hi there, i’ve been running into trouble texturing a sphere with seamless normal maps lately and made several approaches to get rid of the nasty seams with no luck as you can see.
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this asteroid is intended to be used in the blender-game-engine. the model is free-to-use CC 3.0 and maybe will be shared on blendswap if the seam - problem can be solved and there is a request for it. the actual .blend for download can be found here: asteroid.blend
are there any tricks, tips tutorials for seamless mapping you would point to worth reading regarding a solution for the seam - problems? is there a solution to get rid of the seams for this particular case?
beside that i am wondering about blenders unwrapping tool and why a UV sphere is not unwrapped symmetrical? marked a simple edge ring seam exactly in the middle and unwrapped it resulting in two not exactly similar face unwraps… normally they should be 100% similar shouldn’t they?
“beside that i am wondering about blenders unwrapping tool and why a UV sphere is not unwrapped symmetrical? marked a simple edge ring seam exactly in the middle and unwrapped it resulting in two not exactly similar face unwraps… normally they should be 100% similar shouldn’t they?”
I did this, and chose the middle vertex loop and marked it as a seam, 'U’nwrapped and chose Conformal in the F6 editor - bumped up my margin a bit to give some spacing, and it appeared to be the same on both islands. Did you perhaps unwrap after making geometry changes?
edit: I checked your file, and it appears you chose a vertex loop in the vertical mid line instead of the ‘equator’ as I did. The unwrap I did allows for the top and bottom poles to be the center of the face islands, so all faces radiate from those points.
alright craig - my fault, thanks for your reply! made a new normal map meanwhile and almost solved the seam issue which mostly seems to be related to a bad seamless texture…
I am still studying unwrapping as I go, as I tend to abuse Smart UV Unwrap and lose space sometimes. I then do a decent second unwrap and bake to my new UV map so I can compress image space. Anyway, do share your progress once you complete it
you will have issues with the poles IF the normal map is made for a FLAT PLAIN and not for a sphere
i make normapmaps for the 3d program Celestia
most people try to use a testure that is NOT mapped into a “Simple cylindrical” map projection
one that is a sixe of "power of 2 " and in 2:1 size ratio ( 4096x2048 pixels)
they normally try to use a unmapped “noise/ plasma” image – that dose not work
then the second “pit fall”
once you have a 16bit ( or 32 bit floating point) image
it needs to be converted to a "normal map " ( tangent normal )
you CAN NOT!!! use the Photoshop tool
nor the NVIDIA photoshop plugin
they MAP TO A FLAT PLAIN and not to a SPHERE
the poles will be WRONG
for exporting a UV displacement around a “small body” ( our solar system asteroids and small moons)
i make a sphere around the mesh
LARGER !!! than the mesh ( and write down the size )
say the mesh has a large dimension of 2 blender units
the sphere is 3
unwrap the sphere to to Spherical
set the “margin” on the bake tool to 21 ( works 99.9% of the time ) the default is 16
and bake the mesh to the sphere
this will bake a Displacement with NEGATIVE values
save as a 32bit float exr image
then use any math function in any terminal image editor ( vips, Imagemagick-Q32 , Gmic ) or the vips gui Nip2
and add the value of the sphere ( above +3)
now you have a DEM in blender units of the mesh
once you have a DEM in simple cylindrical mapping projection that is easy to convert into anything you need
No problem
i have been working on texturing spheres for 3d rendering for 10+ years
and found out the hardway that tools like the nvidia texture tools map to a flat plain
That causes problems at the poles
Now using a cube map ( AKA an environment map) and not a simple cylindrical can be done with nvidia’s texture tools .
you really DO need “seamless” textures
for example
for the Asteroid in the first post
i would start with a fractal generator and some “photoshop magick”
to make a DEM first
then
use walterVB’s MOLA/LOLA pds tool and do a direct import of the flat map to a 3d object ( the plugin dose the 3d Cartesian transform )
and sometimes mix that with a mesh from the " add / mesh / rock" add on
an example would be some of the moons of Pluto/Charon i just reworked
hey johnVV, thank you very much - your tips are appreciated and pretty professional. the workflow you depicted is impressive! (although i couldn’t fully comprehend some of the steps you are pointing to).
is the walterVB’s MOLA/LOLA pds tool also available for ubuntu? what stands DEM for?
