Creating topography surface to export .STL file from XYZ .csv?

Hello All,

I am very new to Grasshopper and have traditionally used QGIS for creating topography but am trying to do it in Rhino. I have a list of xyz points in a .csv attached. I would like to interpolate a smooth surface based on these points. Any suggestions are greatly appreciated. I have tried the Delaunay Mesh but now need to smooth it and create a file in Rhino that can be exported as a .stl.

Thank you,

Anya

Attachments:

xyz_MealGapCUS.csv, 79 KB

Replies to This Discussion

Permalink Reply by Joseph Oster on November 15, 2017 at 12:34pm

Looks more like a cloud of points than a surface? Are X, Y and Z mixed up? (not that that would help)

Permalink Reply by Anya A'Hearn on November 15, 2017 at 12:40pm

Thank you, Joseph, for your quick reply. The points are centroids for each county in the continental US. If you look at it from the top you will see the US. In QGIS I would use Grid Interpolation using an Inverse distance to a power algorithm to create the topography.

Permalink Reply by Joseph Oster on November 15, 2017 at 12:44pm

Ah, yes... missed that. Looks a little distorted?

Might want to 'ReMap' the Z values to something less extreme? Oh, is that what this means?

an Inverse distance to a power algorithm

P.S. Just saw this yesterday - depends on a boundary curve though:

http://www.grasshopper3d.com/forum/topics/delaunay-triangulation-in...

Permalink Reply by Anya A'Hearn on November 15, 2017 at 1:36pm

Hello Joseph,

The Z is a metric - in this case missing meals per year / 100,000 per county (as opposed to using elevation) to create an alternate topography of the US. so the Z should look very off. :-). With the drape in Rhino, it actually looked pretty interesting as below. Still,I am looking for a way to interpolate the surface and be able to export it as a .stl file.

Anya

Permalink Reply by Joseph Oster on November 15, 2017 at 2:53pm

I'm not a "mesh guy", just hacking here... Trying to trim out the extraneous faces/edges. Just as I was about to post this, I realized that my filtering effort would be more effective and stable (not influenced by height scaling) if I project the mesh face boundaries to a plane before measuring them. I'll try that next.

This one was "done" so I'll post it anyway.

Attachments:

county_topo_2017Nov15a.gh, 23 KB

Permalink Reply by Joseph Oster on November 15, 2017 at 3:22pm

I realized that my filtering effort would be more effective and stable (not influenced by height scaling) if I project the mesh face boundaries to a plane before measuring them.

That was easy and much more effective. Still not a perfect "convex trim", maybe one of the mesh experts here can do that better?

Then I decided to throw in this bit from a thread ~2 weeks ago, to make it a "solid":

http://www.grasshopper3d.com/forum/topics/expand-extrude-a-mesh-and...

Attachments:

county_topo_2017Nov15b.gh, 33 KB

Permalink Reply by Anya A'Hearn on November 15, 2017 at 4:07pm

Very cool! Thank you so much for your help!

Do you have a twitter handle so I can thank you when I post the visual result?

Anya

Permalink Reply by Joseph Oster on November 15, 2017 at 4:46pm

Nope, thanks anyway. It could be better. You're welcome.

Why does it look stretched East <--> West?

Permalink Reply by Anya A'Hearn on November 15, 2017 at 4:51pm

I believe it got stretched when the projection changed to a flat earth.

Thank you again! I am having fun digging in and figuring out each step.

Anya

Permalink Reply by Joseph Oster on November 15, 2017 at 5:19pm

Why does it look stretched East <--> West?

I used a trimmed copy of this image to determine a 'W/H ratio' and used that to compute a scale X factor for the field of points.

https://wall.alphacoders.com/big.php?i=687665

Looks a little more as expected, but these points are county seats(?) and don't define any real perimeter curve, so it's still approximate. You can plug a 0..1 slider into the 'Scale NU (X)' input instead of the 'BBox/Edges' calculation.

Viewed from high above Canada:

Attachments:

county_topo_2017Nov15c.gh, 41 KB

Permalink Reply by Joseph Oster on November 15, 2017 at 6:15pm

This is the outline of that same map image, superimposed on the mesh (Rhino 'PictureFrame'). Still not a great match.

Permalink Reply by Anya A'Hearn on November 15, 2017 at 6:24pm

Thanks! To start, I created a centroid of each of the county shapes and used that as the XY. That would be why the outline is not the same as if I just used the county shapes. I will play with the projection conversions to get a slightly better fit if possible. Again, thank you! I really appreciate your help and realize there is a lot of learning ahead, as well as really exciting applications!