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.
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
check this forum for a terminal tool ( win and linux) that will convert a 16bit unsigned LSB or MSB image of a DEM to a spherical correct normalmap
the tool is called “NmTools-2.0pre2” ( normal map tools)
and a tutorial
for an EXAMPLE of using a normal map on a low resolution mesh
have a look at the end of this forum thread
the Asteroid Vesta
tips and tricks
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
hey JohnVV, AWESOME!! many thanks for your reply outlining this stunning workflow!
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 the Asteroid in the first post
i would start with a fractal generator and some “photoshop magick”
to make a DEM first
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
youtube vids- about 1 min.
– a test for nix–
– a test for hydra–
“celestialmatters” is the primary forum i am on these days
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?