[caryjames]

Hi guys... I have tried and tried ... and tried to get a steel rope material to work but I am hitting a lot of walls and at this point I can not tell if I have a texture projection issue going on or something else. Could one of you guys have a look at this and give me some insight. I would like to create my own steel rope material but I think to be successful I need to get one from the gallery to work and I am having difficulty in even getting Kurt's beautiful steel rope material to work.

Here is the download link to Kurt's material

http://resources.maxwellrender.com/sear ... v2=0&tipo=

I have applied his mat to a 10mm tube as he directs in his instructions but I am getting results that vary drastically from his posted image. I would have contacted Kurt directly but I think I am having difficulty with Rhino specific texture mapping



I would include a 3dm file of my scene but it is only a 10mm diameter tube (I have tried it with no wall thickness and with a 1mm thick wall and I always get similar results) and I figured that it would take you longer to download the link than it would to just create another 10mm tube and a flat plane for it to sit on. I have also tried different projections... the image shown is of a planar projection directly from overhead.

Can one of you guys take a look at this material and see if you can get it to work on a 10mm tube? I will need to scale the material but I think I need to get it working correctly on a 10mm tube first before I start to make any changes.

Thanks!!!!
Cary

[JDHill]

Hi Cary, it's possible to do this in Rhino:

1. set all texture tile x/y in the material to ~3.0
2. set displacement to ~0.1 cm
3. give the object a custom mesh setting with Maximum Edge Length of ~1.0
4. give the object a cylindrical projection
5. reset all the projector values (i.e. size 1.0, position 0.0, rotation 0.0, etc.)
6. click 'Show Mapping' in Rhino so you can position the projector
7. rotate the projector so it's aligned with the tube
8. set the projector's z size to ~30.0

Clicking through the various assigned textures (in the plugin material editor), you should be able to confirm that the textures are mapped pretty good now - here's how it looks rendered here:



Obviously, you may want to adjust the tiling, depending on how the rope is supposed to look. This was done using a 10mm-diameter cylinder, with document units set to millimeters. If your rope is going to be curved, then there will be some degradation, as the cylindrical mapping cannot also be curved.

[caryjames]

Thanks for your step by step description JD for some reason I am still in a world of hurt.... here is a screen shot showing my settings followed by a quick render of the results. I did orient the projector along the length of the cable but did not get a twist to the wire so I rotated it a little to try and obtain the correct results from the render view on the perspective viewport it looks like things will work but boy are they off. I am a bit surprised at how finicky it is to get this material correct... it is really hard to look at your rendered image and be able to isolate where the material needs to be tweaked.... is the tiling off, am I using the correct projection... I know and understand how to use all of these 'tools' but when the rendered image looks substantially different from what you are expecting I find it almost impossible to be able to troubleshoot and isolate where to tweak. How do you look at a rendered image that looks like mine here and know where to start modifying your material?





Any thoughts as to where I am going wrong? Thanks as usual in advance!!!!!!!!!!!
Cary

[JDHill]

Yes, mainly, your projector is grossly misaligned with the object you're mapping - what's happening is that you are showing the wrong map in the viewport and are therefore trying to adjust the projector wrongly for this material. So, open the material editor, select the rope material, and then left-click on the displacement map's thumbnail button so that it is shown in the viewport. As you'll see, that map is very different from the ones being used for reflectance and bump - the projector needs to be brought parallel with the object, such that the reflectance and bump textures are mapped as straight lines running along the length of the object, rather than crossing it diagonally.

Let me know if that gets you anywhere, or if you'd prefer I post a couple of screenshots.

[caryjames]

Hi JD- sorry to be obtuse about this... I think I have it set up as per your instructions but am still getting vastly different results. Can you have a look and let me know what you think I am doing incorrectly? THANKS!

[JDHill]

No worries, it's a bit of an abstract topic. When I say align the projector, here's what I mean:



On the left, the displacement map is active in the viewport, and in the right, the bump map. You're most nearly there already - you just need to align the central axis of the cylindrical projector with that of the object, rather than having it raised up 57.363mm in the z. Keep in mind that conceptually, a cylindrical projector 'shoots' each texture pixel from the center of the projector outward.

[caryjames]

Oh man thanks JD... I still have to wrap my head - no pun intended- around this texture mapping issue. Usually I am assigning a simple brushed texture or maybe some simple wood materials so it has been easy to see where you need to adjust, but this steel rope material has really been a lesson in frustration. I am running a test now to see if I am in the ballpark... thanks for your patience! O.K. Here is the result of that test... closer I think but still off.




Cary

[EADC]

Hi Cary,

Just tested this, and noticed that in order to get this to work, you need to 're-activate' displacement in Kurt's material. Just 'add' displacement and all proper settings come back. Then adjust mesh max length as JD says, set displacement to .3 mm, play with the displacement 'tile Y' mapping a bit and it works. Below a cable of 10 mm. No need for cylindrical mapping, surface mapping works fine, also on curved cables.


curved cables:


Eric.

edit; assumed you work with 2.0

[caryjames]

Thanks EADC- I am actually getting close, I am still using JD's technique - I had my projector scaled for a longer tube that I then cropped (because the mesh was so large) but I did not scale my projector to match, pretty bonehead move I don't know what I was thinking! I will post results once I have it set up. Thanks both of you guys for your help!
Cary

[caryjames]

Hi again guys- this is close but still something is off... I have all my settings same as JD's instructions.

1. set all texture tile x/y in the material to ~3.0
2. set displacement to ~0.1 cm
3. give the object a custom mesh setting with Maximum Edge Length of ~1.0
4. give the object a cylindrical projection
5. reset all the projector values (i.e. size 1.0, position 0.0, rotation 0.0, etc.)
6. click 'Show Mapping' in Rhino so you can position the projector
7. rotate the projector so it's aligned with the tube
8. set the projector's z size to ~30.0

Can you guys see where I am going wrong? Thanks!

[JDHill]

Do you have the displacement height set to 0.1cm or 0.1%?

[caryjames]

Hallelujah! Thanks JD and EADC - JD I did forget to tick the absolute units, but for some reason my displacement map was also inverted which was causing a scooped appearance. Once I inverted the map and checked absolute units it worked..... MAN this was a challenge but I finally have a better grasp over the mapping and displacement. Thanks for your patience ... now I have to see if I can create my own custom rope material . THANKS!!!!!!!!!!

[caryjames]

Just when you thought it was safe... O.K. I can get the steel rope texture to work on a straight piece of cable but when I try to apply it to a curved tube everything goes out the door. The cylindrical projection does not give the required look so I have been experimenting with a planar map but am having absolutely no luck- the rope just does not have the same twist. Can you guys have a look and advise- thanks!

[caryjames]

Is there any way to make the cylindrical projector "flow" along the cable?



OR is there any way of using multiple projectors on the same cable to seamlessly project the texture?

[JDHill]

No, as I said in my first post, you can't curve a cylindrical projector. I think that in Rhino 5, you are supposed to be able to use a piece of geometry as a texture projector, so it might be possible there. Nevertheless, it is entirely possible to forego the use of projectors altogether - in which case you are using a 'surface' mapping. The drawback here would be that you will need to adjust the tile x/y values in the material, and therefore, you may require a separate material for each differently-sized piece of rope you are making. Keep in mind, if you try this, that the U/V directions of your surface may run the wrong direction by default, and you would need to (a) explode the pipe, in the case that it is a capped polysurface, and (b) run Dir > SwapUV on it to get the UVs oriented appropriately.