Hi,
I made some Fulldome Graphics and just have a little inaccuracy in the unwrapping of a dome.
The best solution I have found yet is a Quadsphere from Machinetools and than just unwrap it.
The Problem is… it is ok but it is not accurate…
From far away it looks good…
However… the devil is in the detail and it looks like this actually
Does anyhone has an Idea, how to very accurately create and unwrap a Dome for Fulldome Fotage in Blender?
From a brief search on Wikipedia on the meaning of fulldome graphics, I am guessing (and I will love that you show me where I am wrong, as I should be) that it is some kind of texture changes at the surface of a sphere.
For the unwrap problem you are facing, does it help if you used the primitive UV Sphere with its default UV Map, so you do not need to unwrap.
If my answer has no relationship to your question, I would appreciate that you leave an explanation or some link to one about what you mean by Fulldome graphics … Fulldome foootage
Fulldome is a format that is used in planetariums/mediadomes …
We have Half a sphere at the ceiling and a group of projectors, sometimes 4, sometimes 2… like that. project an image to that half-sphere…
The Images themselfs are basicly Fisheye Images, like you record with a Go Pro… Or like you render with Blender Cycles Fisheye Camera Settings…
Here is an Example Image
And this is what it is supposed to look like on a dome… minus that little black borders in the curve.
So my Problem is, I would like to get rid of the Black Borders, that are very uneven…
To get it really spherical:
Another thing is that your fisheye should better not be surrounded by black but rather extend the colors of your fisheyes outer colorvalues.
As I understand it, this makes meshes spherical.
The Problem is, my mesh is already spherical,
The UV´s are the problematic part
You shall use it on your uvmesh. It works there aswell. If I get you right then you have fisheye images at hand and want to align the uv mesh. The fisheyes border is completely spherical but your uv not. Thats why you select the verts/ edges at the outer edge of your almost circular uv mesh an make it circular like I wrote.
In UV I dont have To Sphere in the F3 Menu…
Edit: deleted the last bit, since it wasn’t THE Solution after all…
I doubt it’s a well-aligned mesh. 
Of course, there might have been a problem during the uvunwrap process.
I added a video above. I’ ll have a look if its an addon, but I am pretty sure its builtin. Gimme a moment.
Yes, this is proably not… this a a Quadsphere from MachineTools.
However, I have a similar problem with UVSpheres…
This a Normal UV Sphere of Blender, no changes except that it was cut in half…
Shouldn’t it be perfectly aligned and perfectly spherical?
Ok this helped a little bit.
However, I noticed something else…
On the left Side it overlaps a little bit into one direction
and on the other Side it is the opposite…
Ok found it. Its builtin, but to see there aswell it you have to enable
Preferences → Interface → Developer Extras
Regarding your last question, then the mesh or the image isnt perfectly centered. So you can eg just move the whole uvmesh a tad to the right.
I tried 2 Images,
Both to the excact same resolut. So the Image is fine.
Regarding the Mesh,
Like I said… I only use the Blender Builtin Sphere Meshes…
No further manipulation, except cutting it in half…
I will look into the developer extra thing you showed me.
Ok if you checked the image then it shouldnt be that, fine.
What, the uv mesh? No. Its dependent on the algorithm used to unwrap. And the alignment is also rather very seldom right in the center. Typically you have more than one uv island. And what you show there arent blenders default uvs you unwrapped it to be like that.
But simply check to most left and most right uv values to see if its off.
Well I just pressed u and selected unwrap… The Blender Built-In Method to unwrap… I thought, this should do the job.
Ok, i rotate the UV around its center and the gapchanges, gets bigger and smaller. I think it means, that the Unwrap if faulty…
I will try some Unwarp Addon for this, if there is no Built-In Solution for excact unwrapping.
Cant say much to that. It depends on so many things. Is eg your sphere really axial symmetrical on a mesh level, what its not if eg you chose an uneven vertcount, then it will already start to be slightly off. Just made a short test here and its off at the third decimal place. Should be fine to align with the typical texture resolution, the difference might be due to numerical floating point reasons.
What you use here is a generic unwrapping, not procedural uvs. So its not faulty. Its the result of an algorithm that tries to minimize the angular distortion over all faces.
If you see that the center is off, then use the uv mapping tools at hand to fix it.
Its as i said from the beginning. Do a To Sphere, center it and you’re done.
I doubt you’ll find an addon that will make you happy in this regard. You can do a projection mapping but that will leave you back with other problems. You can use Geometry Nodes and generate the UVs, or do a manual tweak of the mapping you have.
I fundamentally question whether it is possible to perfect this.
Because when we do uvunwrap, we put a little bit of space on the image outside of UV to solve this problem.
Well there is a point depending on the given the texture resolution and mesh density where a perfect circle is well enough approximated by the mesh to hit the right pixels along the circular border. But the distribution of the inside also has to fit to what the camera lens did with the fisheye. But to make it short LCSM and related algorithms arent built to deliver perfect spheres. Its just a speciial case. Doing it in a proecedural way would be the best fit.
