tridimensional projection mapping.., a lot faster for rendering?

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Old 10 October 2012   #1
tridimensional projection mapping.., a lot faster for rendering?


I was just checking a great tutorial the other day by Scott Metzger on youtube part 1, part 2, part 3, about painting with HDR images photos on 3d objects and use that to have a complete environment with objects that are close to the camera with all the light and shadows bake in.

I have never try this projection technique before, but in the video looks great and very very fast. Would this be a good technique for render very fast environments with objects that are close to the camera, etc with good quality..., or render times would be similar with environment with all the textures, shadows, lighting with no projections?


Last edited by yolao : 10 October 2012 at 08:31 PM.
Old 10 October 2012   #2
Projections can be a great time saver, and render very fast compared to full-blown global illumination stuff. Keep in mind that you won't get any reflections, refractions or interactive light this way.
This should take less than a few minutes.
Old 10 October 2012   #3
thanks Niko.

Last edited by yolao : 10 October 2012 at 12:07 AM.
Old 10 October 2012   #4
Projection mapping is a rather common 2.5D and 3D matte and environment technique.

It works great to a point, but most materials have reflective properties that will at some point be camera angle dependent (specularity being one of the most common, pure reflections and refractions being another and a lot harder to cheat back in than just specular reflections), so you tend to have to enrich those renders with some additional passes to bring those things to life, and then of course cheat the energy interaction of eventual moving objects on top of it.
It does give you a very solid first pass in many situations though, and in some situations it can get 99% of the way there.

I've done some stilling shots (making a city appear inhabited and destroyed) purely through multiframe photogrammetry in the past (projecting different frames of a sequence to build a panning texture for stand-in objects) and got away with it, but some life we had to restore back in in comp (luma keying some hot spots and reflections from the original footage and projecting that extraction as an additional pass).

The dead-London helicam shots in 28weeks later were all multiframe photogrammetry and done in just a few days for the whole sequence with just me and a comp artist on it.
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Old 10 October 2012   #5
great info, thanks. Yes. tweak some material properties in post would have to be necessary in many situations.
Old 09 September 2013   #6
Just bumping out this thread to ask about baked textures. It seems to be a nice option as well, adding things like spec/reflections later.

-What do you guys think, is it possible to bake out big scenes with thousands of polys and textures or is it just for smaller stuff?..

-If you render out spec/reflection later and also moving geo later, (like characters) what disadvantage could it have for static light background in an animation?....

I found this video on internet of a baked scene in vray and then take it out to Unity for realtime viz with reflections.

Old 09 September 2013   #7
The workflow mentioned requires HDRis and Lidars and used in Mari. The scans are millions of points, so will get re-modeled to a lighter mesh. Because its projected, you can get away with game resolutions.

Keep in mind, with this method you cannot relight the scene and can only work with HDRi workflows so although photoreal your flexibility is limited to working with baked lighting.
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Old 09 September 2013   #8
Thanks Mason. Yes, when dealing with dynamic lighting a frame by frame render would be required.

But with static lighting this technique (Projection M. or Baked T.) could be??? a good alternative if you don`t have the hardware to render out several minutes of animation at one hour a frame for example....

Last edited by yolao : 09 September 2013 at 12:10 AM.
Old 09 September 2013   #9
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