Visualizing Changes in Topography (Historic vs Current contours)

Hi All--

I don't even know how to approach this problem...

I have a set of historic contour lines and a set of current contours line for a site I'm working with in Rhino. (historic contours in one layer, current controls in another layer...I can separate the contours out into individual layer)

I'm trying to visualize the changes in landscape (excavation, cut/fill) from 1928 to current. Some historic contour lines remain the same as today. However, most have been wildly altered.

My vision is to produce a "Heat Map" like visual, where contours that have been radically changed will be assign a color. Eventually, once all contours are evaluated, the overlays will produce a gradient.

eg. I have historic contour 973 ft. I see that current contour 973 ft starts off following the historic contour but then changes path but eventually merges back to the historic contour. The area of difference is what will be highlighted.

Any tips? Insight?

Thanks!

Replies to This Discussion

Permalink Reply by David Rutten on February 4, 2016 at 11:44am

Do the contour lines have correct height, or are they named or something?

If they are in the correct 3D location, I'd use Delaunay mesh or maybe Path to generate the two landscapes, then shoot rays up from the zero-level and figure out where they intersect the historic and present landscapes. The difference in intersection height can be mapped onto a gradient.

Any chance you can upload some of those contours?

Permalink Reply by Danny Le on February 4, 2016 at 2:58pm

Thanks for getting back.

Here's the Rhino & Grasshopper script we're playing with...

Current topo is in layer 3D-TOPO 2-GIS and have correct height in Z.

Historic topo is still flat. They're in layer HistoricContour.

The current script is just evaluating the displacement of two curves and visualizing the length of displacement with a gradient....HOWEVER, if we do this for every elevation, it might look a little messy.

Let me know what you think.

Permalink Reply by David Rutten on February 4, 2016 at 3:13pm

No attachments here. Note that there's a 5MB limit on uploads.

Permalink Reply by David Rutten on February 4, 2016 at 3:44pm

Here's my suggestion worked out. I import two surfaces, contour them up in GH, then reconstitute the landscapes as meshes, and finally I sample the elevations and map those differences to a gradient.

Attachments:

landscapes.3dm, 363 KB
landscapes.gh, 13 KB

Permalink Reply by Danny Le on February 4, 2016 at 3:55pm

Hi David--

Thanks! Here's what we were working with...def not as good as what you came up with.

Attachments:

topo_3.3dm, 177 KB
topo_script.gh, 14 KB

Permalink Reply by Joseph Oster on February 4, 2016 at 5:58pm

Not a reply to your quest, just idle play with one set of your contour lines. Both sets are internalized so no need for Rhino file.

Loft between the contours doesn't work quite right but looks sort of terrain-like at times.

Attachments:

topo_script_2016_Feb04a.gh, 31 KB

Permalink Reply by Danny Le on February 14, 2016 at 8:40pm

David--

Thanks for the tip. After some more research, we came up with this. Let me know what you think. You see anyway of optimizing it?

Attachments:

meshdisplacement_colormapping.gh, 14 KB

Permalink Reply by Jeg on February 4, 2016 at 5:30pm

Danny,

David's suggestion is a v. sensible approach. I think it's effectively an Isochore analysis between historic and contemporary landscapes heights. Might be worth googling that (or Isopach) if you want to understand other ways they are used/analysed in landscape design. ~Jeg

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