Mapping logic help?

[paralion]

Not really a resolume issue, more of a logical or optical one... I guess.

So I'm trying to map 4 projectors on a square wall.
Really having problems with the upper left projector, trying to map the output.

Upper half is projector 1,lower half projector 2.

As you can see in circle 1,the upper squares are smaller than the lower ones, and in circle 2 to the right it's the other way round. So if I fix it on the right, it will be wrong on the left and vice versa. How can I fix it, does it have to do with the physical position of the beamer?

[He2neg]

Its kind of keystone (horizontal) The lower projector is not looking straight to the wall but angeld to the left... (or the other one to the right xD)
But i also think you allready mapped a lot so its not easy to tell from just the result what is wrong now...

In generall.... first do everything you can to allign everything physical moving the projectors (+ modest shifting) use some grip test pattern to get a good view.

after this you can use Arena as software solution to get the last bit perfect...

[Zoltán]

If you can, avoid using the projector's keystone adjustments, unless they are done via the optics. That's often not nice, if you also have to correct in Resolume.
Lens shift is no problem.

If you try to blend these, I'd also recommend a bigger overlap. https://resolume.com/support/en/edge-blending

And if the wall is not flat, you can split up the slice into more points and use the bezier mode. https://resolume.com/support/en/output- ... on#warping But you really shouldn't need this on a flat surface.

Also check out the difference between perspective and linear warping.

[paralion]

The wall is flat and square, so I should not have to use warp.

On the bottom beamers I have to use trapezoid correction, because the default lens shift is 30 cm above ground and I need the projection to be starting at the bottom. (so I have to tilt them downwards and the picture will get distorted, so that i have to use the trapezoid)
On the top ones I also used it, because i thought its better if they all have the same correction. Maybe I could try to position the top beamers 30cm lower, and have no trapezoid correction on them.

Thanks for the tips, very helpful!

[Zoltán]

Arena can do the trapezoid correction for you, probably better than the projector.
If you can get the projectors aligned so their images overlap, you can do the blend and other corrections in Arena.