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View Full Version : Complex 3D cityscape camera projection, need some advise


Fanko
08-29-2010, 11:12 AM
I am currently working on a challenging project, that involves a large scale cityscape camera projection. Basically, I need to do a few shots from a moving train perspective as you watch the cityscape flyby.

This is the first time I do this, so I am not too sure how to approach it.

I want to experiment a little, so I acquired a high rez panoramic photo plate of a cityscape and try to building some 3d geometry so I can project onto and try out a camera move and see how it looks.

http://img710.imageshack.us/img710/...attannewyor.jpg (http://img710.imageshack.us/img710/7807/brooklynmanhattannewyor.jpg)

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And the first problem struck me, I cant seem to get the Focal length right to match the perspective of the photo. May be because panorama always consist of many different photo, so its impossible to get the perspective right?

Then I thought may be I have to slice up the photo plate and do 3-4 horizon camera projection?

I am still not a professional when it comes to camera projection, so I am still trying to figure out an efficient way to do this.

I would like to hear some advice from professional how they will go about doing this.

Any advice will help :)

If you are interested, I can actually show you the rough cut of the film to give you a better idea.

nickmarshallvfx
08-30-2010, 08:41 AM
I'd be interested to hear any advice on this too. I've yet to try matching a camera from a stitched pano, but I can see the problems it would hold...

Fanko
08-30-2010, 11:02 AM
i actually done it with some experiment.

I just have to make sure there is no lens distortion from plate and the maya camera focal length has to match the one used to take the photo.

May be it will be a individual case, but the panoramic plate I am using now is working so far.

nickmarshallvfx
09-05-2010, 11:14 AM
Cool, so are you still projecting from multiple cameras using the delensed plates, or did you stitch them together into one plate? Look forward to seeing the results!

Nick

Fanko
09-07-2010, 02:29 AM
I projected the entire pano with a single camera, and after finding out the correct focal length, I had no trouble with perspective.

Another challenging task was building the basic geometry for projection, the plate has at least 40 buildings visible, with many more partially hidden ones. I had to be extremely cautious with their placement, since every buildings are relative to each other, and you can easily mis-align the relative position of the buildings on one side of the plate while you are working on the other.

Since its a pretty wide pano plate, I had to constantly zoom in and out to get each block match up. I guess you can imagine the headache this can give you.

I will be happy to show it to you when the film is completed.

halen
09-07-2010, 08:51 PM
uhm. If the train is moving ain't there a problem, since perspective constantly changes? I mean you should constantly see new houses emerging behind old ones? Sticking panorama from images taken from one point of view feels like possible difficulties. How do they do those things where camera goes 360 around something - for example building - and you still have to see background changing accordingly?

I was thinking that in some places it might help to "cheat" somehow - like making the train go pass something like trees, close by buildings, tunnels, billboards or something to get a change to change the image and not to do whole slow transformation of perspective.

Fanko
09-07-2010, 09:17 PM
Thats right, "cyclonomaric" matte painting doesn't apply in this case because the camera is traveling in a direction.

although time consuming, all I need to do is patch up the buildings that are showing behind the buildings that are originally partially hidden in the pano plate.

Franklin

halen
09-08-2010, 11:30 AM
although time consuming, all I need to do is patch up the buildings that are showing behind the buildings that are originally partially hidden in the pano plate.

I was just thinking exactly that and had one of those tedious moments when you realize the amount of repetitive work to be done and see no way to weasel out from it. :thumbsup:

Fanko
09-08-2010, 08:33 PM
yup, I am afraid so. :(

but I will try to do the patch up as effective as possible.

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