Render image texture orientation

[Sean Casey]

Hi Guys, Hope you can help. I’m rendering an upholstered stool for a student of mine. She intends to use a fish scale patterned fabric. I have sourced a texture image to use to simulate the fish scale upholstery. I created the cushion using 2 arcs which I REGIONED and then EXTRUDED in AutoCAD 2010. I then FILLETTED the edge to create the radius over edge. When I attach the material as a texture in nXtRender and render, note how the pattern doesn’t wrap around the edge but instead looks like as separate strip of fabric orientated in the opposite direction to the top. Is this a AutoCAD issue or could I resolve it in nXtRender?

[George Ioannidis]

I am not sure if nXt could do that kind of texture mapping properly in all parts of your curvature. Some serious UV unwrapping is needed before you could apply the texture on it. There are several free programs which can do that, then you can export the result as OBJ or 3DS file and insert it into your DWG via nXt.

[Sean Casey]

Thanks for the feedback George. Should I have created it differently in AutoCAD in the first place? Maybe create the seat as a mesh or a surface so that when I added the texture map it would lie naturally and wrap around the shape as real fabric would.

[George Ioannidis]

It's all matter of try-and-error procedure Sean. I am not by any mean nXt guru, there are many others, really vastly experienced, nXt users surely willing to help you.

If I were you, I would export seat as a mesh, import it into Blender, unwrap it there marking seams (edges where mesh will be cut, think about it as an unfolding of paper model, this is quite similar process), then apply texture on it in UV editor. Finally export it back as a textured OBJ file ready to be inserted into AutoCAD. Unfortunatelly that is not a solution for you, as it requires some more advanced, mid-range knowledge of Blender. Sorry.

[Sean Casey]

I really appreciate you helping me George. I know it's normally a case of trial and error however unfortunately my student had a dead line to meet. I am assisting her with a competition and her entry has got to be in by next Thursday! She is an upholstery student and has no CAD skills. Think I might have to Photoshop it this time round but I do intend to explore other methods when using AUTOCAD and nxtrender. Many thanks for all your help.

[George Ioannidis]

For the sake of users solidarity I would like to try to make the mapping. If it's possible, please send me the model and the texture you want to apply on it. More heads, more brains (my grandma used to say) :D

[Peter Milner]

You may get a better result if you use planar mapping rather than box mapping.

[Roy Hirshkowitz]

There's no easy way to do this, in nXt or any other renderer.  Standard mappings won't work for complex wrappings.  George is right-- to do this perfectly you would need an application (not AutoCAD) that can do UV mapping where the mapping coordinates are stored on the mesh.  Since AutoCAD doesn't directly support texture coordinates on meshes, you would need to import the mesh using nXts OBJ import facility.

He and Peter are also correct in that it may be possible to get closer to what you want by fiddling with the standard box or planar mappings-- but it's absolutely trial and error and won't necessarily work.  In the standard box mapping the four sides wrap "correctly"-- the top and bottom do not.  In a planar mapping there is no wrapping, the texture simply projects and will distort quite a bit when the same mapping is used on perpendicular surfaces.