Blog Archive

Viewing page 4 from August 07, 2012\ to June 27, 2013\ .

Nginx May Cut You Off Early

How the default configuration bit me.

I very recently launched shadowsinthegrass.com, a crowd-funding website for a short film I am working on. As a donator, you are able to upload an avatar to be presented with your credit. I had limited the file size to 2MB... or so I had thought.

Underneath, the site is built with Flask, served with Gunicorn, and behind an Nginx reverse proxy.

Unfortunately, I received reports that some uploads were failing and reported as "Error: undefined" to the user. Strangely, it didn't seem to be an error in the Python app, as I was not receiving any tracebacks when this error occurred.

It turns out that Nginx has some default configuration that I wasn't expecting.

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My Report Card

The second GitHub Data Challenge recently finished, and GitHub just announced the winners.

The first place went to The Open Source Report Card, which generates an English prose summary of your GitHub activity (from January to March 2013), and provides some charts to back it up.

My report card for that period is somewhat eerie (to me):

Mike is a serious Pythonista (one of the top 13% most active Python users) who loves pushing code. Mike is a nine-to-fiver who seems to work best in the mid-afternoon.

[...]

It seems—from their activity streams—that Mike and westernx are probably friends or at least virtual friends. With this in mind, it's worth noting that westernx is less foul mouthed

I would love to see a chart about my tendency to swear in commit messages.

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RenderMan Textures from Python

In order to better understand the guts of Python and RenderMan, in the past I have implemented a number of proof of concept projects extending or embedding each. Previously, I combined my efforts by embedding Python into RenderMan as an RSL shadeop so that shaders could be written in Python!

Unfortunately, that code is lost to the ages, so I decided to revisit my efforts and produce something that could actually have applications: using Python as a source of texture data for RenderMan.

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Anatomy of a Maya Binary Cache

DAGs all the way down.

On a limited number of occasions I have had need to reach directly into some of the raw files produced by Autodesk's Maya. There isn't much documentation I could find on the web, so I will try to lay out what I have learned here.

The generic structure is based on the IFF format, but with enough small changes to warrant this exploration (with lots of kudos to cgkit's implementation, which helped with some of the gritty details).

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Resources for Learning Python

We can do this the hard way, or the easy way...

I am often asked my opinion on how to get starting with programming, and usually with Python in particular. I usually outline three different routes that must be taken: learning how to work with Python, learning best practises for Python, and reading lots of good code from others.

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A Pool of Shotguns

A transparent connection pool for the Shotgun API in heavily threaded environments.

I have been working very heavily with Shotgun for the last several months, creating much deeper integrations between it and Western X's pipeline.

One of the things that bit me pretty early on is that the official Python API for Shotgun can not make parallel requests.

Under most conditions this isn't a big problem; the underlying connection would just serialize my threads' access to the Shotgun server, adding some latency, but it wasn't too bad. What was very irritating, however, was that a particular version of Python on OS X 10.6 would occasionally segfault during parallel requests. It took quite a few days of debugging Python in GDB (not a particularly easy prospect, especially since the problem was hard to reproduce) to isolate the problem to a bug in the ssl module's use of zlib to compress the request before sending it to the server.

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SIGGRAPH 2012 - Day 5

Until Next Year

This happened to me last year as well, and similarly with the smaller Vancouver SIGGRAPH events in the past few months, in which I lose perspective in the massive sea of expensive blockbuster film work:

We have gotten to the part of #siggraph where I develop a persistent rage for not being involved in enough awesome things. #neverenoughtime

@mikeboers on . Visit on Twitter.

However, perspectives need to be kept in check. My short, Blind Spot, has been doing rather well lately, getting into yet another festival (I think that is 6 now), and the VFX of that film was the result of only two people working in their spare time.

But for now the plan is to feed off of the helpful part of my rage and do the best job I can do, both at work, and independently. I'll be back next year, hopefully knowing a few more of you and having a slightly larger influence on the industry and presented works.

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SIGGRAPH 2012 - Day 4

On Massive Projects

Sessions continued like normal, with me learning too much and inspiring me to try working with way too many of them... like normal. There was a theme that I kept hitting on this week, however, that requires some additional reflection.

My work in this industry thus far has been constrained to (relatively) small projects, mainly on episodic TV or direct to DVD movies. However, many of these sessions (not just the production sessions but also many talks and tech papers) reveal to me that the scope of these projects is at a completely different level than I am used to.

For example, I attended the ILM Battleship presentation on the 4th day in which there were a number of stats thrown around for a particularly heavy shot (the presenter said that he believed it to be the most complicated VFX shot, ever) including that it took 2-5 days per high resolution fluid sim (of which there were many), they cached approximately 20TB of simulation data, and it consumed nearly 23 years of sequential CPU time. Another was during the Disney Paperman presentation on the 5th day in which the director talked about how casually it seems like he was handed a few dozen animators who just happened to have some spare time.

These scales (of both tech and personel) are staggering since the majority of the work I have done in the industry has been limited to what can be accomplished in a few months by a handful of people, but I am very excited (although terrified) to hopefully be a part of these sorts of massive projects in the future.

I also greatly appreciate that the people who are involved in these projects still respect the work that us little guys do, as demonstrated by a number of the Pixar engineers when I discussed my work on The Borgias with them.

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SIGGRAPH 2012 - Day 3

Technical Papers - Video Processing

Today I will focus solely on the video processing session. First, the eulerian video magnification really demonstrated a fundamental gap in my knowledge of signal processing. I like to operate by having an intuition of how every part of a system will behave once we start introducing changes or stresses, and working in the frequency domain is one of those places that still seems like magic to me (and in this case magic is a bad thing).

The paper on selectively deanimating video (see their webpage) resulted in incredibly cool cinemagraphs with very little user effort. While there are still a number of subtle artifacts that I would still remove if doing this work by hand, going from several hours of expert compositing to under a minute of untrained user interaction is a fantastic reduction of complexity. I am certainly inspired to break out some footage I shot a few weeks ago for this very purpose and give it another try.

Finally, the paper on seamless cuts of interview footage (see their video) was very conflicting. The technique is very smart and has absolutely stunning results, but the honest filmmaker in me (not just the general filmmaker, mind you) is absolutely appalled that this tool exists. Unless this becomes accessible to the general public (which it is not in the current incarnation) and therefore always in consideration when watching edited interviews, it exists to convince an audience that a third party interviewee is speaking within a context that is completely artificial. You don't have to take someone out of context anymore in order to twist their words, you can do it right in front of the viewers face without blinking.

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SIGGRAPH 2012 - Day 2

The day started with a little bit of a jolt, since sleepy Mike is apparently unable to operate an alarm clock effectively after watching the Curiosity landing. Once I finally made it to the conference, my first stop was the Pixmondo Hugo production session.

Sneaking in Hand-Painted Frames

My new eye for pipeline was very impressed by the massive amount of data that they automatically collected and shuffled around their numerous facilities. I can only hope that when I finish breaking and rebuilding the data flow at work that it can be even remotely as smooth and impressive.

There was a lot of focus on the miniatures used for the train crash sequence. While many people may question how you could get away with miniatures in stereo since your brain can figure out scales from the stereo imagery, they don't realize that you can simply shrink the scale of the camera system (by scaling the interoccular distance by the same as the model scale). This not only gives you a feeling of the intended scale, but I would believe that the cues picked up by the brain are so powerful that they would likely override other details and let you get away with miniatures even easier than before!

Another interesting challenge in stereo is how to deal with some of the often forgetten details of the medium:

Stereo can turn the most mundane aspects of filmmaking into the most troubling; improperly displaced grain will melt your brain. #siggraph

@mikeboers on . Visit on Twitter.

If you have random grain on both eyes then some fraction of them will line up and be perceived as physical bumps. If you have the same grain on both eyes (potentially offset by a constant amount) then you will perceive a fuzzy veil hanging in the frame. What Pixmondo ended up doing for the heavily stylized segments that called for turn-of-the-century grain is generating one set of grain and displacing it by the disparity map for the second eye, effectively wrapping a layer of grain around all of the objects so it ends up on their surfaces.

Finally, I was delighted to learn that there is at least one shot in the film in which the color was hand painted as an homage to Méliès' films themselves. While it was done in Photoshop, they still made the painter work on a 35mm sized frame. Paraphrased:

You really made some poor bastard paint on that tiny frame?!

Mike Seymour, fxguide

Open Source Can Not Be Cancelled

A few minutes into the time slot for one of the "birds of a feather" sessions, someone from the conference announced that the session had been cancelled for unknown (to them) reasons. The immediate reaction from a fellow named Benjamin (who works at a place called Rushes in the UK) was "How about we just keep talking anyways?". I was delighted at what followed:

The open source pipeline framework #bof at #siggraph was cancelled, but went on anyways due to the enterprising attendants, and a brave MC.

@mikeboers on . Visit on Twitter.

He went on to direct an impromptu discussion with most people electing to stay. I think I have a better handle on answering fundamental questions such as "What is asset management?" and "What is a pipeline?", although those are topics for another time. We ended up with a large mailing list with subgroups for local chapters to carry on the conversation later this year.

CrossShade

I made sure to catch part of the sketching session including CrossShade, for whom I designed and implemented the non-photoreal rendering pipeline for their results. They certainly took what I had created for them and ran with it, creating some really nice looking results.

Someone in the audience asked about integrating the normals (into a depth map), which is something that the researchers and myself both tried to implement (although they were most successful with it than I was). I really wish that we had been able to finish that as the lighting clues from proximate geometry would have been a subtle but fantastic inclusion.

Sake and Desserts

I attended the traditional opening of the sake barrel, in which Paul Debevec enthusiastically landed a quick follow up (and final) blow with his wooden mallet after the carefully choreographed countdown to the first (and synchronized) blow. Shortly after came the annual dessert reception.

I had a number of fun conversations including ambushing the emissaries of Dropbox to quiz them on their upcoming two-factor authentication (which I have confirmation is using OATH, which will work nicely alongside my existing systems). Good for Dropbox for (apparently) sending them just for interest's sake. I also met up with former colleagues and will potentially be getting involved in more graphic research consultation work on the side.

Lots of exciting things are developing!

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