Iray shader + intersections

mike9

Hello, I'm new to daz and have some problems getting decent results with a genesis 2 snake tail from daz and iray rendering.

Here is the tail with the default genesis 2 texture:

The texture is rather bad. I tried to use the strg+iray shader and not replacing the texture with this result:

Still not happy so next was a full replace without strg and a scale shader:

It loses the pattern but gives nice and sharp details yet the intersections are now visible and the left half is oriented to the right while the right halft is oriented to the left. I did some other experiments with more tiles to hide to orientation but it doesn't get better:

In another thread it was mentioned to increase the SubDivision Level for older models but it didn't change anything noticable for me and my understanding is its more for the gemetry details.

How can I hide the intersections/get all scales oriented in the same direction?

KurzonDax

Maybe I'm still a little fuzzy from eating too much turkey yesterday, but what are you referring to when you say "strg+iray shader"?

The source of the issue when you use the scale shader looks to me to be the UV mapping of the object.  Without generating a new UV map (in a 3rd party app like Blender or other modeling program), I'm not sure you can get away from the seams that you're seeing when you use a different texture.  The other option would be to create your own texture, using the UV template that should be available with the snake tail as a guide.   

mike9

KurzonDax said:

Maybe I'm still a little fuzzy from eating too much turkey yesterday, but what are you referring to when you say "strg+iray shader"?

The source of the issue when you use the scale shader looks to me to be the UV mapping of the object.  Without generating a new UV map (in a 3rd party app like Blender or other modeling program), I'm not sure you can get away from the seams that you're seeing when you use a different texture. 

The "strg" should be ctrl for the control key. Sorry about that, strg is what its called in my region and I forgot to translate it. That part was refering to pressing the control key while applying the shader to get the popup where one can select to not replace the original texture.

Concerning generating a new UV map: at the moment the tail in the map is split in two parts which creates probably the vertical line from the pictures above. If I merge it to one big UV map there should be still a horizontal line I wont be able to get rid of or am I missunderstanding something? The horizontal line I'm refering to:

It would solve the pattern direction but the horizontal intersection would remain for one side of the complete tail as the UV map is similar to a cone.

The other option would be to create your own texture, using the UV template that should be available with the snake tail as a guide.   

Is there a limit to the size of the UV map & texture in Daz? The template for the tail is currently 4096x4096.

 

Richard Haseltine

Do the UVs wrap, and does the texture tile? If the answer to either is no then you will get a seam just filling with a texture.

pvu05405 said:

Is there a limit to the size of the UV map & texture in Daz? The template for the tail is currently 4096x4096.

UV templates don't have a fixed size, or proportion. UVs work as ratios - (0,0) is the bottom left-corner of the image, (1,1) the top-right (ignoring tiling). If you are using tiling maps on a UV that is set up to use them then you can increase the repeats to get a higher effective resolution result from a lower resolution map (as long as it looks right shrunk and repeated).

mike9

Richard Haseltine said:

Do the UVs wrap, and does the texture tile? If the answer to either is no then you will get a seam just filling with a texture.

I probably can't post the original UV map but the tail has this shape in the UV map:

The right part gets attached to the left bottom. The texture file has the same shape. I don't know how it has to look like to determine if its a wrapping UV map or not. If the tiling texture part refers to it beeing seamless then yes the original texture for the tail is seamless but if I use a shader he ignores it.

Richard Haseltine

The problem is that a tiling texture meets smoothly at the edges of the map, not at the edges of an arbitrary region chopped out of it. You either need to manually edit the texture so that it does line up along the edges (which means you can't repeat it) or you need to adjust the UVs to have straight edges that match the repeat on the tiling texture (which will distort the pattern as the wdth changes). Getting a good look on something like this really needs a custom map. Because of the way you have the top half of the tail going down the map and the lower half going up your pattern is also going to switch direction at the join even if you make it match.

mike9

Richard Haseltine said:

The problem is that a tiling texture meets smoothly at the edges of the map, not at the edges of an arbitrary region chopped out of it. You either need to manually edit the texture so that it does line up along the edges (which means you can't repeat it) or you need to adjust the UVs to have straight edges that match the repeat on the tiling texture (which will distort the pattern as the wdth changes). Getting a good look on something like this really needs a custom map. Because of the way you have the top half of the tail going down the map and the lower half going up your pattern is also going to switch direction at the join even if you make it match.

Adjusting the UVs for straight edges would be to complex with my current knowledge. I will probably rotate or merge the right part of the tail to have one direction for the shader and experiment with the details to get the horizontal edge less noticable. Thanks for the explanation & help.