Re: octaviz and color

[alberto_gh]

Hi,

Could you be more specific in how to assign scalar inputs and modifying a
color scheme please? I have tried to plot only one triangle at each time
with one color based in my curvature value at each of that triangle's peaks
but I don't get a good result. Is there any way to do it as if it was a 4d
plot, where the fourth dimension, represented as a color, takes values from
a vector?

Thanks very much

Alberto

Jonathan Stickel wrote:
> 
> I would have responded sooner, but I have been away at a conference ...
> 
> Jeff Abrahamson wrote:
>> I've been playing with octaviz all morning.  It's very nice.  My need
>> is to image surfaces for which I have triangular meshes, so I find
>> myself using vtk_trisurf mostly.
>> 
>> Near as I can tell, though, vtk_trisurf.m ignores anything I say about
>> color.  Am I confused?
> 
> There are currently two ways to give color information to vtk_surf and 
> vtk_trisurf: either a set of scalars corresponding to the individual 
> points, or an [R,G,B] vector defining a single color for the entire 
> plot.  For the former, the scalars are mapped through a color scheme to 
> produce the final color of the surface.  In Octaviz CVS there is now a 
> function to change the color mapping (vtk_colormap).
> 
>> 
>> What I want to be able to do is color certain triangles special
>> colors, such as have a triangulated shape that is all light gray but a
>> few regions I'll want to highlight in blue and a few others I'll want
>> to highlight in red.
>> 
>> As a toy example, suppose I want to discover regions of high
>> curvature.  I'd then want to highlight triangles adjacent to high
>> curvature areas so I can see how well my curvature program works.
>> 
> 
> Assigning scalar inputs and a color scheme may be sufficient for you. 
> Assign high scalar values to points of high curvature and low scalar 
> values elsewhere.  Then choose a color scheme that you like (from 
> octave-forge functions).  You could also define your own colormap.
> 
> It is possible to use low level vtk programming to assign individual 
> points (or triangles) certain colors, but for that you will need to 
> learn VTK.  I think you will get what you want quicker by using the 
> available scripts.
> 
> Jonathan
> 
> 
> 
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