algorithmic@gmx.at

for an installation i want to project with 3 projectors on the surface of a hemisphere (one half side of a globe). i tried out a small patch in vvvv using the "projektor node" (works like a virtual camera) but i would much more prefer to use max/jitter.

does anyone of you have experience projecting on a globe/sphere? how do you solve the problem with the distortion?

is there a similar object in jitter like the "projektor node" in vvvv? a virtual camera which which "films" a virtual globe from a certain point, the output to the video projector should be exactly the "real" texture of the globe?

or does anyone have a better idea to program all this? i haven't tried out yet if it works - just in virtual in vvvv.

uff, it's even difficult for me to explain my problem (in Englisher), so you'll find attached a jpg of the vvvv patch for better understanding... maybe someone of you can help me, would be great! 

for an installation i want to project with 3 projectors on the surface of a hemisphere (one half side of a globe). i tried out a small patch in vvvv using the "projektor node" (works like a virtual camera) but i would much more prefer to use max/jitter. 

uff, it's even difficult for me to explain my problem (in Englisher), so you'll find attached a jpg of the vvvv patch for better understanding... maybe someone of you can help me, would be great! 
thanks so much!


projecting-on-a-globe-hemisphere

you could use jit.gl.gridshape @shape sphere and texcoordmagic patch...(look for it n the forum you should find it easily) to place the image in the geometry.

hello,
you could use jit.gl.gridshape @shape sphere and texcoordmagic patch...(look for it n the forum you should find it easily) to place the image in the geometry.
Cheers
Hubert


Also look at the tex_map attribute when you're applying a texture to a sphere, there are 4 options and one should work, possibly in combination with some other parameters.

also texcoord magic only works on tex_map 1 and 3 I think

Also trying to map a hemisphere with a radial texture, I can't find the texcoord magic patch you are are talking about.

Could anyone advise me where to find it? or lead me to a text_map example?

hi,
Also trying to map a hemisphere with a radial texture, I can't find the texcoord magic patch you are are talking about.
Could anyone advise me where to find it? or lead me to a text_map example?
thanks a lot


did you try searching the forum for "texcoord magic"? it comes up if you do.

did you try searching the forum for "texcoord magic"?  it comes up if you do.


yes , sorry, found it, I mistyped my search.

i think this is the texcoord magic patch...

marc, do you know how to handle the problem with image-distortion when projecting with multiple videoprojectors on a hemisphere? i have the problem that i can not project that way that all projectors output the texture for the whole surface of the hemisphere whithout DIFFERENT distortion on the borders/edges of the projector-images...

i think this is the texcoord magic patch...
marc, do you know how to handle the problem with image-distortion when projecting with multiple videoprojectors on a hemisphere? i have the problem that i can not project that way that all projectors output the texture for the whole surface of the hemisphere whithout DIFFERENT distortion on the borders/edges of the projector-images...

hmmm, that's an interesting question, and does not seem related to texture mapping so much.

you're never going to get rid of distortion entirely because your projecting a rectangular image (your output window) onto a spherical surface. my first guess is that you don't need to to software based spherical mapping, because your are doing actual spherical mapping when you project. i would also guess that having corner-pin gl.mesh/gl.nurbs setups would allow you to achieve an acceptable mapping of each third/quadrant/whatever of the sphere.

however this is all conjecture, as i've never tried.

edit: actually, rereading, i'm still not quite sure i understand what you're asking, but am interested to hear what solutions you come up with.

you're never going to get rid of distortion entirely because your projecting a rectangular image (your output window) onto a spherical surface.  my first guess is that you don't need to to software based spherical mapping, because your are doing actual spherical mapping when you project.  i would also guess that having corner-pin gl.mesh/gl.nurbs setups would allow you to achieve an acceptable mapping of each third/quadrant/whatever of the sphere.

edit: actually, rereading, i'm still not quite sure i understand what you're asking, but am interested to hear what solutions you come up with.


there was a shader that someone made that did pretty good projection textures

cool, could you tell us how/where to get it..?

projecting on a globe / hemisphere