[feynman]

Hi,

new to Rhino, so I may well be missing something glaringly obvious. I'm trying to create books - with U-shaped dust jacket surfaces - and whatever I do, I can't get PNGs/TIFs/JPGs to wrap around such U-shaped rail surfaces correctly. I have also tried such almost idiotically simple shape in Pro/E and Catia, exporting via IGES to Rhino to output OBJs from there. In Rhino I chose Texture Mapping > Custom > Surface and then export the rail surface an OBJ. I have also extruded an U-shaped curve in Rhino directly and output that as OBJ. The thing is, in Alias Automotive or Catia V5 surface mapping works by changing the parameterisation of the surface from uniform to chord length parameterisation and rebuilding multi-knots on the curve - the rail surfaces created there renders in these softwares without surface mapped textures being stretched. But of course: I want to render in Maxwell Studio :)

Autodesk: "Surface textures are mapped to a surface’s parametric space. That is, the XY values of the texture are mapped to the UV parameters of the surface. If the surface’s UV parameterization is non-uniform (that is, the U and V isoparametric curves are not uniformly spaced), then the texture appears distorted. This often occurs when mapping a surface texture to a curved surface. The greater the surface curvature, the less uniform the parameterization, and the greater the texture distortion."

Thanks in advance for putting me on the right track!

[JDHill]

Not sure what you're dealing with there, it looks more like you're using a box mapping. I created a similar surface and a texture corresponding to its dimensions, and it maps fine using the default surface mapping:

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If you send me (jeremy at nextlimit dotcom) your .3DM, I can take a look.

[feynman]

Thanks JD, that is most peculiar! I did not use a box mapping as that won't wrap xy > uv. So, thanks for your kind offer, I e-mail you a 3DM with three dust jackets from other softwares including one from Rhino...

I've just e-mailed a 3DM file and a small image.

PS: in some old forum post, I just found this, relating to surface texture mapping: "That is if you use "Control Point Curve", but if you use "Curve: Interpolate Points" then the problem dissapears!". Maybe this means something, although I don't understand what the technicalities of the latter are when a mesh for rendering is output.

[JDHill]

I just emailed you a model showing two approaches for dealing with this: using Rebuild on the curve, or constructing the geometry from five joined curves (three lines, two fillets), rather than as a single curve:

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[feynman]

Cheers, JD! That's how it should be done. I discovered that it is possible in Alias/Catia/etc. to parameterise a surface with uniform instead of chord length knot spacing; this will (transformed into OBJ via Rhino or done in Rhino as you show) surface texture map as expected. Your >5 curves approach is probably best to make the spines of books more detailed and used looking. If you need some 3D books, just let me know :)

Covers


Paper blocks


Tessellation from Rhino