chris cunnington

I recently needed to process all .png and .tga files in an entire folder structure including sub folders. The process was pretty simple and using python via the PIL module (for .pngs) and Image Magick (for .tga) I simply took any images found and made half resolution and quarter resolution versions (effectively MipMaps, but not stored in a single image). Problem is that we are still generating textures for other scenes/shots and so I decided to automate this ‘mipmap’ task via photoshop scripts for the texture artists. So after a mini crash course in JavaScript & reading the Photoshop CS3 Scripting Guide this is what I came up with. Honestly, probably not the cleanest code… but it does the job and that’s what counts when you’re mid production.

The Scipt

this version saves out 32bit TGA files with their alpha channels

//set up
preferences.rulerUnits = Units.PERCENT
displayDialogs = DialogModes.NO

//Doc Info
var docRef = app.documents[0]
var typeLayer = app.activeDocument.artLayers.add();
typeLayer.name = app.activeDocument.name.slice(0,-4);

// Save as a new TGA file with these options.
var Options = new TargaSaveOptions();
Options.alphaChannels = true;
Options.resolution = TargaBitsPerPixels.THIRTYTWO;
Options.rleCompression = false;

//make HalfRes
var resize = docRef.resizeImage( 50,50 )
var saveFile = new File(decodeURI(activeDocument.fullName.fsName).slice(0,-4) + "_med.tga");
app.activeDocument.saveAs (saveFile, Options, false, Extension.LOWERCASE);

//make QuaterRes
var resize = docRef.resizeImage( 50,50 )
var saveFile = new File(decodeURI(activeDocument.fullName.fsName).slice(0,-4) + "_low.tga");
app.activeDocument.saveAs (saveFile, Options, false, Extension.LOWERCASE);

//close without saving
app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);

a modified version by simply changing the save options & file extensions allows you to just about any format, we also use the PNG format so therefore

// Save as a new PNG file with these options.
var options = new PNGSaveOptions();

is switched out to save PNGs.

// Save as a new TIF file with these options.
var Options = new TiffSaveOptions();
Options.alphaChannels = true;

is switched out to save TIFs.

Download Scripts

I have put them both into a Zip File with instructions on how to install and use, and that is Downloadable Here!!

Enjoy!!

~C

Its been sometime coming, since I have been experimenting and planning this for sometime now, but its finally nicely on its way. The whole concept was born from the desire to create my own DCP Packages for testing of stereo footage at our local Digital Cinema. It is effectively a Gui based front end to quite a few command line tools available online for the creation of DCP files.

This first phase automates the entire process of converting an image sequence to the cinema jpeg 2000 format. It can handle 2K stereoscopic and 2K monoscopic flat formats (not scope yet) and exports the image sequence ready for DCP Packaging. Currently the conversion from sRGB .tif takes roughly 1min 30secs for 24 stereo frames (effectively 1sec of film). When stereoscopic is enabled it converts each image stream independently considerably speeding up the conversion time. Originally these conversions took nearly 6mins per 24frames when run as a single process.

As it stands the converter takes care of a few XYZ colour space conversions, outputting a 12bit XYZ Image following the Cinema 2K specifications. I am quite interested in colour space so hope to expand this area in the future.

Roadmap

The roadmap for the next phase includes, Implementation of 4K Cinema standards under monoscopic conversion, MXF Wrapping for both Video & Audio, and the creation of the DCP Package xml files. Ultimately I hope it to be a full DCP conversion and packaging tool!

I am interested to know what other options may be needed, what colour space’s do most people work in, would the loading of a custom LUT be of value, should I investigate input formats such as DPX and EXR?

~C

We have finally released a Stereoscopic Promo/Trailer for Zambezia the upcoming animated 3D movie from Triggerfish Animation Studios. Zambezia is the story of a high-spirited young falcon determined to be independent of his stifling father who leaves his remote home for Zambezia, the famed city of birds, and discovers that the greatest thing he can fight for is community.

To watch the 3D version you will need to visit Youtube by clicking here -> S3D Promo Trailer make sure to check it out or download it and watch it in Stereoscopic Player!

2D Promo Trailer

A discussion regarding Softimage 2011.5 some weeks ago prompted me to write this post. I inquired as to why Softimage has standardised to only offer side-by-side stereo pairs (be it cross or parallel) instead of the Over-Under format, their answer was simple,

‘To be honest we spoke to a few customers about their stereo requirements and you are the first (that I am aware of) to mention over-under for stereo previews. Could you maybe explain the advantages of over-under for you guys and why you settled on that standard?’

Now I truly feel that the over-under method for storing stereo paired video footage makes far more sense than side-by-side… and here are my reasons.

Often with stereography you require HIT (Horizontal Image Translation) in post, effectively sliding your images left or right to move the depth bracket back and forth in Z Space. Now with images stored in a side-by-side format at 1920×1080, each eye is halved (960×1080) on the horizontal resolution this to start with is a bad as our eyes are separated horizontally so any loss in pixel resolution on the horizontal has the most direct effect to viewing quality when re sampling these images back to 1920×1080.

Secondly and referring to the HIT if you slide your left image right & right image left your pixels are crushed down the center and lost because the stereo re-sampling method always cuts at the halfway mark of your image resolution. Over-Under avoids both of these issues by maintaining full Horizontal Pixel Resolution at 1920×540, and also avoids destructive behavior to the resolution of the image because the HIT happens down the Horizontal not the Vertical. (sounding very outer limits there, lol)

The introduction of black pixels down the edges of the frame occur in both side-by-side and over-under formats, however they are overcome by the over rendering of frames. We render a buffer of 20px on either side allowing for an overall HIT of 40px left & right. The most important fact to note here is the destructive tendencies of side-by-side footage when images are HIT inwards, and the fact that most editing software assumes that anything beyond one side of the halfway mark on the horizontal is the opposite eye therefore even with the over rendering of pixels, black bars centrally are unavoidable.

Thirdly, many of the new passive monitoring systems such as the Zalman Trimon 3D Display and the JVC GD-463D10 use a horizontal interleaving polarization method. This effectively makes every alternate row of pixels polarized for a specific eye. When converting a side-by-side stereo pair to be viewed on a interleaved monitor you loose a quarter of your total video resolution. The side-by-side video is halved on the horizontal (1 half lost) and then when the monitors interlace the footage each alternate row of pixels is lost due to it being used to show the opposite eye (1 half lost) this effectively means you only see a quarter of your total resolution.

The Over-Under format stores the images with full horizontal resolution and has the pre-compensated for the loss of pixel resolution that occurs during the interleaving process. Therefore there is no loss of pixels. We use Stereoscopic Player to preview the captures in stereo weather it be on our Polarised Horizontally Interleaved Monitors or Active Projector (Quad Buffered) as it deals with converting the input formats to the required output methods. The same applies in our edit suit where we monitor stereoscopic on a Panasonic TH-P50VT20P

Just on a final note, the HDMI 1.4 stereoscopic standard is two full resolution frames Over-Under…

~C

Quiet a bit has been happening in the media regarding Zambezia, here are a few of the articles and other odds and ends that have been going on at Triggerfish

A recent article in Screen Africa Magazine regarding Zambezia and Stereoscopic

Recently animationmagazine.net also wrote a great article on Zambezia and Triggerfish Animation

“We are opening the window into a world not many children have seen – the mighty Zambezi River Valley, the awesome Victoria Falls and the varied and rich cultures (and birdlife) of Africa,” says director Wayne Thornley.

We also received some exciting news regarding Khumba, Triggerfish Animation Studios second animated feature film. The Industrial Development Corporation (IDC) approved the much needed funding. This means that as from 1st October we are officially in production and it’s all systems go!

Its been quite sometime since my last blog post of any major substance. Its been a pretty amazing few months since moving to Triggerfish Animation Studios heading up the Stereoscopy Department. Doors have been opened allowing me to explore areas of 3D & Computing Technology that I have always longed to explore yet never had the time or need for. Integrating Stereo 3D into an Animated Feature Film comes with its inherent challenges and requirements. I work closely with the Animators, Lighting & Compositing Departments continually working towards a comfortable & enjoyable 3D experience. The mathematics of stereography has also been an exciting challenge, nothing like a little trigonometry to keep your brain firing on all cylinders.

Simple intro to the Mechanics & Mathematics of Stereoscopy

Stereoscopy at its simplest form is straight forward, we create two image sequences one catering specifically to your Left Eye & one catering specifically to your Right Eye. Those images are created in such a way that they attempt to recreate the best possible S3D effect for all who watch the film. Basically our work mostly concerns the z-axis (objects in front or behind the screen), behind screen is known as the Positive Parallax and in front of screen is known as the Negative Parallax.

But why does the area coming towards you get called negative and the area moving away from you get called positive? Well that’s where the above scene geometry comes into play. We all work on screens, weather its your computer screen or the cinema screen, and that screen we call the Zero Parallax, its the one point where what both your Left & Right eyes are seeing is perfectly matched. Now if we attached red lasers to each of your eye balls (very terminator style) and asked you to look behind your screen and then measured the distance between the two red dots (at screen position) we would find a positive number, but if we did the same with you looking at an object in front of the screen the Left dot would cross over the Right dot and thus, remaining in the same mathematical space, the new measured distance turns up negative.

Now speaking of the positive parallax, where your eyes are looking parallel to one another, and you are looking at a distant object. Although comfortable and natural, most of the time your eyes spend their days converging on objects, but if you attempt to diverge (make your eyes move apart, as seen above) the eyes to much, this is what I consider the primary physical danger zone of S3D, no one likes having their eyes forced apart.

This is where the mathematics come into play, we need to know the maximum positive parallax the human eyes can handle at the screen size of your final deployment screen. Its a simple ratio, if the human eyes average distance apart is 65mm (Interocular) then you need to know what percentage 65mm would be on your specific screen. Lets take two examples, firstly a 500mm computer monitor, and secondly a 9meter cinema screen.

Percentage of Screen = (Interocular / Screen Width)

0.13% = (65mm / 500mm) or 13%
0.0072% = (65mm / 9000mm) or 0.72%

Now if your Screen Resolution is say HD (1920×1080) you can work out the how many pixels would make your eyes sit in parallel in the resolution you are working.

Pixel Parallax = Resolution x Percentage of Screen

249px = 1920 x 0.13
14px = 1920 x 0.0072

So effectively what this says is that at a screen size of 9m wide, the maximum pixel separation you should go to is +14px when showing HD Footage. The next area of concern is distance towards the viewer in the negative parallax, but in my opinion this area is a little more flexible. Obviously extremes are just as dangerous as extremes in the positive, but the pixel values in the negative can be quite a bit larger without putting to make strain on the viewer. I plan to write a post specifically about the negative parallax because it alone is a large topic of discussion in its own right.

This being the simple intro I will stop right here, but it does get quite a bit more complicated when you begin to take into account the physical location of the viewer relative to the screen on the z-axis, etc

C

The Callsheet recently wrote an article on Stereoscopic 3D in South African film, prompted by a visit to SA from Jessica Abroms, a former technical director at Pixar. A few companies were mentioned including Triggerfish Animation Studios since we are currently working on Zambezia, our first Stereoscopic Release. Below is a scan of the Article

Click for Larger Version

Its been a while since my last proper Gaming, Animation or 3D related post… its been tough working under pretty strict NDAs. I have however been very busy developing, growing and writing tools for our in-house pipelines and furthering the stereoscopic pipeline.

C