Author Archives: Eric

Visual Treats

I usually end each “7 Things” post with a lighter item. Having beaten through my backlog of resources, there are a bunch of visual links left over. So, here’s a post of pure fluffy desserts. All images are clickable for more information.

First, camels:

and zebras:

These are now a part of the “Too True to be Good” gallery.

3D fractals:

More information about these on Geeks3D.

Crayola’s Law is that the number of crayon colors doubles every 28 years:

I just plain liked this animated Sierpinski triangle someone used as a profile image (thanks, Evan):

Nice concept, the equations of art:

Here’s an art something (not embedded here, you actually have to click), but I don’t have the OCD needed to see the image hidden.

Perhaps not massively visual, but amazing nonetheless, various prime number calculators run using the Game of Life. Here’s the Mersenne prime generator:

I’m starting to believe everything can make a pixel. Here’s coffee:

And rice plants (thanks, Doug):

For a finish, here’s a history of 100 years of film VFX in five minutes:

Well, wait, there’s one more thing… Naty and I love the realistic CG in this piece, The Third & The Seventh. I’m not going to embed it here; follow the link and definitely watch it fullscreen. More amazing still, it’s the work of one guy, Alex Roman. The only elements that are not CG are the photographer, the pigeons, the time-lapsed sky and growing flowers, and the jet. There’s a compositing breakdown video of various scenes, showing the techniques used. That said, Naty likes it but for my tastes it’s pretty boring to watch for more than half a minute, as most CG demos are (jaded? Maybe; mostly, I just like plot).

If your interest wanes, skip to 8 minutes in (well, you can’t skip ahead with Vimeo; just let it load and come back later). Perhaps that’s the best way to appreciate the clip: play it as a loop and look at it now and then, in small doses. There’s a heavy hand with the focus/depth-of-field effect at times, but in one sense I do like seeing this effect overused: it’s like watching CPU cycles burn before my very eyes, knowing how much the algorithm costs. Last niggle (and I should probably be soundly thrashed with a riding crop for noting these things, but it stuck out for me): the wind turbines turn backwards. Quibbles aside, the images here are so much better than any I will ever make that I’m a total admirer of it on the “technical chops” and “incredible dedication” levels.

7 Things for February 10

  • The first three are from Geeks3D, which is a worthwhile site I frequently reference. First: some noise textures, in case you don’t feel like making some yourself.
  • Next, a night-vision filter in GLSL, developed with their GeeXLab tool for prototyping shaders.
  • Finally, PyOpenGL_Lab, which calls OpenGL from Python. Interpreted languages like Python are lovely in that there’s no compilation step, making experimentation much more rapid. If you’re a Perl person, there’s this module.
  • Daniel Rákos has an article about how to perform instance culling using the GPU, using OpenGL 3.2. The basic idea is to run the bounding volumes through the geometry shader for frustum culling and pipe out results as transform feedback, which is then used in a second pass for which instances to actually render. This type of technique has been done using DirectX (e.g., Froblins), Daniel shows how to do it in OpenGL and provides source.
  • Aras Pranckevičius has a worthwhile post on deferred rendering and mipmap bugs, along with some good follow-up comments.
  • John Ratcliff’s Code Suppository has lots of little handy graphics code tidbits and chunks. It’s moving here and here on Google Code, but the original page is much easier to skim.
  • Wolfgang Engel provides a nice little page of books and resources he recommends for upcoming graphics programmers, with some good follow-up comments. I hadn’t heard of the 3D Math Primer before. It gets high ratings on Amazon, and you can use Look Inside. Skimming it over, it does look like a good book, covering many topics with the space they deserve (vs. our sometimes quick zoom through them in our own book). Code snippets are also given throughout. The book mentions “The First Law of Computer Graphics,” but unfortunately the pages explaining it are blocked. Happily, I found it on Google Books: “If it looks right, it is right”. Whew, good, I honestly was concerned there was some law I had been breaking all these years.

… and I’m all caught up, my queue is empty! Well, there will be a special post tomorrow.

7 Things for February 9

Some news, and some olds.

  • HPG has a CFP. In slow motion,  this means the High Performance Graphics conference, June 25-27 in Saarbrucken, Germany, has a call for participation. Naty talked about this conference in his post two months ago; now the HPG website and CFP are up. In case you don’t recognize the conference’s name, this is the combination of the Graphics Hardware and Interactive Ray Tracing symposia. HPG was fantastic last year, with more useful (to me) papers than SIGGRAPH (where it was co-located). Potential submitters please note: because HPG 2010 is co-located with EGSR this year, the deadlines are very tight after SIGGRAPH notification and quite rigid. In other words, if your SIGGRAPH submission is rejected, you will have a very short time to revise and submit to HPG (i.e., by April 2nd).
  • NVIDIA has put up a list of talks at GDC in which it is participating, which will undoubtedly appear soon after on the web. In other NVIDIA news, there’s an interesting press release about NVIDIA and Avatar and how GPUs were used in precomputation of occlusion using ray tracing, for scenes with billions of polygons.
  • A handy tool for showing frame rate and capturing screenshots and video that is worth a mention again (it’s buried on the Resources page): FRAPS. It’s been around forever, continues to improve, and the basic version is free.
  • Crytek made an updated version of the famous Sponza model (used in many global illumination papers) available in OBJ and 3DS Max formats, along with textures. If you have the time, in theory 99 lines of code will make a picture for you.
  • Stefan Gustavson has a nice little demo of using distance fields for “perfect” text rendering. This type of technique has been used for a number of years in various games, such as Valve’s Team Fortress 2. The demo unfortunately falls apart when you rotate the scene off-axis, but otherwise is lovely.
  • SUBSTANCE is an application for making 3D evolutionary art. I really need more time on my hands to check this sort of tool out…
  • Theory for the day: we don’t have fur because our skin can show our emotions, which we pick up with our improved color perception.

New Books and Reworked Books Pages

We’ve been reworking our books page to take longer to download, I mean, to be more visually interesting and readable. Honestly, the old one was a dense, hard to view pile of book titles. Just adding whitespace between titles is a plus. We’ve also added one book to the recommended list, Eric Lengyel’s math book. Anyway, go check it out. On our main resources page we’ve put all the free books online into one section.

There are some new books coming out that look interesting. For those of you going to GDC, there should be some worthwhile offerings to check out on the floor.

The Programming Massively Parallel Processors book by Kirk (Chief Scientist at NVIDIA) and Hwu (professor at U. of Illinois) is out by now, as of 3 days ago, and is currently sold out on Amazon. It’s undoubtedly derived from the course they co-taught at Illinois. CUDA and Tesla are the keywords here. Hwu’s current course lectures are here and here; I don’t know how they compare to the book, but these newer (non-Kirk) lectures seem more general. I look forward to learning more about this volume—if you have it, please do leave a comment (or better yet, a review on Amazon).

Wolfgang Engel and all have a new book out, GPU Pro. He’s using a new publisher, so it does not have the ShaderX name, but effectively is ShaderX 8. Finally, the book is color throughout vs. previous ShaderX’s. I’ve skimmed some of the articles, and it’s in the same vein as others in the series: a range from practical advice to wild ideas. I can just about guarantee that professional interactive graphics programmers will find something of interest—I found about 5 articles off the bat I want to read through, and plenty of others I should at least skim. More info at the blog for this book.

Game Programming Gems 8 adds to this long-lived series. I haven’t seen it yet, so no comments; Adam Lake’s blog may give updates on status, contents, etc. This series has slowly drifted to including much more non-graphical material over the years. Understandable, but Adam’s someone I think as a graphics guy, so I’m selfishly hoping for more graphics and less the other stuff. My view on collection books like ShaderX and this is simple: an hour of a programmer’s time is about the same as the cost of a book, so if the book saves an hour, it’s paid for itself. Of course, there’s the time cost of reading the articles of interest, but still…

Second editions have been announced for Physically Based Rendering Techniques and High Dynamic Range Imaging. PBRT is more offline rendering oriented, but is a great book because it takes a stand; the authors say what they do for a real system and why they made that choice, vs. listing all possible techniques. It also presents about the longest literate programming presentation published. I have a short review of the first edition. The HDRI book is nice in that it pulls together the various research articles out there into one place, with a coherent thread to it all. The second edition’s new material is described on its Amazon page.

7 Things for February 8

I use a LIFO stack for these link collections, so we’re starting to get into older news. Olds? Still good stuff, though.

  • I hadn’t noticed this set of notes before from Valve, “Post Processing in the Orange Box.” It’s about sRGB (think, gamma correction), tone mapping (think, rescaling using the histogram), and motion blur (think, types of blur). Interesting that a variable frame rate combined with blur made people sick. They’d also turn blur off if a single frame was taking too long. (from Morgan)
  • Wolfgang Engel has posted DirectX 11 and DirectX 10 pipeline overview charts. In a similar vein, Mark Kilgard has a talk about the changes from OpenGL 1.0 to 3.2 with some worthwhile data flow diagrams and other material.
  • openSourceVFX.org is a catalog of open source projects that are particularly suited for film visual effects and animation work. It is maintained by professionals in the field, so the resources listed are those known to actually be used and production-worthy. (thanks, Larry)
  • Here’s another PhysX demo, of water—a little jelly-like (good spray is hard, since it’s so fine-grained), but pretty amazing to see happen at interactive rates.
  • One resource I didn’t recall for my blog entry about tools for teaching about graphics and game creation: Kodu, from Microsoft. For grade schoolers, it uses a visual language. Surprisingly, it’s in 3D, with a funky chiclet terrain system. For still more tools, check the comments on the original blog entry—some great additions there. (pointed out by Mark DeLoura)
  • Another interesting graphics programming tool is NodeBox 2, now in beta. It uses a node graph-based approached, see some examples here.
  • The story of Duke Nukem in Wired is just fascinating. We all like to tell and listen to stories, so it’s hard to know how true any narrative is, but this one seems reasonably on the mark. A little balance is provided by Raphael van Lierop.

7 Things for February 7

Comin’ at ya, lots of one-liners, vs. yesterday’s verbose posting.

7 Things for February 6

With the excitement of Ground Hog’s Day and James Joyce’s birthday over, it’s time to take off the silly paper hats and get back to writing “7 things” columns. Here goes:

  • Jeremy Shopf gives a nice summary of recent ambient occlusion papers. AO is becoming the new Shadows—every conference must have a paper on the topic. Honestly, it’s amazing that some of these ideas haven’t popped up earlier, like the line integral method. If you accept the basic approximation of AO from the start, then it’s a matter of how to best integrate the hemisphere around the point. I’m not downplaying the contribution of this research. Just the opposite, it’s more along the lines of “d’oh, brilliant, and why didn’t anyone think of that earlier?” The answer is both, “because those guys are smart” and, “they actually tried it out, vs. thinking of an idea and not pursuing it.”
  • Thinking about C++ and looking at my old utilities post, I realized I forgot an add-on I use just about every day: Visual Assist X. This product makes Visual Studio much more usable for C++. Over the years it’s become indispensable to me, as more and more features get integrated into how I work. I started off small: there’s a great button that simply switches you between the .cpp and .h version of the file. Then I noticed that other button which takes a set of lines I’ve selected and comments them out in a single mouse press, and the other button that uncomments them back. Then I found I could add a control that lets me type in a few characters to find a code file, or find a class. On and on it goes… Anyway, there’s a free trial, and for individuals it’s an entirely reasonable (for what you get) $99 license. By the way, you really don’t need to get the maintenance renewal every year.
  • As you may know, MIT has had a mandate for a number of years to put all of its courses online in some form—there are now 1900 of them. The EE & CS department, naturally enough, has quite a selection. The third most visited course on the whole site is Introduction to Computer Science and Programming, from Fall 2008 (and I approve: they use Python!). There’s only one computer graphics course, from 2003, but it covers unchanging principles and concepts so the “ancient” date is a minor problem.
  • Naty pointed out this article about deferred rendering. He notes, “A nice description of a deferred rendering system used in a demo—of particular interest is the use of raytraced distance fields for rendering fluids, and the integration of this into the overall deferred system.”
  • A month and a half ago I listed some articles about reconstructing the position or linear z-depth in a shader. Here’s another.
  • It’s the ongoing debate, back again. No, not dark vs. milk chocolate, nor Ferrari vs. Porsche, but DirectX vs. OpenGL. My own feeling is “whatever, we support both”. By the way, the upcoming book GPU PRO (which also has a blog, and has just been listed on Amazon) includes an in-depth article on porting from DX9 to OpenGL 2.0. Mark Kilgard’s presentation also discusses the differences, including the coordinate space and window space conventions.
  • I love human pixels. The Arirang Festival in North Korea is a famous example, check out Google Images. But that’s just a card stunt, impressive as it is. This video shows a technique I hadn’t seen before (note that some of it is sped up—check the speed of the people on the field—but still fantastic). There are other videos, such as this and this.

C++, Baby

I was catching up on the Communications of the ACM, and noticed this article, Computer Science in the Conceptual Age. The “catch your eye” text on one page was: “Programming interns/job seekers from our program Spring 2009 (35 interviewed in the game industry) found no companies administering programming tests in Java.”

There are other chewy bits, such as: “The USC experience is that 100% of its students interviewed for programming positions are given three-to-four-hour-long programming tests, with almost all companies administering the tests in C++.”

Also, this: “The game industry will also tell you that it wants the first four programming classes in C++, not Java, according to M.M. McGill and my own private communications with directors of human resources in major game-development companies.”

One final morsel: “Many game companies say they will not interview or hire someone whose first programming language is Java.”

Wow, that last one’s harsh, especially since my experience with two teenage sons (one in high school, the other a freshman computer science major) is that Java is the norm for the first “real” language taught (I don’t count Scheme as a real, “you’ll get paid programming in it” type of language). I don’t think I’d rule someone out for knowing Java first, though having gone from C++ to Java and then back, the transition from Java to C++ is like being thrown out of the promised land: you suddenly again spend half your time messing with memory in one form or another. C# and Java are darn productive in that way. And, no, for me at least, those auto-pointer classes in C++ never quite seem to work—they need a different sort of discipline I don’t appear to have. I also love that my first Java program, from 1997, still works on the web; some of my C++ programs from back then won’t run on Vista or Windows 7 because the WinG DLLs are not a part of those operating systems (thanks, Microsoft).

Nonetheless, the article’s right: at Autodesk we’ve dabbled with Java and C#, I’ve seen Python used for UI control around the fringes of a program, but the heart of client-side graphical programs is almost always C++ (or isn’t, with regrets and cancellation often soon following—been there myself, though Java was only a little bit to blame, to be fair). Also, XNA, which uses C#, does not have a 64 bit version. In addition, Microsoft’s managed code support usually lags behind the “real” DirectX, i.e., the one for C++.

Looking around, I did find an open-source project, SlimDX, that does support 64-bit assemblies for interfacing with DirectX. Interestingly, they claim one AAA game title shipped using SlimDX, but no mention of which. So I asked. They’re keeping the information confidential, which is fine, but the other comment sounds about right: “The large majority of professional commercial PC/console games are still developed in C++ because of the sheer amount of legacy code the studios developing those games have that is already in C++ (and because of the generally poor support from major console vendors for languages other than C or C++, which contributes to lock-in).”

Long and short: it’s C++, baby.

Tools for Teaching

Today’s question: what tools are there for teaching about computer graphics and/or computer games? I don’t have a definitive answer, but I have a little experience with a few resources and know of others. That said, I haven’t sat down with more than two of them for any serious amount of time. Comments are most welcome, especially for pointers to better overviews than this!

I’ll list these roughly from the more basic to those for budding programmers and indies. That said, I think some languages, e.g. Processing, are easier to get into than the UI-driven systems, but some understanding of programming is needed. I’ve also ignored some famous examples like Logo, as it feels a bit crusty and limited to me. But, that’s me—let me know if you have a great counterexample.

Game Maker: My experience with this one is trying it with my younger son, and later Cornell using it in a 20 hour digital game design workshop for high-school students. It’s much more about games than graphics, graphical elements are 2D sprites and backdrops. Most of the focus is on events and constraints, as you might guess. Very UI oriented, no programming language involved per se – the UI controls are essentially a programming language of a sort. I have The Game Maker’s Apprentice, which is good in that it gets the person involved quickly, but bad in that little understanding gets transmitted early on (“now set this UI control to do this, now load that file there, now hit ‘run’; if it doesn’t run, walk through all the instructions carefully again”). From Amazon reviews, the book Getting Started in Game Maker might be better. There’s lots of example games and web support. Cost: free Lite version and trial Pro version, cost for Pro version (which you want) is $20.

Multimedia Fusion 2: this is an expanded and rebranded version of the company’s “Games Factory 2” product that includes all its functionality. It looks similar to Game Maker, but targeted for a somewhat more professional audience (and at a higher cost) overall. That said, there is a book for it, Game Creation for Teens. Cost: free trial download from 2008, lowest street price I saw for Multimedia Fusion 2 was $83.

Flash: Adobe’s popular animation & game programming system, famously unsupported by the iPad. Back some years ago the local science center used Macromedia Flash to teach grade-school kids about basic Flash animation. Now Adobe Flash Professional CS4 is used to create Flash. From what little I’ve read, the interface is daunting, but it’s actually pretty easy for beginners to get going. Animation is something that can be done purely with graphical tools, Actionscript 3 is a language for serious interactive applications. There’s of course a huge number of books, forums, and other online support. Cost: as low as $200.

Flixel: I’ve heard this mentioned twice as a worthwhile development resource for Flash. It provides some useful base classes in Actionscript 3 for making games, along with tutorials, a forum, etc. Cost: free.

Pygame: This is the first of a few language-oriented resources. Pygame is a bunch of modules to help in writing games in Python. One friend said he got a simple game running in less than two hours from download (but that’s him…), another acquaintance wasn’t so wild about it as he hit its limitations. 2D oriented, though there’s a few 3D experiments. This sounds like a pretty good, and super-cheap (free!), way to introduce kids to programming. I recall an article in CACM or IEEE Computer a year or so ago about Python, and it made an excellent point: Python is one of those great languages that is made for people who have never programmed before. Like Perl, it provides the ability to program and get something done quick without a lot of clutter, and so is a better candidate for the first programming language taught, not Java. Let the programmer have fun getting things done, then teach them about more elaborate computer science concepts and why these are useful. Python is pretty easy to learn: Andrew Glassner has a great introductory page – in a few hours you’ll know the basics. But I digress… Anyway, Pygame has lots of users, many of the projects are open source, there’s even a second edition of a free professionally-produced book about Pygame. Cost: free.

Processing: OK, if you’re sick of hearing about game programming resources, here you go. This is a little language suited for making cool 2D images. Key basic graphics concepts—transforms, curves, image manipulation—are encapsulated. Basic interaction is also a snap. It has a 3D component, but that part is fairly weak. I’ve played with it, it’s fun. Not meant for games; nonetheless, it’s possible. Much online support, and there are two popular books, here and here (the second has lots of additional material online). Cost: free.

Blitz Basic: I’ve heard of this one from a few people but have no direct experience. Definitely about programming, it uses BASIC, but enhanced with functions and types. It looks pretty full-featured, e.g. there’s joystick and networking support. BlitzPlus is the Windows 2D version, BlitzMax also runs on Macs and Linux, Blitz3D adds 3D support: camera, lighting, texturing (including bumps), CLOD terrain, etc. There’s an SDK for interfacing the 3D engine with C++, C#, etc.  Manuals are online, and there looks to be a healthy user community. There’s a German version of the website. Cost: free trials of all, prices range from $60 to $100 per product, with more for add-ons.

XNA: This is something of the 800-pound gorilla for programming-related graphics education. As an example, some teen programmers in the Cornell workshop were using XNA as the next step beyond Game Maker. A Microsoft initiative, it’s partially aimed at students and hobbyists. The base language is C# (Java on steroids, if you haven’t used it). There are lots of element and audiences for XNA, Wikipedia also covers the area well. There are many XNA resource sites and books out there (though I was sad to see Ziggyware is no more). Cost: free for the most part, depending on what you’re doing.

Ogre: Begun about a decade ago, this is from all reports a pretty nice graphics engine. It supports a huge number of effects and areas (I know developers who have consulted the codebase for ideas). There are lots of add-on libraries. It’s great for deep-down serious graphics education; Ogre is entirely open source (MIT license), so everything can be examined. Cost: free, and free licensing.

Unity: You’ve now definitely entered the Indie game developer zone. A 3D games development system I’ve heard mentioned by others as a way of learning. Multiplatform, now including the iPhone. Cost: free base version and trial of Pro version, which costs $1499; other pricing for iPhone version. There’s a book. Licensing for Indies has become free.

UDK: The Unreal Development Kit is the most popular game engine used for game development. Cost: free to download full version, 530 Mb of fun. Licensing cost: if you have to ask, you can’t afford it.

Torque: Torque is the second most popular development platform for game creators. For Torque, two versions exist, 2D and 3D. Three books are available on this engine. Cost: $250 for 2D, $1000 for 3D version, but educational pricing can be arranged.

Whew! OK, what did I forget? (Make sure to read the comments—some excellent additions there.)

Update 2/6/2010: Kodu, from Microsoft. For grade schoolers, it uses a visual language. Surprisingly, it’s in 3D, with a funky chiclet terrain system. Another interesting graphics programming tool is NodeBox 2, now in beta. It uses a node graph-based approached, see some examples here.

You May Want to Own Your Own Images

Now that the SIGGRAPH 2010 paper deadline is over, I thought it worth mentioning ways in which you can retain full use of your own images, should you be fortunate enough to have your work accepted for publication. This isn’t meant as an “ACM’s copyright policy is bad” article, rather it presents some possible workarounds while waiting for the policy to be improved. Think of these ideas as code patches.

A number of graphics people were talking about the ACM’s copyright policy. James O’Brien wrote:

I also am bothered by the fact that ACM claims to own images used in a publication. For example, if I render an image and use it to illustrate a paper, ACM now claims to own the copyright on the image and I am limited in what I can use that image for in the future. I’d like included images and other non-text content to be treated similarly to how 3rd party images are currently treated so that the authors retain copyright to the images and only grant ACM unlimited permission to use.

Larry Gritz replied:

James, why are you more bothered by “I painted the image, now they claim ownership” than “I wrote the words, now they claim ownership”? Aren’t they essentially the same situation?

James responded:

Not really, at least not to me. The images often represent a huge amount of work to demonstrate some algorithm. The words I wrote in an afternoon and I can always write some more words that say roughly the same thing if I had to. The images also have uses beyond the paper. For example, if “Time” magazine writes an article about me, they will want to run the images, or if a textbook author decides to talk about my algorithms s/he may want the images to illustrate the book. I also don’t see the argument for why ACM would benefit by owning the images. It’s a case where it costs the author something but gains ACM nothing, so why not change the policy to maximize everyone’s benefit?

—

In further discussions, we identified a few different ways to be able to use your own images. Mine is one that was first mentioned in the Ray Tracing News in 2005:

My advice (worth exactly nothing in court) to anyone publishing nowadays is to make two images of any image to be published, one from a fairly different view, etc. In this way you can reuse and grant rights to the second, unpublished image as you wish. That said, there’s an area of law where you compare one photo with another and if they match by 80% (by some eyeballing metric), then they’re considered the same photo for purposes of copyright. Usually this is meant to protect one photographer’s composition from being reused by another. What it means to 3D computer graphics, where it’s easy to change the view, etc., remains to be seen. Still, ACM’s rights to your work are less clear for a new, different image. This sort of thing is small potatoes, but taking action so that you have images and videos you fully own then removes the hassle-factor of granting permission to others wanting to use your work.

James O’Brien said the following:

I’ve bumped into this copyright issue with images a few times. The first was when a book author wanted to use an image of mine in her text. I said yes, but she was subsequently told by ACM that she needed ACM’s permissions and she had to pay a fee and include a notice crediting ACM rather than me.

If you are willing to be persistent, you can keep ownership of your copyright for your whole paper and just grant ACM unlimited permission. I did this in 2005 and if you download “Animating Gases with Hybrid Meshes,” SIGGRAPH 2005, from the DL you will see the copyright notice says “copyright held by author”. That was inserted by them instead of the regular notice after several days of discussion on the phone. It was very unclear what the motivation was for the ACM to insist on owning the images.

If the images are owned by a 3rd party they can only ask you to get permission. After 2005, I did a few papers where I included a note that the images were all copyright by UC Berkeley and used with permission. It’s not clear if that sort of note means anything.

The latest version of the ACM copyright form I’ve seen requires you to fill out an addendum listing 3rd-party-owned components and you have to get a separate permission form for them. My paper in SCA this summer required this form (images owned by Lucas Arts). It was a hassle to get Lucas to sign off on the permissions. But that’s not ACM’s fault… in fact Stephen Spencer was very flexible.

An anonymous person wrote:

Another option would be for people concerned about this to set up an organization, call it Digital Images LLC, that you assign the copyright to as soon as you generate the image. (That will likely require the permission of your university or employer, since the image is arguably a work-made-for-hire under the copyright law and therefore owned by the employer.)

Digital Images LLC then licenses its copyright in the images so that you can use it in papers, books, or other works. As far as ACM is concerned, it’s just like if you used a figure from another source with permission. The ACM policy makes that clear:

The author’s copyright transfer applies only to the work as a whole, and not to any embedded objects owned by third parties. An author who embeds an object, such as an art image that is copyrighted by a third party, must obtain that party’s permission to include the object, with the understanding that the entire work may be distributed as a unit in any medium.

—

So, there are at least three ways where you can retain full rights to your own images. Mine is “make another”, James’ is “request an exception”, and there’s finally “create an LLC”. If you have another, have information about the use of any of these, or just plain have an opinion, please comment.