Front Projection Mapping...
 

Here's my front door...  Wanna come in? Yep, then click here (DivX)

Ok, so its been used for ages for cool compositing effects on still backgrounds, right?  You'd draw a silhoette of a building or tree, then fly that cow behind it...  Very cool indeed. The problem was, move the projection-mapped objects, or camera, and the mapping goes out the window - The images stays in the same place, att the same size even if you wanted to fly forward or backward.  To do anything serious, you'd need to start looking at those photo-modeling tools like Canoma, or get RealViz right? No Way!  With the release of Lightwave[6.5] comes Fixed front projection mapping!  No more dreaming of buying a hi-end package to map those photo's to models - Its here right now, and in everyones favorite 3D animation package too! (Gosh!) Download the AVI file (222kb) and see it in action for yourself!   (Note that you'll need the DivX codec to play this file.  You can download it here for multiple platforms.)

The Process...
This is not so much a tutorial, but more a talk-through of how I used fixed projection mapping to recreate my own front door in LightWave using just a photo, some inspiration from a book and 10 spare minutes!

In this case, I'm using a low-res snapshot of my own front door taken with my Sony Handycam.  If you are just trying this technique for the first time, then I would suggest picking a photo of something simple (ie. cubic shaped like a office block, or a doorway like this one, or perhaps even a table!)

If you want to have a go at my doorway, just save the image above (its low quality at 320x240, but its good enough to play with for now) 
 

Step 1: With my photo in hand, I started by first modeling an approximate mock-up of my front door area as seen in the photo in modeler. Ideally, I could have measured the area and modelled it accurately, but for this tutorial I wasn't too fussed.. In the case of doing this for a paying project, you would probably want to be a bit more accurate, not to mention ensure a high quality photograph. Once the front door was modelled to approximately match the photograph, the object was saved and it was off to layout to perform our magic.

In camera view, align the model to match the photo

Step 2: I started Layout and loaded the photo image, as well as the model I had just built. Select Scene/Compositing and set the background image as the photo.  I also pressed d (display options) and set the camera background to be the background image.  This got my photo on screen as a reference. With some muddling about of the camera, and a bit of tweaking of the model I managed to align the model to approximately fit the photo image itself in the background.  It wasn't perfect, but it was close. I then keyframed the camera (and the model since I'd moved it) at frame 0.  I then pressed d and selected Blank as my camera background (to speed things up a bit).  I also removed the image from the compositing setting as I didn't want it rendered in the background!

Step 3: The next step is simple - To set the surface map.  Select the surface editor,  set Diffuse to 0% and luminous to 100%.  You can leave all the other settings as-is. Click the T next to the color setting to bring up the texture editor. Select Projection as Front, and tick Fixed Projection.  Time should be 0 (since the camera and model are aligned at frame 0) and reference camera should be set to the camera (in case you have multiple cameras) That's it.  You're done - just like that!

I then moved the camera in towards the door and the results were better then I imagined!  Of course, its not perfect, and I suggest you carefully plan your animations when doing this since some angles really don't work! (Trust me - I put a couple of them below as proof!)

Snapshots from the Video:

The camera is moving into the photo!

It looks nice at different angles too!

Here's some BAD angles!

Don't look up! Seems that theres a bit of distortion going on!

Doh, half the door is missing (and the wall is there!)

Some tips:

• Use high res photos for more detail.  If you can, measure up the item before you model it so that you get things as accurate as possible.
• Try and calculate the same camera settings as you used when taking the photo - This will help align things more accurately.  Otherwise, doing it by hand is just as much fun! ;-)
• Remember that the mapping is calculated at a specific time, using a specific Reference Camera.  A good idea would be to parent the camera you are using to map the image to the object to the object itself, then create a new camera for any animation work instead.
• Don't move the object unless the Reference camera is parented to it.  You'll screw up the image mapping (try and see (but save the scene first!))
• Did you know that you can BAKE the Fixed projection map onto a UV surface too?! Just be sure to select 'Bake Shaders' in the LW_BAKER settings. :)

Many thanks to Dan Ablan for introducing me to this feature in the LightWave[6.5] magic book.  Incredibly, I never realised it was there... This just goes to show that reading the manual really would be a good idea, huh!  ;-)

Cheers!
 

Kevin 'kevman' Phillips
This page/article Copyright © 2001 Kevin Phillips