image sampler

hi.

i am trying modify a surface with an image sampler.

is it possible to get control points of a surface in grasshopper?

my idea is to modify height of some points that would come from an image sampler

the thing is i modelled a city, with topographic data from gis program, but the river is not fine. so i wanted to take the image of the river from photoshop, and modify the surface with it.

would work?

other way?

thanks

pd.well, i saw the _heightfield command...this is what i need but on a 3d surface, and better if i could control the vector direction...
:)
ideas?

Replies to This Discussion

Permalink Reply by javier zaratiegui on March 8, 2010 at 9:40am

well, i saw the _heightfield command...this is what i need but on a 3d surface, and better if i could control the vector direction...
:)
ideas?

Permalink Reply by Suryansh Chandra on March 8, 2010 at 11:56am

The heightfield command is quite easy to recreate in GH, all you need is to sample the image on a grid of points, and use either of the Color channels (or a cumulative value) to move around a bunch of points that make the surface. You could either get the surface CVs using the OnNurbsSurface.GetCV method through code, or make a grid of points, move them, and use the [Surface from Points] component to make the surface.

The problem usually is that the points will always be on an orthogonal grid, and the image will also we always sampled on an orthogonal grid. For organic topology to show up (which I am assuming is the case with your river), you will need a pretty good resolution of image sampling, and correspondingly a very high number of points making your surface.

I would try to find a way to align the isocurves of the surface with the topology of the river, which can help you get a good surface with fairly lower point counts. In other words, I would try and create a surface by lofting curves that trace the topography of the river.

Permalink Reply by javier zaratiegui on March 9, 2010 at 2:02am

so, i have seen a distort script, that maybe could use instead of the image of the river...but i really want to use the image. maybe is not the right time, as you said, i will need many points...
but i like to get used to new buttons...and hadn't played much with image sample.
thanks for the help, really

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