camera settings for projector

[Lennart Wåhlin]

No pun, just an observation, there must be something fundamental wrong
in your settings, like scale or projector settings.

Leaving all mathematics aside, if you have modeled your subjects
to scale and placed your camera in the scene where it should be in
real life, setting it to approx values, looking thru it and render, it should
maybe not match perfectly, but be in the area of close enough.

There should be no reason why the subjects should be way to big or small.

So, two things.
Check out how the zoom really works in the projector.

Then, the offset you are talking about (projector projects asymetrically
up, (north I suppose)) is the “FilmOffset” parameters in the Cinema Camera
Object.
The tech info for the projector, if I recall, states a +-16 degrees range for this.

Still, as mentioned before, as the Cinema camera is a pinhole camera,
no lens distortion is “made”. That sort of keystoneing has to be done
in the playback program. Or be made via a post app.

Most of my work is projection and LED content, but I must confess in a
much larger scale, so the projector side is handles by the projector/LED
contractors.
Still, no matter how much preparation , things are tweaked on site, both
contentwise and hardware.

Let us know how you are progressing.

Cheers
Lennart

aka tcastudios

[Nathan Byrne]

Lennart,

Thanks so much for helping me through this. I agree that I’m missing something fundamental here.

My thought is that scale problem must have something to do with the throw ratio of the lens. I tried a similar experiment with another projector and had a wildly different result.

My projector has a Throw Ratio of 2.00-2.40 and a Zoom Ratio of 1.2. I looked into the zoom, however the projected image was still much smaller than the real life object. Do you have any idea how the Throw Ration is related to the C4D camera? Is it already accounted for by the focal depth and the aperture?

I found a great projection calculator at projectioncentral.com I copied the specs:

https://download.yousendit.com/TTZsUXVrNXZkMnRjR0E9PQ

[Nathan Byrne]

Hmmm … I don’t know where to go from here.

[Lennart Wåhlin]

I frankly can’t tell how much help I can provide until
you have figured out the projector(s).

Try make a 1×1 meter square with a cross in it from corner to
corner and a circle in it.
Make it in Cinema and tape it on the (real) wall.

Test and check until you find out the proportions of your setup.

This is the prime way we do it. The designer and contractors provide
us with messurements, we then do “Default Nulls” and they confirm it.
Once the Nulls are perfect/confirmed we can start producing the content
having the nulls as our reference.

Cheers
Lennart

aka tcastudios

[Nathan Byrne]

Okay,

I’ve managed to get everything nicely aligned with a two dimentional chart. A couple of circles with an x through it. I also played around and made some nice 3D shapes play with the chart.

Yay. BTW to make this work, I set the correct information in SteadyDOF and then altered the Aperture Width to 18.3 in the object properties section.

Next step, make it work with a real world 3D shape where correct lens distortion fits correctly.

Nathan

[Lennart Wåhlin]

Good sport! 🙂
Now (or when you are pretty sure) nail those settings by settings keyframe
for all parameters at frame 0 so you don’t slip it!

And you must link to any final result, ok?

Cheers
Lennart

aka tcastudios

[Alex San agustin]

Hi everyone,

I´ve been carefully reading your discussion which is really interesting for me.
I have an important question related to projecting on 3d geometry and i suppose that will be interesting for someone else.

In most cases (like Nathan´s example), projector perspective and spectator´s viewpoint are the same, or are supposed to be equal. Then workflow is conceptually easy:

1. map reality
2. apply lens correction
3. make a 3d model
4. process it
5. render it (projector position) with lens correction
6. project it

Ok, but what happens when projector´s position and spectator´s viewpoint are not the same?
For example sometimes you have to work with several projectors that project on the same object. This problem can be solved by placing the projectors close together, then each perspective will be nearly the same.
Ok, but if projectors are placed in order to cover for example an sphere we are going to have 3 different perspectives: each projector perspective (that will be completely different) and spectator´s viewpoint…

This problem is solved here
https://www.vvvv.org/tiki-index.php?page=How+To+Project+On+3D+Geometry
by using vvvv , a real time 3d software… but, how can be this done in C4D?

Thanks a lot! this question is really making me crazy

Bye!!

[John Bone]

HI
I have been looking for your SteadyTOOLSv1 or even ANY DoF calculator online, cant seem to find one ? can anyone point me in the right direction as I have some C4D projection mapping to do and finding it difficult to sync my realtime projector with my virtual camera.

thanks!
JB