garageCube

[Lumenarius]

We have been working with geodesic domes and projection mapping for years and are finally getting pretty decent with the results.

Depending on the dome and the specific setup there are a few ways to do it. With this post I would like to touch on the method we used and also see if there are any other ways to do it.

First of all we are using multiple projectors. In this case I am showing we used x7 projectors with a 1:1.09 throw.

We then had a "flat" image of the dome struts as a test pattern. This dome had the membrane on the outside so we could leverage the cool architecture and have something to map onto.

The trick is to use enough mesh warping points to adjust all of the triangles and get them super precise. This can be tricky as the mesh warping is in a rectilinear grid while most all geodesic domes are an icosahedral grid. If you throw enough points at it you will eventually get super close.

When it comes to blending the projections either the "soft-edge" approach or blending them along the struts seems to work great.

See attached photo.

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Okay, next steps.

The above approach can work well though it can also take HOURS.

I have been researching some other ways of doing this and it seems the automatic camera blending is a good way to go. But! Most of these approaches use walled garden types of hardware and software. Specifically proprietary cameras, hardware, and software. I get it is very specific but not being able to easily pipe in a Syphon feed is not cool!

With that in mind does the MadMapper team, or any other user, have a way to achieve any kind of camera based automatic calibration for full domes with a camera?

I recall there is the MadMapper Spacial Scanner but IIRC that does not handle multiple projectors for a dome per se.

Anyways, just thought I would put these threads out there for those in the future. If we improve on the technique we will post here.

Cheers!

[mad-matt]

We haven't planned to handle dome projection. We have other priorities at the moment. Thanks for sharing your tips!

[Lumenarius]

It's all good. This is literally the only edge case we have found where MadMapper is not better than every other software solution out there.

For domes where the struts are present it definitely still works if you blend along the struts.

For domes with a featureless smooth liner it is not suitable.

Totally get you are working on other things. I can only imagine that camera based calibration is a very difficult programming job.

However, if it could be included in the future such that MM would automatically blend N projectors using N cameras (on domes or other complex geometry) it would be worth the world! Maybe it could be purchased as a separate add-on like the laser and projector control modules?

Either way, thank you Matt and keep building!

[Lumenarius]

For anyone else in the future here is an image of how the mesh warping was applied to the slice of the dome.

Given you have to apply a square mesh warping grid to a non-square dome grid you will have more points in some areas and less in others. You can always add more with a right-click add point if not enough.

Definitely tedious but worth it! Plus, if you use the same projector layout in the future most of the work is done.