Nice! is it available? F.
2016-05-16 14:57 GMT-03:00 pedro santos <probi...@gmail.com>: > Does this help? > https://gfycat.com/ShabbySeriousDrafthorse > > On Sun, May 15, 2016 at 7:02 AM, Matt Lind <speye...@hotmail.com> wrote: > >> I would need to see the problem to give a good answer as I'm not sure what >> I'm envisioning in my head matches what is being described. >> >> Knowing how the sphere is modified is important. Unfold tries to evenly >> distribute the texture space of the texture to match the topology while >> minimizing stretch/compression. If the poles have elongated triangles, >> then that will obviously play into the distribution of the unfolded >> texture >> (in theory it shouldn't, but in practice it does). One way to mitigate >> that >> issue is to add vertices and perpendicular edges at regular intervals >> along >> the elongated edges to closely match the spacing of other edges around the >> rest of the mesh, but that will have limited influence on the result and >> is >> more of a brute force technique. >> >> Unfold is also a flawed tool as even simple cases come out distorted. for >> example, get a primitive sphere and imagine it's the Earth. Place a >> vertical UV seam down one side at the international date line, then two >> more >> seams at the arctic/antarctic circles. Deselect the vertical edges >> connecting the circles to the poles. Now unfold the mesh. Notice the >> sphere is splayed in butterfly fashion, but one half is larger than the >> other and slightly off kilter in alignment with the texture editor. The >> circle at one pole is often (but not always) larger than the other circle >> too. These are the kinds of issues you'll battle, but on more complex >> cases >> they'll be too complex to solve without resorting to cleanup via >> pushing/pulling points to correct the flawed parts of the unfold. >> >> However, let's put all that aside and look at the goal from the beginning >> and not the current situation which has a roadblock. >> >> An equirectangular projection comes in a few flavors, but most are similar >> to a cubic projection. The main difference is in how the top and bottom >> sides are projected. Simple analysis of the problem would suggest one >> could >> take a cube and use Catmull-Clark subdivision smoothing to round it into a >> sphere. That would accomplish nicer edge placement which closely match >> the >> meridians of the projection to handle (or fabricate) the texture space. A >> single vertical seam from pole to pole (despite no physical poles) could >> be >> used to unfold and splay the sphere to accept/define the projection, but >> subtle details may need to be tweaked for a perfect match. >> >> Alternately, use rendermap applied to a sphere to capture the external >> world. The rendermap generated image should mimic an equirectangular >> projection. You may have to open the poles like the Earth without the >> arctic/antarctic circles, for example, to adjust the field of view for the >> rendermap process. Invert the sphere's normals so rendermap points >> outwards >> into the world instead of inwards towards the sphere's surface....and of >> course, exclude self or make the material 100% transparent so it doesn't >> block the rendermap camera from seeing the world. Since rendermap travels >> texel-to-texel along the geometry, a high resolution image and smooth >> surface are really important. I'd encourage you to use a NURBS sphere >> with >> view dependent smoothing for best results. you set those in the sphere's >> geometry approximations PPG. Try setting length/distance/angle values to >> less than 2 degrees and 0.5 units, activate view dependent subdivision >> smoothing, and make sure the min/max subdivision limits are increased >> beyond >> the default 1,3 (well, just the max. shouldn't have to go beyond 6). If >> you get sawtoothing at the poles or faceting artifacts in the resulting >> texture, then it means your smoothing parameters are not set correctly. >> The >> reason for using NURBS over polygons is the better interpolation of the >> shading normal between texels. Rendermap is highly dependent on the >> shading >> normal orientation to determine what it's camera points at. When >> pointing a >> camera into the outside world, even very tiny deviations in normal >> orientation can produce big errors in the result. NURBS are infinitely >> smooth whereas polygons are only as smooth as they are subdivided - and >> even >> then approximations at best. >> >> Matt >> >> >> >> >> Date: Sat, 14 May 2016 17:33:32 +0200 >> From: "Sven Constable" <sixsi_l...@imagefront.de> >> Subject: RE: equirectangular uv >> To: <softimage@listproc.autodesk.com> >> >> To fix distortion on the poles, XSI has a special mapping feature called >> 'implicit' (Clusters/?Texture Projection Def), but this is actually a >> mental >> ray feature and doesn't deal with UVs at all. So when exporting meshes you >> cannot use it, I think. I'm not familiar with Unity unfortunatly, maybe >> there is a similar feature for spherical projections not using UVs but >> instead a special projection method (perfect spherical) ? >> >> Otherwise, since a sphere always has poles/singularities you will get >> distortions on them. Workaround could get rid of the poles by deleting the >> inmost polygons on each pole, duplicating the resulting (open) edge loop, >> and scale it to zero. Resulting in many point on the same spot. Then >> relaxing them in the texture editor. Results could be ok, not sure. Maybe >> I'm overcomplicating it. Matt Lind needs to chime in :) >> >> Can't you use cubic mapping? That should avoid the problem in the first >> place. >> >> >> >> sven >> >> ------ >> Softimage Mailing List. >> To unsubscribe, send a mail to softimage-requ...@listproc.autodesk.com >> with "unsubscribe" in the subject, and reply to confirm. >> > > > > -- > > > > *------------------------------[image: > http://i153.photobucket.com/albums/s202/animatics/probiner-sig.gif]Pedro > Alpiarça dos Santos >> http://probiner.xyz/ <http://probiner.xyz/> > <http://probiner.x10.mx/>* > > ------ > Softimage Mailing List. > To unsubscribe, send a mail to softimage-requ...@listproc.autodesk.com > with "unsubscribe" in the subject, and reply to confirm. > --
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