How to get a decent spherical uv map?

[Krion]

Hi! 

I get this distorted thing on top of my sphere mapping, and I do just the same as in the in the example on this link, with the same texture:

https://wordpress.discretization.de/houdini/home/advanced-2/textures/

But mine looks like this:

Why is this and how would one do this? 

Also: How would one best uv-map a sphere when using, say, a pattern VOP in a material instead of such a texture map?

 

Thanks in advance!

phereMapping.hipnc (here is the texture)

 

Edited September 29, 2019 by Krion

[StepbyStepVFX]

Works better if you subdivide your geo prior to unwrap your uv in polar coordinates.

That being said, there is still an issue, and it is probably due to the unwrapping and layout of uv.

phereMapping-3_v2.hipnc

Edited September 29, 2019 by StepbyStepVFX

[StepbyStepVFX]

By the way, thinking again on your problem : your image is a latlong map. You could also convert it as a cross image using isixpack (https://www.sidefx.com/docs/houdini/ref/utils/isixpack.html).

Then, instead of unwrapping uv with polar coordinates on your « spherized » cube, unwrap your cube and make each faces’s uv match the cross image....

[Krion]

What do you mean with a latlong map? When I google I find out about longitude and latitude, which is like x and y(?). Do you mean it is a map which consists of just one plane?

Thanks again.  

[StepbyStepVFX]

Here are examples of various environnement maps formats : angular map, cross, latitude-longitude (latlong)

http://gl.ict.usc.edu/HDRShop/tutorial/tutorial04.php