camera mapping tips

[pgill]

Hi all

i put this up on the autodesk support forum…maybe it’s of some interest…

some tips for camera mapping a clean painted plate (or matte painting)using the 3d camera tracker or boujou

you can use projectors to project the clean plate onto bicubics/geometry. the difference to just slapping in a layer is in the way you get the parallax correct for the clean up area rather than it just be a sqaure-on layer with a 3d camera move.

you just add an image with a black layer (simple add) to project onto and parent this to the closest tracking marker which flame gave you. then offset it to get it in correct 3d space

somethings i have learnt from using projectors for this purpose:

– copy the new tracking camera and delete all keyframes other than the one to match the paint up (eg. frame 1)

– make this cam parent to the projector. copy the fov from the camera to the projectors fov ( it doesnt inherit through the hierarchy). reset the z in the projector to zero (it defaults to 500). your projector should now match your background (its best checked on frame 1 in this case for initial match)

– it will always look good on the frame where you did the matte paint (frame1)(provided the track is good and you match the projector as described above) but when you scrub through the timeline you will see whether or not your scales/rotations of your bicubics are correct. If the cleaned up element moves more than the same area in the background plate when scrubbing timeline then it is too close to camera. If it does not move enough to keep up with itself in the backplate then it is too far back. You can use the other tracking markers for reference points to help.

OTHER POINTERS:

– choose your frame for clean up matte painting according to scale. i.e try and get it on the frame where the area to be painted is closest to camera. this avoids softening. If adveresly you use a frame furthest from camera for example, then it will soften as your camera moves into it in z (obviously!).Or do a higher rez paint plate

– comp the layers to be projected on in action by projecting them onto black layers (blackfill+whitematte)which are made simple add. you can then use masking and have as many layers as you need.

– patch areas up by using multiple projectors (combined with the matte paintings from different frames in the clip- ensure a new copy of the camera is used to parent with the only keyframe matching the clean frame)- in this case remember to use the lighting (hotkey “L”) function to link which projector is used with which images.

– for complex geometry (eg a sloping area), use a subdivided ext bicubic and align the relevant points to the track points in 3d space…a bit of a pain but when you get it right you get great results.

hope this all makes sense, i’m kind of just remembering what i do as i write. sorry it’s not a more well thought out description.

cheers

paul

[Anonymous]

This is great….mind if i add it as a tip in the tips section?

[Ramazan]

hi

yes that would be cool if you think it’s clear enough or should I do it properly and include an example with footage/screenshots?

paul

[Shane]

Thought you guys would get a kick out of this projection fix.

[url]ftp://scott:[email protected][/url]

[Isaac]

pokeitwithastick wrote:

Thought you guys would get a kick out of this projection fix.

[url]ftp://scott:[email protected][/url]

NICE!!!! it looks as though you are simply projecting onto bicubics with Gmasks on them and some primitives (rectangels; squares) and and a few other image planes…

really cool – really brought that flat shot of the kids room to life! it was looking like a real dog in the ‘before’ shot.

can’t wait to see more….

[bnw]

Yeah, that’s neat. Why is the ladder so far back in Z though? Didn’t it work at the nearer edge of the bed?

[Jacob]

pokeitwithastick wrote:

Thought you guys would get a kick out of this projection fix.

[url]ftp://scott:[email protected][/url]

hello,
looks accurate, awesome. Did you work with an FBX import or is it just about bins and bics and geoms placed in Flame (don’t see much axis) ?
thx for sharing

[Shane]

Hey Stefan-G

There were tons of axis. I just hid them to make the demo more viewable. I did mess up on the ladder being to far back in Z as someone mentioned but it still worked for my purposes. I tracked the shot using Boujou. Sorry Discreet. Then tried to place simple geometry from /usr/discreet/version#/models with deformers inside of Flame as acurately as possible based of of the reference image and my new tracked camera. The room itself was the inside of a cube with a deformer to slightly warp the angles of the walls to match the original camera lens warping. Boujou does a great job at finding approximate fov wich inside flame does do some lens distortion, so I only had to do minimal adjustments to the geometry. One key factor was to copy the exact position of the camera at the last frame to the projector. This way everything was lined up and was able to seemlesly transition to the rest of the unaltered shot. I hand painted the boy out so I had a clean frame and then added the boy back in as a card. The only extended bicubic was his foot and rear end which I had to warp to stick him to the floor otherwise he would float at certain angles. I used the extended bicubic grid resizer tip listed here on this site by Jeff Huesser. The warping actualy helped make it more natural because it made him look alive by sliding his foot.

Hope that helps.

Scott Balkcom

[Jacob]

Thanks Scott,

How long did it take to adjust all geoms (guessing you exported a .action file with selected axis – from boujou) ?

i usely try to get the camera (fov corrected) and some geoms to project on from the tracking department (adjusting position can be time consuming and doesn’t really need a Flame)
But anyway, i’ve had problems trying to change the layering priorities of multiple projectors (where proj2 will be behind proj1, invisible if smaller !!!), and didn’t find any option … so here is what finaly worked …
edit (jot) your .action, locate the projectors informations, (as i remember it is obvious, like “projector 1 … blah blah”)
change the order, cut/paste projector2 just before projector1 … save … open it again in action … done

don’t know if there is another way now, this was with a 8.5.2 Flame

if someone (i don’t know hog to do that kind of things) ever write a simple graphic interface to do this easier (and share it …) he/she will get loved

stefan

[Shane]

The whole shot including 3d camera tracking, painting a clean frame and aligning the geomtrey took about 3/4 of a day.

[Author]

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