Can you tell me what projection is this?

NAIMA

Out of houdini , what projection is that and how can I do to convert to equirectangular? I did manually , but if I can find a more automated process would be nice...

https://i.ibb.co/bFv1XVT/gagarinheightmap.png

Eric Chadwick

What does it look like on the source? Context could provide clues.

This looks like maybe a dual paraboloid?

NAIMA

Its a planetary map , I am used to work on equirectangular, so this confuses me, the poles ar ein the half centers ... this is another similar map but more explanatory I guess...

Eric Chadwick

Ok that helps. It does indeed look like dual paraboloid mapping. Some info: http://www.bluevoid.com/opengl/sig99/advanced99/notes/node187.html

NAIMA

Thanks, is there a way to pass from this to equirectangular and viceversa?

Eric Chadwick

I’m going to guess… yes. But what software are you using? Houdini likely can do this. Substance Designer probably too. Blender could also, if you bake from a dual-paraboloid uv layout into an equirectangular one.

Eric Chadwick

Quad sphere. Two planar projections. Relax the UVs. 2nd object is a latlong sphere with spherical UVs. Bake from one to the other.

Eric Chadwick

Search is your friend, my friend! https://polycount.com/discussion/152716/dual-paraboloid-environment-map-to-from-cubemap

NAIMA

Eric Chadwick said:

I’m going to guess… yes. But what software are you using? Houdini likely can do this. Substance Designer probably too. Blender could also, if you bake from a dual-paraboloid uv layout into an equirectangular one.

I don't have houdini but I am trying to edit those maps that were made in houdini, I use other softwares and I also have g projector from Nasa but does't features dual paraboloid seems, I am not expert with blender.

In general this is not related to a model I only have the texture map and I wanted to make an alternative texture out of it .

I do have substance designer, though , is there a way to convert this?

NAIMA

Eric Chadwick said:

Search is your friend, my friend! https://polycount.com/discussion/152716/dual-paraboloid-environment-map-to-from-cubemap

Yes I saw that thread but , unless i am wrong I haven't found a tool that does directly this conversion .

Eric Chadwick

Why not just make your own textures, instead of using these low resolution ones, which may be restricted by copyright anyway?

NAIMA

Eric Chadwick said:

Why not just make your own textures, instead of using these low resolution ones, which may be restricted by copyright anyway?

Ok to be more specific in what I want to do , those ( not the one I posted ) are basically low resolution color maps from game starfield, I only have avilable a sea mask a surface mask ( dunno what's for ) and a color map for the biomes, so I know basically the sea and the color of the planet, I want to reconstruct the heightmap , which I did in the above grayscale image and then redo in larger size the planet with more details, features etc, I am good at making those usually ( the colored planet second picture I posted is custom made by me in this weird projection by hand , I had just to flip the bottom half two times and stuch to the side, make seamless then bring it back ) but its a tedious and labourious process so I would like to find something more quick that allows me to work in equirectangular as I am used to , do my work on them and then project back to that dual paraboloid version to make it work ingame .

Eric Chadwick

ok! This information would have helped in your initial post!

I would do this as a layered material in 3d, using 3d procedurals. Apply that on a sphere that has a dual-paraboloid UV, to bake down into a bitmap.

I did a similar thing with the planet in this, layering 3d procedurals and bitmaps, except baking the whole space scene into a cube map instead. But same basic idea. Great workflow, doing it all in 3d. https://ericchadwick.com/img/robot_rising.html#cubemapbackdrop

To make the dual-paraboloid UV layout, start with a quad sphere. Two planar UV projections, from front and from back. Relax the UVs. Tweak the UVs to match the wireframe here: http://www.bluevoid.com/opengl/sig99/advanced99/notes/node187.html

NAIMA

Eric Chadwick said:

ok! This information would have helped in your initial post!

I would do this as a layered material in 3d, using 3d procedurals. Apply that on a sphere that has a dual-paraboloid UV, to bake down into a bitmap.

I did a similar thing with the planet in this, layering 3d procedurals and bitmaps, except baking the whole space scene into a cube map instead. But same basic idea. Great workflow, doing it all in 3d. https://ericchadwick.com/img/robot_rising.html#cubemapbackdrop

To make the dual-paraboloid UV layout, start with a quad sphere. Two planar UV projections, from front and from back. Relax the UVs. Tweak the UVs to match the wireframe here: http://www.bluevoid.com/opengl/sig99/advanced99/notes/node187.html

Ok so there is no automatic tool ? .

Eric Chadwick

I think I figured it out. 

UV1:


UV2:


UV2 has some distortion at the poles, and you can see it omits a lot of the texture there. I guess you could rez up the sphere to reduce that.

Here's a glTF model with both UVs.

NAIMA

thankyou , what I usually do to correct distortion at poles when I work on equirectangular maps is to use hugin then I shift poles , export map , work on poles in z projection , reimport and redistort to equirectangular then I stich to original equirectangular. But I am not expert with this tool so I dunno how to adapt to change and shift dual paroboloid to equirectangular.

The fact that there might be distortions in equirectangular at poles is perfectly normal and it should be like this and I know how to work on that but I do not know how to work on dual paraboloid and turn back and forth workflow for it .

Basically all this is for modding the game so its not a work committment so the least easier and less time consuming the best haha.

Eric Chadwick

The best workflow then might be to just 3D paint directly onto a sphere that uses dual paraboloid uv. Then there’s no conversion needed.

NAIMA

Eric Chadwick said:

The best workflow then might be to just 3D paint directly onto a sphere that uses dual paraboloid uv. Then there’s no conversion needed.

This is not doable as its not a painting process but a several tools workflow I use to create maps .

gnoop

Why re-bake  to UV2?  .  This UV1  is the most efficient  use  of texture space  and geometry for both spheres and sky domes .   I do it same way for decades.    it could lod up to cube like shape,   basically a subdivided cube with a seam along equator ,   have proper distribution of texel size , mips  properly   etc.    just calculate  how many pixels you have that way along equator  vs  UV2 example of same resolution.

Eric Chadwick

Only because NAIMA has a texturing process that relies on equirectangular layout.

NAIMA

gnoop said:

Why re-bake  to UV2?  .  This UV1  is the most efficient  use  of texture space  and geometry for both spheres and sky domes .   I do it same way for decades.    it could lod up to cube like shape,   basically a subdivided cube with a seam along equator ,   have proper distribution of texel size , mips  properly   etc.    just calculate  how many pixels you have that way along equator  vs  UV2 example of same resolution.

Because most of the tools I use in my workout to make planets like those :

Is based on equirectangular maps , also Nasa source images are like so , I would like to find a tool or a workflow to turn dual paraboloid into rectangular, rework and then turn back to dual paraboloid.

If no tools are available, which to me seems very weird, could you make me a step by step guide for dumb noobs in may be 3dsmax or other tool to bake from one to the other?

I also had this tool hugin , I have a simple workflow to fix distorsion manually of the poles in the equirectangular maps but I am not enough proficient in it to implement dual paraboloid .

https://hugin.sourceforge.io/

gnoop

Every 3d package texture baker  could bake  from one UV to another   or from one mesh to another.  Could be done both ways  actually.  I don't use 3d max  for a decade  already  but as far  as I remember it could be perfectly done in render-to-texture dialog.

Or any texture baker  that support  a texture on "hires" mesh.  Substance Designer for example.    

Quick find:   https://youtu.be/dBwGjJjd_M8

I haven't seen it through but youtube have gazillion of tutorials about baking. Not sure why it's 30 min for so simple thing.  I usually don't have time to see anything longer than 15 min

Well maybe rather this:

https://youtu.be/1HyexrUEIv0

Still lots of  redundant info, sorry.

in short  using Blender  you need to just add a second UVMap.001  . unwrap it to your liking,  drop and select target  texture in shader pane  and hit bake  while  UVMap ( original one  still having render "camera" mark  on  and UVmap.001 selected .

it's for one UV to another UV baking .   

Since you probably would like to bake   not just other UV but rather other object it's like selecting  first object  then  shift select target object placed in same space , Hit "bake"  with "selected to active" checkbox checked in.   Same way the target texture  should be dropped  into shader pane and be selected .

You may need to play with extrusion and max ray distance values in the baker . They are like invisible cage  setting  ray distances  outside and inside  target (active) object.

 You can select them in outliner too .   Active (target) object is one highlighted brighter.

Eric Chadwick

It's pretty easy to bake in Max, if that's what you have or prefer. 

1. Select the model with two UV channels on it (like my glTF example).
2. In the Material Editor, add a Bitmap node, and load your equirect map. 
3. Set the map channel in the Bitmap node to the equirect UV layout (channel 2 in my example). 
4. Add a Physical Material, and connect the Bitmap into the Base Color Map input.
5. Assign the material to your model. 
6. Rendering menu, Bake To Texture (or press the zero key)
7. Select "Color" under Common Maps, click on "+ Add Maps To Selected Objects".
8. Set the UV channel you want to bake into (1 in my example).
9. Set the output resolution, 2k by default.
10. I always change Padding to the max value 128.
11. Set the file name you want to save, and the format.
12. Set the Output Path where it should be saved.
13. Bake. Takes about 30 secs on my machine.

Seems like a lot of steps but it's not, goes pretty fast.

There are a couple commercial glTF importers available for Max, with free trial periods:

• SimLab https://www.simlab-soft.com/3d-plugins/GLTF-to-3DS-main.aspx?locale=en
• Satoshi Hayashi https://nu1963u.wixsite.com/custom3dsmax/gltfpluginfor3dsmax