Different colors in Rhino rendering?

[henrikb]

Is it possible to put for example a water line or a colored area on a surface when renderinmg in Rhino (flamingo render), without splitting the surface into different parts?

[CGN]

you can use texture mapping, search in the help on how to use this feature, it usually works fine with most polygon modelers, i render using an external software

[henrikb]

Thank you very much!

[duluthboats]

I have also found it a pain doing things like water lines and mapping for me hasn’t been any faster. With the water line like this one I end up cutting big surfaces into many small ones.
Gary

[CGN]

Yes is tricky to use and i remember when i started using rhino it was not possible to "map" 2 diferent surfaces with one texture, but i'll guess that flamingo can do this now.

[Rupes]

this does'nt get around the problem of having to split surfaces to apply multiple colours...

but a very effective approach in Rhino is to mesh (all) of your surfaces (using the detailed controls to get an efficient mesh that is visually approximate to the original surfaces), delete the original NURBS and save as a seperate file.

You can then use the mesh split tools (which are available in V4 & the V4 evaluation version) to split the meshes as per your colourscheme (as you do already with NURBS).

A model composed of efficient meshes will be much easier for Rhino to deal with; no NURBS data is stored, the filesize is reduced and you will notice much faster manipulation of complex models.

IMHO this is such a better way of working - render times go down and once your 'modelling' work is finished you can stop working on that file, and play around with a meshed version wich is much more suited to the rendering process.

It is still a pain to have to split anything, but if you think about the way NURBS work, assigning a variety of materials to different parts of a single surface would be quite difficult to control; and being able to split surfaces in the wide variety of ways you can within Rhino does give you a lot of freedom.

R

[Tim B]

ummm.... no, NURBS requires far less data to specify a surface than a triangle mesh does.

Think of a half-hull with 40 control points and compare it to a triangle mesh of 7000 points to APPROXIMATE the NURBS surface.

Tim B.

[Rupes]

Hi Tim,

I stand corrected if that's the case - however - this does reduce rendering times and filesize in Rhino (dramatically).

I really thought I understood this - obviously not, can you explain this behaviour at all?

Furthermore: All you ever see in rhino is a visual approximation to the NURBS i.e. the render mesh. The approach of meshing each surface individually allows you to apply custom mesh settings to each object (rather than using the 'global' render mesh settings; this results in much greater net efficiency in the model.

Very interested to hear your take on this - the effect is real.

[Rupes]

sorry think I just answered my own question - the benefit of the technique is obviously being able to control the meshing of individual objects? hence leading to greater mesh efficiency?

I get what your saying about NURBS and the amount of data - the point is that Rhino always reverts to meshes to solve the rendering calaculations - with a NURBS model it takes the global settings, if you mesh surfaces individually then those meshes are used in the rendering process?



R

Edit: try saving any amount of geometry in Rhino as nurbs, then convert all to mesh and compare file size - nurbs always much bigger

[snakefeet]

I would slightly offset the surface outboard (keeping the original surface) and trim the offset surface as needed to get a surface suitable for a different color.

For example, to color a hull bottom separately from the hullsides I would offset the hull maybe 2mm or a 1/16th of an inch outboard, trim the new surface at the waterline, give it a good bottom paint color and start rendering.

You can make any number of paint offsets and try every bottom paint color and every boot stripe & cove stripe shape you can think of, yet leave the the surfaces that make up the actual boat completely untouched.

[Tim B]

When you come to render (in any rendering software), you need to discretise the surface so that you can determine lighting effects, colour etc. This can either be done by a structured (rectangular) method, or an unstructured (triangular) method.

Obviously, if you manipulate a mesh directly it will be quicker than manipulating the NURBS surface and the mesh together. I would totally agree that each surface needs to have individual meshing settings.

Tim B.

[Tim B]

Further, have a llok on the POV-RAY site for more info on rendering.

www.povray.org

Tim B.

[Rupes]

Hi Tim,

Thanks for the link. Im familiar with POV-RAY and other rendering engines; I currently use Rhino & Flamingo (and soon V-Ray for Rhino) professionally for marine design and visualisation.

My original post was targeted specifically at Rhino use - are you familiar with the program? Tthe technique works 100%. I have a model of a 40m barge which is approx 400mb in Rhino as NURBS, it renders in, say, 12 hours in flamingo with basic lighting. The same model is around 27mb when converted as per my post, and renders with a lightdome of 30 lights in about 4 hours!

I can understand why there woud be less data required to describe a NURBS surface than a polygon mesh. But in Rhino there is always a polygon mesh created with the NURBS if you use the shaded view or try to render (although this can be cleared from the file using _clearallmeshes or 'savesmall') all I was suggesting was that this technique minimises the size of the mesh objects (which are referenced in the rendering process) and eliminates the NURBS (which are not used at all in the rendering process).


cheers R

[duluthboats]

snakefeet,
Thanks for the tip, I should have been doing that all along. I have been using new files.
Gary