('#supportsServiceWorker').text((navigator.serviceWorker)?'supported':'not supported');
    $('#supportsIndexDB').text((window.indexedDB)?'supported':'not supported');
    $('#supportsLocalStorage').text((window.localStorage)?'supported':'not supported');
    $('#supportsCache').text((window.caches)?'supported':'not supported');
    supportsCache
}
$(document).ready(main);
Feature Support
serviceWorker supported
indexedDB supported
localStorage supported
cache supported

Things looked good, at first.  Then, I checked the network request.  While inspection of the objects suggests that the service worker functionality is supported, the call to register a service worker script did not result in the script downloading and executing.  There was no attempt made to access it at all.  This means that service worker functionality is not available.  Bummer.

Usually, I’ve used the cache object from a service worker script.  The use of it there was invisible to the other code that was running in the application.  But with the unavailability of the service worker the code for the presentation will show more awareness of the object.  Not quite what I would like, but I know know that is one of the restrictions in which I must operate.

The Caches object is usually used by a service worker.  But the object can be used by the window, while it is defined as a part of the service worker spec, there’s no requirement that it be only used by it.

The next thing worth trying was to manually cache something and see if it could be retrieved.

if(!window.caches)
return;
window.caches.open(‘cache1’)
.then(function (returnedCache) {
cache = returnedCache;
});

This doesn’t actually do anything with the cache yet.  I just wanted to make sure I could retrieve a cache object.  I ran this locally and it ran just fine.  I tried again, running it on the BrightSign player, and got an unexpected result, window.caches is non-null, and I can call window.caches.open and get a callback.  The problem is that the callback always receives a null object.  It appears that the cache object isn’t actually supported.  It is possible that I made a mistake.  To check on this, I posted a message in the BrightSign forum and moved on to trying the next storage option, localStorage.

The localStorage option didn’t give me the results that I expected on the BrightSign. For the test I made a function that would keep what I hoped to be a persistent count of how many times it ran.

function localStorageTest() { 
    if(!window.localStorage) {
        console.log('local storage is not supported' );
        return;
    }
    var result = localStorage.getItem('bootCount0') || 0;
    console.log('old local storage value is ', result);
    result = Number.parseInt( result) + 1;
    localStorage.setItem('bootCount0', result);
    result = localStorage.getItem('bootCount0', null)
    console.log('new local storage value is ', result);
}

When I first ran this, things ran as expected.  My updated counts were saving to localStorage.  So I tried rebooting.  Instead of saving, the count reset to zero.  On the BrightSign, localStorage had a behavior exactly like sessionStorage.

Based on these results, it appears that persistent storage isn’t available using the HTML APIS.  That doesn’t mean that it is impossible to save content to persistent storage.  The solution to this problem involves NodeJS.  I’ll share more information about how Node works on BrightSign in my next post.  It’s different than how one would usually use it.

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Brightsign: An Interesting HTML Client

Of the many HTML capable clients that I’ve worked with, among them is an interesting family of devices called BrightSign Media Players (made by Roku). One of the things that they do exceptionally well is playing videos.  They support a variety of codecs for that job and it’s easy to have them go from one video to another in response to a network signal, a switch being pressed, or a touch on the screen. I’m using the XT1143 and XT1144 models for my test.

For simple video-only projects, the free tool BrightAuthor works well.  But the scenarios that this is best fit for seem to be scenarios with relatively low amounts of navigation complexity.  For projects with higher amounts of navigational complexity or projects that require more complex logic in general, an HTML based project may be a better choice.

After working on a number of HTML projects for BrightSign, I’ve discovered some of the boundaries of what can and can’t be done to have a different shape than on some other platforms.  I have seen that there are some things that while taxing to other devices, work well on the BrightSign players; and other things that don’t work so well on BrightSign that will work fine on other players.

The BrightSign HTML rendering engine in devices with recent firmware is based on Chromium.

BrightSign Firmware Version Rendering Engine
4.7-5.1 Webkit
6.0-6.1 Chromium 37
6.2-7.1 Chromium 45
8.0 (not released yet) Chromium 65

You can encounter some quirky rendering behaviour if you are on a device with an older firmware version.  At the time that I’m writing this the 8.0 firmware isn’t actually available (coming soon). I’ve found that while the device can render SVG, if I try to animate SVG objects, then performance can suffer greatly.  It is also only possible to have no more than two media items playing at a time (audio or video).  If an attempt is made to play more than two items, then the third item will be queued and will not begin to play until the previous two complete playing.

Rather than spend a lot of time developing and testing something in Chrome before deploying it to a BrightSign, it is better if you start off testing your code on the BrightSign as soon as possible.  The normal deployment process for code that is to run from the BrightSign is to copy a set of files to an HTML card, insert it into the BrightSign, reboot it, and wait a minute or two for the device to start up and render your content.

Compared to something being tested locally ,where you can just hit a refresh button to see how it renders, this process is way too long.  A better alternative, if your development machine and BrightSign are on the same network and sub-net is to make a BrightSign presentation that contains an HTML widget that points back to your development machine.  You’ll need to have a web server up and running on your machine and use the URL for the page of interest in the BrightSign presentation.  You will also want to make sure that you have enabled HTML debugging.  This is necessary for quick refreshes of the page.

When the BrightSign boots up, if everything is properly configured you should see your webpage show up.  You’ve got access to all of the BrightSign specific objects even though the page is being  served from another page.  You can inspect the elements of the page or debug the JavaScript by opening a Chrome browser on your development machine and browsing to the IP address of the BrightSign, port 2999.  Note that only one browser tab instance can be debugging the code running on the BrightSign.

The interface that you see here is identical to what you would see in the Chrome Developer Console when debugging locally.  If you make a change to the HTML, refreshing the page is simply a matter of pressing [CTRL]+[R] from the development window.  This will invoke a refresh on the BrightSign too.

I’ll be working on a BrightSign project over the course of the next few weeks and will be documenting some of the other good-to-know things and things that do or don’t work well on the devices.

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‘texture’ : no matching overloaded function found

I ran into this error when I was trying to use the same shader across different environments; it worked in most environments but was giving me problems in WebGL on Chrome 72. The source of the problem was that my environments were using different versions of GLSL.  In some environments I needed to use the texture() function. In some others I needed to use the texture2D() function. To keep compatibility across both environments I added a simple define at the beginning of my script.

#if __VERSION__ < 130
#define TEXTURE2D texture2D
#else
#define TEXTURE2D texture
#endif

 

 

 

Is it Really a Hologram

Photography and Holography, A Brief History

I was having a discussion  about some recent articles from a few blogs. The articles were speaking of what they labeled as holograms. But some of the articles didn’t actually have anything to do with holography despite their stated subjects. The question came up “What is a hologram.” I think the answer to that question can be better understood by contrasting it against photography and a brief presentation of the differences of the principals of the two technologies.

Development of Photography and Optics

As with many technologies the contributions that led to photography were developed by incremental discovers and developments over a long period of time. Principals of photography were developed well before those of holography. One of the earliest devices related to photography was the camera obscura (Latin, camera meaning chamber or room, obscura meaning dark). When we think of cameras now we typically don’t think of rooms in a building. The usage of many words change over time and our usage of the word camera today evolved from this usage. A camera obscura can refer to a room or a box with light blocked off except for a single hole through which light is allowed to enter. An upside down image of the scene outside the room is projected on the wall to the opposite of the hole. The earliest known writings that mention such a device are found in the writings of the philosopher Mozi. Mozi asserted from the camera obscura that light travels in a straight line. His followers developed an optic theory based on this.

Camera Obscura Picture

Image Credits: Wikipedia

There had been two prevailing theories of how vision worked. The emissions theory of vision hypothesized that the eyes emitted something and that we were able to see these emissions had to collide with the object being perceived. It was supported by people such as Ptolemy and Euclid The intromission theory of vision (supported by Aristotle) hypothesized that physical forms of the object were entering one’s eye. Around 1011 – 1020 C.E. the “Book of Optics” was written by Alhazen. His was that from an illuminated object light of different colors would travel from the object in every direction. Thought experiments with lenses and mirrors he developed a more complete theory on how light travels. He could not answer the question of how that light formed an image on an eye. Kerplar addressed the question of how images form. Kerplar also saw the human mind as playing an active role in the perception of images.

It had already been known that exposure to light would change the color of certain substances. During the year 1727 in German Johann Heinrich Schulze published the results of experiments that showed that the darkening of silver salts was due to exposure to light. The first person to capture images with through such a process was Thomas Wedgwood. But his images were less than permanent as they would fade with further exposure to light. It wasn’t until 1826 that Joseph Nicéphore was able to create the first permanent image. He used a camera obscura with a eight hour exposure time through a process he called heliography (Greek, helio from sun and -graphy from writing/message. Joseph Nicéphore partnered with Louis-Jacques-Mande Daguerre to improve the process and carried on with the work on improving the contrast after Nicéphore’s death. Henry Fox Talbot had independently developed a process for fixing silver salts only to find that Daguerre had accomplished this before him. Nevertheless he sent a paper to the Royal Institution titled “Some Account of the Art of Photogenic Drawing.” In his process a negative image was captured and that negative image was later copied to a positive image. By contrast for the daguerreotypes direct images were created. The images from daguerreotypes were sharper, but the production of the negative for Talbot’s two step process allowed unlimited positive images to be produced from the negative. The first daguerreotypes camera was produced in 1839.

Early Daguerreotype camera

Image Credits: Wikipedia

With the process improvements instead of an exposure that lasted for hours in a dark room exposures took minutes for a portable box. Instead of a shutter a lens cap was removed from the front of the device. As film became more sensitive exposure times were reduced from minutes to seconds. A mechanical shutter was added to better control exposure times. In 1885 George Eastman started producing paper film. By 1889 he changed to using celluloid film. Eastman decided to sell cameras at a loss expecting to make money back from the sales of film. The first camera was called the “Kodak.” In 1975 Kodak engineer Steven Sassonmade a camera with an electronic sensor. The images were captured at a resolution of 0.1 megapixel. He also combined the sensor with parts from a movie camera to save series of images to a cassette tape that could be viewed on a TV monitor. Twenty five years later flash memory started to replace the use of film and magnetic.

Beginning of 3D Imaging

The same year that the first daguerreotype camera was produced Sir Charles Wheatstone invented the reflecting mirror stereoscope. He used mirrors at 45-degrees to to the viewer’s eyes so that each eye would see a slightly different drawing. Through binocular depth perception the two images were experienced by the person as a single three dimensional scene.

Mirror stereoscope

Image Credits: Wikimedia

The same year David Brewster created a simple stereoscope crediting the idea to a teacher of mathematics named Elliot that is said to have come up with the idea in 1823. Brewster improved upon the stereoscope concept with the lenticular (lens based ) stereoscope (also known as the Brewster Stereoscopes). Taking the design to France improvements were made on the stereoscope by Jules Duboscq with the creation of the stereoscopic daguerreotypes. In 1861 Oliver Wendell Holmes made a verion of the stereoscope that was easier to produce. Patend in 1939 was the View-Master Stereoscope. In 1950 a device titled the “Sensorama” was created designed to present stereoscopic motion pictures, smells, feelings, and sound. About the same time Douglas Engelbart (inventor of the mouse) was experimenting with using screens as input and output devices. In 1968 the first system that would be describe in modern terminology as “augmented reality” was created by Ivan Sutherland and Bob Sproull. It was heavy and the headset had to be suspended from the ceiling. The graphics it displayed were wire frames.

Viewmaster: one version of a Stereoscope

View Master Image Credits:Wikimedia

Holmes Stereoscope

Holmes Stereoscope Image Credits: Wikimedia

Development of Holograms

The development of holograms occurred much more recently in history. In 1947 Dennis Gabor developed holographic theory. His efforts were to improve the quality of images from electron microscopes. In electron holography a subject is placed in a diverging electron beam (This would be a good place to talk about Quantum coherence, or it may be bad to talk about it at all).. Electrons that are scattered by the object and electrons undisturbed by the object both strike a detector and create an interference pattern with each other. An image of the object is constructed by this interference pattern. Holograms made with light didn’t occur at the time in part because of the properties of available light sources. Many light sources emit light that falls across a spectrum of wavelengths (colors) and are not a single pure color. It wasn’t until 1960 that such a light source became available through the work of N. Bassov and A. Prokhorov, and Charles Towns with the development of the laser. Light emitted from a laser has two important properties that are vital to making holograms. The light is monochromatic (a single pure color) and the light is coherent. One might wonder if single color light is needed why not add a color filter to a light bulb. Most light filters will reduce but not necessarily completely eliminate the other wavelengths of light. It’s also not coherent. (note: LED lighting achieves being monochromatic without being coherent).

Components of original Ruby Laser

Components of original Ruby Laser. Image credits Wikimedia.

I really don’t like this explanation. I need to work on this Understanding light coherence requires a bit of knowledge of the wave-particle duality of light. Those that performed the double-slit experiement in a physics class may remember discussing this. Consider ripples on the surface of water from a pebble being dropped in. If you could view a cross section of one of the waves you’ll see the ripples form crests and troughs. If two pebbles are dropped in close to each other at the same time waves will emanate from two spots and overlap and interfere with each other. There will be areas where two crests coincide together forming an even higher crest (constructive interference). There will be areas where two troughs coincide forming a lower trough (constructive interference). And there will be areas where a trough from one wave and a crest from the other coincide resulting in the water being at the same level it was at before there were any waves (destructive interference). The distance between corresponding parts of the wave (ex: from one crest to another) is the “wave length.” The number of crests or troughs that occur over some period of time is the wave frequency. This same principal occurs with sound waves. Noise cancelling headphones use destructive interference to reduce the intensity of the sound-waves reaching the ears of those wearing them. The same principal is also applicable to light. Most normal light sources

One process for producing light holograms is similar to that of electron holography. Instead of using a detector being hit with undisturbed and scattered electrons a detector is hit with undisturbed and scattered particles of light (photons). The detector is a holographic plate. Because slight movement of the subject being holographed, the light source and optics, or the holographic plate would change the interference pattern it’s necessary for all of these parts to be absolutely still when the “image” is being made. After the exposure of the holographic plate it can be fixed/developed so that further exposure to light won’t damage recording.

Looking at an object through a hologram is like looking at an object through a window. If you took a hologram and broke it in half it doesn’t prevent you from being able to see the hologram. It’s analogous to reducing the size of the window through which could look by painting over part of it. While you can still see outside the number of angles from which you can view the scene is reduced. If you move your head to the left or right your perspective of the objects holographed will change which contributes to the perception of depth. Each observer of a hologram will see it from her own perspective. Each eye having it’s own perspective provides the stereoscopic depth queue.

Is it Really a Hologram

20190301_222726.jpg

Returning to the discussion that inspired this entire post, when I was commenting on an article I was surprised that the article that mentioned holograms in it’s title was actually about holograms. Most articles I’ve come across mentioning holograms are not about holograms. What about the Hololens? It is described as being “the first fully untethered, holographic computer, enabling you to interact with high‑definition holograms in your world.” Are these really holograms? No, they are not holograms in the same sense as the word is used in holography. Computer based systems are full of terms and names that have been borrowed from other items and concepts. We often use these terms without thinking much about them. An audio streaming application isn’t really a radio. The root graphical interface on my computer isn’t really a desktop. There’s a long tradition of adopting terms as a metaphor. After those terms are used long enough they they come to denote the item for which they have been used. Internet radio isn’t radio, but it may have some of the experience of using a radio. The root graphical interface of some computers has been called the “Desktop” for 34 years at the time that I”m writing this. Similarly the images viewed through the Hololens are not from holography. But there are elements of the experience of viewing a hologram that one has with the Hololens. If you move your head from left to right the perspective of the object changes. There are several perceptual depth queues experiences including the images being stereoscopic, parallax, and perspective transformations of the object represented. The use of the word seems to communicate well what to expect from the experience; the presence of an image with depth.