Front projection - Maya, Nuke and free scripts

I'm again back teaching Nuke to students.  Nuke 8 has some great features - in particular, I'm now officially a big fan of the colour wheels and scopes for working with grading...  But enough about that...
Thanks to one of my students last year, I became aware of a great free Python script called Maya2Nuke.  It lets you set up your scene in Maya and then export it, along with animation information across to Nuke.  And it does it extremely well I might add, but not without a little massaging to get there...



I figured a general overview of what this is all about wouldn't hurt here.  Some of you may recognise the character above as being the police officer that stops a young James Kirk in the first JJ Abrams Star Trek movie.  Note that he didn't originally have a flare in his eye, but more about that later.  Its a frame that I sourced from here to use as a personal learning project.  No copyright breach intended (it was used for educational purposes)

Whats up, doc?

I'm running Maya 2014.  I follow the instructions for the script which says to place it in the user's Maya scripts folder.  It then says to import it into Maya from the command line...  But it just comes up and can't see anything in Maya.  Secondly, it also generates an error trying to retrieve frame numbers.  In Maya 2014, these are returned as floats (allowing for fractional frames).  The original script tries to treat these as integers, so a small tweak is needed to make the code work.

Open up the Python script in a script editor (Maya, Notepad++, etc).  Scroll down a few lines (line 29-ish), and there you'll see two lines retrieving start and end frames for the scene into two variables 'min' and 'max'.  Its a very simple fix - just typecast these to be integers.

Secondly, once the script is loaded into the script editor, it can just be run from here and performs as you'd expect.  However, saving it to the shelf in Maya will just save all that hassle.  Its now ready to go.

Front Projection - the what, why and how

Front projection mapping is all about creating the illusion of creating 3D motion from a flat 2D image.  It does this by projecting the image as seen through the camera onto the geometry in front of it.  Usually you can fake the illusion without front projection through a 2.5D approach using cards or planes with 'slices' of our scenery applied and placed different distances from our camera...

But while this may work just fine for distant elements (and it is quite common for cityscapes, etc), for closer details, the fact we are using cards starts to break the illusion as we notice the lack of perspective when moving in or around the scene.  Things just look like, well, flat images on cards.

To give our artwork real "depth", we can project the image onto very rough 3D geometry that represents the form of the artwork itself.  For example, rock formations with insets and outcrops and buildings that are close by...

Rough you say?

The idea of front projection is to make an image appear to have perspective.  This means we're really more concerned with an image appearing to change, and not worried about lighting and rendering artefacts common from rendering low-poly models.  For the Star Trek project, I went for a collection of primitive shapes with a little modification here and there.

However, for say a shot of a sky scraper in downtown Los Angeles, simple boxes and a few small extrudes are all that's needed.  Here's a very simple example of one that I did earlier as a test.

K.I.S.S - basic geo just gives our image some depth

We can get away with fairly low detailed geometry - though high detail may be used in circumstances where intricate details need to have some geometric form.

How do we do it

The approach I use is to simply load up the plate as a background plane in Maya's perspective viewport.  Before I proceed, I'll make sure that this fits properly (I've been caught before by not doing this step).

1. Change the render size to the same dimensions as the picture.
2. Make sure we've set the viewport to display the resolution gate (its the small blue ball icon in the VP's status bar).  You may need to adjust the Camera attributes - Fit Resolution Gate to a vertical or horizontal option if you can't see the whole image in the viewport.
3. Open up the image plane attributes, and make sure that you click the Fit to camera resolution gate option to fit it properly.
4. If you don't, you can end up with the image plane not filling the background and the alignment of your scene won't work correctly.

I adjust the camera so that the grid loosely (you don't need to be perfect here - though it can make life a little easier) looks about right and then break up the image into elements that represent the main forms I will see potentially changing with any camera movement.

Model and place the basic forms in the viewport to match the picture.  For shapes like faces, or rocky cliffs, you can generate a simple plane or box with multiple faces, and push/pull them to create the basic form as seen from the camera.  For the background sky, I'll often generate a very large sphere and cut away the faces to leave a slightly curved background object.

Make sure that you approximate the distances from the camera that the elements sit, align/resize/etc until they look right and you're set.  Don't worry if some of the geometry spills outside the camera's resolution gate.

If you want to see your front projection directly in Maya, you just have to wire in the surface colour using a Utility node (rather then a file node).  The Utility node is called, oddly enough, Projection.  Setting its Proj type to Perspective, adding an image and setting the camera options (Our camera with Resolution Gate being the setting) we can see the result as per the render above.

While you don't need to surface the objects at all for Nuke, there are times where you may want to render directly from Maya rather then go the whole compositing path...

Prepping up the images

Once I have the objects in place and everything looking clean and aligned, I'll break up the original image into multiple layers and paint out details as the elements go backwards...  The reason here is simply to make sure if the camera movement starts to reveal what is behind things, we don't want to see that the same picture of the items appear on the background elements...

Below is a quick example - I painted into the edges of the house on a layer I was using as a background plate.  This meant that the foreground building geometry didn't get any doubled-image issues.  Of course, you could also just do a complete sky replace with a separate BG image as well if you wanted to.

Ready to roll...

At this stage, we're ready to just export the scene to Nuke.

Run the Maya2Nuke script explained at the start of this article.
Select the items you want to export from the list.  If you can't see all items in your scene, look in the Type menu and click the All checkbox.
The Animation menu lets you also process and export animated items.
Under Edit, click the Calculate Maya data - it'll process animated frames, etc.
Then at the very bottom of the window, click the big Generator button.

If it worked out, you'll get a message saying so!

Putting it in NukeX

Just open up Nuke,  then click in the Node Graph and paste.  The project's nodes should appear, ready to be used.  The overall structure is very simple...  Our 3D objects (exported by Maya2Nuke as OBJ files) connected into a scene, and then that connected to a scanline render set to use the camera we exported from Maya.  A simple example below shows the basic structure of that sky scraper scene.

Simple 3D node set up - just add textures and cook.

You'll spot that the nodes are named to match the items in the Maya scene.  Unlike my quick examples, you should ideally make sure to give all of your items proper names that make sense.  To be honest, this should be a general practise so you can manage your projects efficiently in any CG application.

Something else to be VERY aware of is that if you use objects without renaming them for a project, OBJ's generated from Maya2Nuke will just overwrite any existing files.  I ran into this headache when a fairly complex example I'd created suddenly broke badly.  Lucky I just re-exported the Maya scene to overwrite the overwritten files again.

The only thing left to do in Nuke is add a few read nodes to get our images, attach these to Project3D nodes driven by the camera node.  And then attach them into the objects.  To animate your shot, you will need to get a second camera node - do not animate the one from Maya directly as this one is used to project the imagery onto the 3D geometry itself.

Oooh!  Look - a lens flare!

To this scene I separated the background and character into two scanline renders.  The reason for this was so I could grade and manipulate these two elements separately if I wished.  I also threw in an anamorphic flare streak I rendered from LightWave3D to add some animated detail to the eye of the character.  Here is a full image of the finished Node graph.  I've splattered a good collection of notes through it to hopefully explain what does what...

Notes, notes and more notes...

I didn't really have much of a story behind this scene (it was a mere exercise as a way to test Maya2Nuke, and to prep up for class with an interesting example of front projection), so there's nothing overly exciting going on other then the eye and a slow camera pan (which shows off the perspective effect nicely)

So there you have it - a fairly long-winded explanation and overview of front projection mapping between Maya and Nuke.  Its a load of fun, and lets you quickly create moving backdrops and elements from matte paintings, photo's and images.

Its well worth learning to do - front projection is something that's used throughout many a visual effects shot...  Hope that this article has been of interest to someone out there on the Interweb...

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TECH : Broken doesn't mean it can't be pretty...

Recently a local retro collector was giving away some of his excess gear - in his collection, he had an old Commodore 64 that was dead. It had been gutted - all of its chips had been removed and someone had soldered in a few random wires - and it was missing a few keys which had broken off.  While only my brother had Commodore (I was the "Sinclair" side of the family), the old "bread box" styling of the machine is iconic.  I also felt even if it didn't work, it could make for a nice display unit.

Not one - but two - but inside none...

On a little googling, I also saw a few small projects with Raspberry Pi emulators, old keyboards and a device called a Keyrah.  It is a small PCB that converts the Commodore keyboard input into a USB compliant USB keyboard.  I figure if I get the time, I may consider looking into projects like this at a later date.

Inspection - yup, its missing a few keys.

The machines arrived well packed inside an old Banana box.  I'd been sent two (I only expected one) - the Commodore 64, and a Commodore 64c that apparently would only produce a black screen and was rather messy inside as well.  The Commodore 64c's keyboard, however was intact.

Yes - I suspect that there may be something missing here

I'm not a big fan of the newer model casing that Commodore started to release its machines in (the later C128, Amiga 500's, etc).  While I could have just transplanted the keyboard across to the older box, its keys are light and the old bread box has great looking dark brown keys.  To keep the retro appeal, I just needed to replace those 3 that were missing with brown keys.

Washing away the dust

These machines have obviously been stored somewhere dusty - covered in grime and dust bunnies (or as they are otherwise known - clumped dust and hair) - a quick wash in some warm soapy water did wonders for the cases.  Obviously - I removed the keyboards and PCB's first!

So it was off to eBay...

I found a reseller who had classic brown C64 keys (refurbished, but in very good condition).  He also had pegs (the things that had snapped on the old keyboard, hence the missing keys) as well as springs.  So I ordered the 3 keys I was missing, a pack of springs and stems.

3 missing keys - now found (on eBay).  US$3.99 each

They arrived around a week later.  So - a little unscrewing (the keyboard PCB has almost 16-20 tiny screws hold it on) and some prying later, I managed to get the pegs in place, sit the springs on top and clip down the keys.

So many screws!

Viole!  Now looks much nicer.

Ta-da!  Now almost complete...

But something was still missing...

The C64 was missing its power LED.  This is a cheap 5mm Red LED - around $0.25 NZ cents.  I bought a couple (along with a green and a yellow one - Just because I could round it up to $1.00 - and because I thought its always handy to have some on hand)

At first I thought I would just clip it into the small black mount - it fits great - but then the clip is way too wide to go back into the case.

I placed the clip back in, inserted the LED and carefully (but forcefully) pushed it in with a pair or needle-nosed pliers.  The "click" meant it was in, and the case now looks complete.

Still one last detail... But for now...

There is still a missing black plastic cover that sits over the joystick and power connectors on the side, but from what I can tell this is really just a piece of black plastic with holes carefully punched into it.  Something for another time...

Something for another rainy day

Ready for display... or...

The case looks great (as long as I don't stare at the joystick connector "space" in the side) - its a classic design, and along with the ZX Spectrums (all 6 of them - lol!), the Atari 600 and the C64c - I now feel I need a display space.

I am definitely keen to make these two C64's at least do something more then sit pretty.  At a later date, I'll try my hand at throwing in a Keyrah interface.  If I'm feeling ambitious enough, a Raspberry Pi project may also be on the horizon...

UPDATE (April 2014)

Thanks to Terry 'tezza' Stewart, I now have that elusive plate.  It was definitely a lot different then I had imagined it to be (wasn't quite as simple as a 'plastic with holes')... A metal plate, with a large base folded flat to sit underneath the Circuit board.  However, that aside - I can now officially say that the case is complete...

Woohoo!  Nuff said...

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Inspiration : Art books from three favorite productions

Figurines are a great inspiration (as I've said back on this blog entry), but something that is even more inspiring for me is the many art books I have here. Looking at concept art, model sheets and reading those stories that remind me why I love CG - its what keeps me driven and passionate.

In the last couple of months, I've gotten 3 - Pacific Rim : Mans, Machines and Monsters , Elysium : the art of the film and just recently Transformers : the art of Prime.

I felt a quick personal review would be a nice entry for the blog, and for those interested in these books. I like all three, but for those who were thinking about it - here's my personal take on each...

Pacific Rim : Man, Machine and Monsters

This is a nice book - its fairly large, and what's great is that it comes with a dust cover. Its an interesting browse. Inside is a little odd in that there are a lot of small pieces of artwork on removeable sheets spread across the pages.

Small removable sheets (like the one on the left) are spread throughout

I'm not sure if I should remove these (they are attached with easy-to-remove gum) or leave them. They sit over page artwork, and while I'm tempted to take them out - I'm also not sure where they would be stored (ie. to keep them with the book).

Great artwork, but those removable sheets (that blueprint) can get in the way.

Visual Effects and Special effects have various storyboards. But could do with more imho.

As expected, plenty of detail sketches and coloured artwork

Overall, this book is well written, and its got plenty of artwork and concept material. To be honest, as much as I like this book, I do feel it could do with more art and design sketches. Many of the photo's and imagery I've seen on the special features of the Bluray, or online.

However, its still a good look at the movie itself along with its production and design work.  I loved this movie, just for watching all that cool ass-kicking visual eye candy - its not a film I'd watch if I was after a meaningful and complex story however... lol!

Art of Elysium

This is a fairly wide book. Its a little awkward to browse through when sitting on my lap, but its a book that's well worth the cost if you're into the grungy design that Weta and Neill Blompkamp have bought to the cinema screen.

This book is very reminiscent of the District 9 art book I got a couple of years back at the Weta stand at a local NZ convention. Like that book, this one also features lots and lots of nice artwork, breaking the production right down to the small details such as the tattoo designs that the characters wore.

Right down to tattoo's, costumes and more - the books got plenty of great info...

Overall, as I said, there's a lot of great material in here. A mix of written material, with a good dose of conceptual artwork and sketches, as well as photo's.

As you'd expect - weapons and ships feature throughout.

The many, many sketches and paintings really show the amount of design that went on.

I'm a fan of both of Neill's films. I love the style, the stories and the gritty nature of the films themselves - Seeing the artwork and reading about the process just increases my respect for the amount of work that went into these productions...  Great stuff...

Transformers : The art of Prime

I'm a big fan of this animated show - and the book as well - its loaded with detailed images of characters, set designs, matte paintings and all the eye candy any self-respecting fan just has to see.

The overall dimensions (12.6 x 9.6 x 0.7 inches) make it a nice size that sits on your lap nicely without being too large or too small. The book has a nice matte cover, with the title text (and images on the back) in glossy print. If anything could have been improved on, it would (for me at least) have been a nice dust cover to protect the book itself...

Another thing I noted was that the cover, and the matte black paper that sits just inside of it are prone to picking up grease so if you're going to browse, make sure to clean those hands beforehand (you could say this for any book mind you)

The book is broken up into 3 sections on Characters & Props, Environments and Color and effects. Inside each section are chapters that break up the types of characters (ie. Autobots, Decepticons and Humans), locations and various effects and paintings.

Great glossy coloured print throughout the book.

The book content is broken into parts, each with sub-chapters...

A variety of conceptual art and sketches, renders, and illustrations with small paragraphs and comments inserted where they relate to the artwork are spread through the 200 glossy printed pages.

A good mix of details - model sheets, notes and colour art work.

I was quite excited to see just how much material was in here. Not only model sheets and coloured artwork, but many characters had a breakdown of their transformation sequences amongst other small details such as props or conceptual designs.

Good breakdown's of smaller details such as the transformation sequences.

Plenty of model sheets and sketches everywhere.

Added throughout the book are full interviews - from 3 to 5 pages, the interviews go into more depth with the core team behind the development of the show. There's a lot of interesting snippets of info within these, and of course a little more artwork to break apart the text.

With this book being mostly a collection of great artwork, I have to say out of the three its one of my favorite books.  This is most likely influenced by the show being a completely CG animated one and the fact I'm a big fan...

All three are great reads.  If you need more material to inspire you, check them out.

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TECH : Dk'tronics keyboard labels - part 2

Back in my previous blog post, I explained the process and gave a link to a set of labels you can download and print for replacing worn labels on a dk'tronics keyboard for the ZX Spectrum...

I have tweaked this document with appropriate colours for the symbols and extended mode keywords.  I also made a version with grey backgrounds that may be of use to those who can't get transparent label sheets (or if you have a different extension keyboard that you need labels for).


The download links for these are here.  Enjoy!

Transparent (colour version)

Transparent (black version (original))

Colour (grey version)

Note to those who grabbed the keyboard labels from my previous blog post that I've slightly updated the file to add in the colour labels for the numeric keys.  You may (or may not) want to re-download the file (the links also updated in that previous post).

Now in 3 different flavors...

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TECH : Re-labeling a worn out Dk'Tronics...

As far as I am aware, DK'tronics released two versions of their products.  The first one had stick-on labels for the keys.  The second, of which I have, printed the labels directly onto the keys.  While the print is pretty resilient, sometimes those greasy fingers can just wear off the hardiest of inks.

So - with those keys being almost perfectly cleaned off, how was I going to "restore" this old device.  The answer was to look around and see if anybody had released new labels for these keyboards.  As far as I could tell, there was nothing to be found.

Late night greasy pizza, or just sweaty fingers (ooh!) can cause issues...

Well, if you can't find them, then you make your own.  With a little observation, and Adobe Illustrator, I've created a set of new labels that can be printed and used to replace any worn keys.

Printed onto transparent label paper, ready to cut-n-stick

I'm sharing these here for those of you who are in a similiar situation.  All I ask is that if you download this file, please do not redistribute the file online elsewhere without first asking, don't remove my name/blog address (or change it/modify the image/claim it as your own work) or use it to make a profit through selling printed labels from it.  Just a little respect for the work I put into this is appreciated.

You can download the labels here.

By printing this home-made set of labels to an A4 sheet of glossy adhesive transparent acetate paper (you should be able to find these at your local art supplies of stationery supply store), I managed to restore the few missing keys.  Ideally, all keys should be cleaned off and replaced, but for what I need right now, the few that were almost completely cleaned off was a great start.

Clean, align and stick - its as simple as that

I will be uploading a coloured version of this for those wanting non-transparent versions.  I'll post that up as a new blog entry in the next day or so.

Just a note - I printed these on a lazer printer.  If you're using an inkJet, consider sealing them somehow.  Either a transparent sealant spray (which doesn't damage plastic label paper, obviously) or by placing a clean transparent label over the top.

Ink tends to easily smear or wear.  Lazer prints are much more resilient to wear and tear from constant pressing...  Just be weary...

Enjoy!

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Tech : Fixing the Dk'Tronics keyboard for my ZX Spectrum

Yesterday I decided to take a ZX Spectrum I've recently repaired and place it into a larger keyboard that I'd had since the 80's...  The reason for using a different keyboard? I'd replaced some components on the PCB with modern counterparts that were actually a lot larger and this made things a little cramped when screwed back into the Spectrums original case.  It made sense to use my classic Dk'Tronics box that was designed as a replacement for the original rubber keyboard.

The reason I'd originally gotten this keyboard back in the day was because I'd upgraded what had been a lowly 16k ZX Spectrum to a full 48k of RAM. That meant opening the machine up, inserting RAM chips and putting it back together.  All went well, except the space key slowly started to fail - notably while playing a game of Manic Miner (which used the space key to jump).

A real keyboard vs. rubber "dead flesh"

Why fail?  Well, the way that the ZX Spectrum keyboard works is that it uses a thin membrane system that has two layers of metallic tracks.  These are separated by another very thin layer so they do not make contact.  A rubber keypad on top of these presses down on the membrane, and that causes the layers to make contact and hence "press" the key.

The membrane is thin, and it can be quite fragile.  So when this had stopped working, I had to find something to fix it. The Dk'Tronics keyboard was a "real" keyboard, and the connectors inside were much more reliable (being cables and not a membrane).

Anyway...

So, I swapped my Spectrum PCB across to this keyboard, plugged it in and booted up the machine.  All started up, then I pressed a key.  Great.  Worked...  I pressed another.  Hmmm...  Nothing...

I then proceeded to press key after key - nothing, apart from around 10 keys seemed to be working!  Argh!

Inspection time!

I opened the keyboard back up and checked.  Its old, but it didn't look too bad.  It has been stored in less-then-ideal damp locations, so I wondered if perhaps there has been some corrosion...  From an initial view nothing looked rusted, grimey or damaged.

I did however spot a handful of partially soldered pins - so minimal they appeared to not be soldered when viewed from above.  I also looked closely at all of the soldered joints and spotted a few cracked ones.  Awesome - those were relatively easy to fix with a hot soldering iron, some flux and a little fresh solder.

Soldering fixxer-uppers...

Soldered - then tested again.  Nope.  That didn't help at all...

Dampness - corrosion - hmmmm....

I continuity-tested the cables (with a multimeter) that ran from the connectors at the end of the cables through to the keyboard.  I traced along the tracks - not all of them - but I made sure to do a few.  Nothing appeared faulty.  Everything connected...  Hmmm...

So I quickly googled things - low and behold, I found this web page that talked about repairing this keyboard and commented that the contacts inside the buttons can get dirty.  Given the damp conditions of storage, this wasn't out of the question... So I tested one button that didn't work...

At first how to open these buttons seemed confusing. However, a simple thin plastic clip on each side of the button allowed the top to be popped off and the insides extracted for cleaning...  Using a very thin screwdriver blade, slip it under and gently push it outwards.

Two clips - one on each side.  Take care, they can snap easily.

I had to agree with the web site after I managed to snap one of the clips off - opening these up was tricky, and given how close the buttons were meant I couldn't get a screwdriver under the other side to pop the clip.  So I followed the advice and unsoldered one of the keys.  The age of this hardware did prove a problem - I did manage to lose a little of the pad when I sucked the solder - but luckily not too much of it to require a repair job.

The actual plastic key on the top popped off with a little prying (its just pressed down on a "+" shaped stem).  Opening the button revealed the following parts (see image below).  One of the contacts was in the middle of a grey rubber cup that is pressed down onto two contacts below to make the connection.

Pretty simple on the inside...

Now that I had this button removed and opened up, I grabbed a cotton bud with a little methylated spirits and proceeded to rub across both both the top and bottom contacts.  The lower contacts in particular had some corrosion, but the small copper contacts in the center looked a lot cleaner once swabbed...

One key had a dark spot that wouldn't rub off, but a gentle scrape with a screwdriver loosened whatever it was and removed it.

Clean both contact points with methylated spirits

I reassembled the key, re-soldered it back - plugged it back in - Fixed!  Awesome, but now I had the rest of the keyboard to deal with...  I desoldered 2 other keys, each time watching for damage to the pads on the PCB.  After testing all 2 were working, I knew what I had to do...  However - I wasn't looking forward to desoldering and clean the remaining 50 keys.

Specialised tools for the job

Instead of the unappealing approach of desoldering each and every key, I discovered a custom tool that was small enough to slip between the keys to hook under each side of the button and unclip it.  This tool you can buy from any stationery stockist - its called a paper clip!  Bent over to form a tiny hook, and by crimping the end as much as possible to get it thinned out - it shaved hours of soldering right there and worked a treat!

Specialised keyboard repair kit

I'm glad to say after a couple of hours work - the keyboard works perfectly yet again, and enough to load and play a few games...

 Now to check some RAM - a few crashes, a little testing and seems things aren't quite right yet.  But its close to done.  Great fun!

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