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Proyection mapping to a circular plane

vvvv beta question
#1

im having a few concers about if this is rigth or wrong,
the idea its to create a 360º screen with 3 proyectors. The circule its 3m diameter, each proyector its a 120º

i would like to map a texture around the whole circule using pixel blending, but im not sure how to calculate the distortion of each proyector.

any idea where to start ? my 1st aproach its to create a cilinder and to position 3 virtual cameras to 3 diferent renders, apply the texture on the cilinder, and map the image of each reander to the rigth proyector.

is this the good way to do it ? will 3 proyector provide too much distortion ? migth be 4 needed ?

#2

your approach is sound. Make sure, that you make the virtual cylinder the same size (e.g. every physical meter is one virtual unit) and position the virtual cameras and the physical projectors so they correspond spatially.

as for the last step (“map the image of each reander to the rigth proyector”) - if you do the first steps very cleanly [(node:Projector (EX9)](https://vvvv.org/documentation/(node:Projector-(EX9)) helps), you might not even need to map.
However, you might want to look into softedgeing the areas, where projectors overlap.

The count of the projectors depends on the quality of the projection you want to achieve, especially the size of individual projected pixels can vary greatly, if you use only 3 (its simple geometry, if you use 120° fov beamer, the ray of a border pixel becomes a tangent to your cylinder, so it will not be square and also much dimmer. also since pixels in the middle of the projected picture are much closer than pixels on the side borders, you might run into problems with aperture (i.e. some pixels are blurry).

I’d say 4 projectors (.8:1) should do the job, 5 projectors (1.0:1) have proven well for me.

#3

Great tip velrome, i did the tests and it worked exelent with Proyector (EX9) node, the only problem that i have now its to find the right projectors, the options on the Argentinian market are quite limitated, and i donw want to use 1.86,2.04 proyectors.

For a stand allone installation, what do you recomend for the cpu ? mother with 3 pcie or 2pcie + matrox ? i will be using 4 outputs + control monitor

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