Closest point as a mean to find open space

I have been using grasshopper for 3 days now and I am trying to create a script that will find the largest and (hopefully) the best spaces to intervene in a very large city.

The approach I am using is finding the closest point from a building (internal element) to the street (external element). The subdivision and overlapping of these distances gives a graphic representation of which spaces are more susceptible to an intervention.

However I just hit a wall since I still don't grasp fully the concept and notions of trees and data in grasshopper.

the next step is to create a 2d polysurface (and someday 3D) with the points that conform the closest point lines. I need to sum 450 end point with 450 beginning points to generate 900 points. But using the math sum operator gives me the sum of the XYZ coordinate of the points.

After I solve this issue I will get to finding a way to replace the closest points that go inside a building with the second closest point. But for now, finding how to sum points and creating the surface is more than enough.

Attachments:

closest-point-for-plan-analysis.3dm, 129 KB
closest-point-for-plan-analysis.ghx, 112 KB
closest-point.jpg, 147 KB

Replies to This Discussion

Permalink Reply by Diego G on June 5, 2011 at 8:21pm

I found out that you can use a panel with shift to sum values...

Permalink Reply by David Rutten on June 6, 2011 at 2:09am

Hi Diego,

I wrote a small example that shows how to find empty circles inside your plan. The basic idea is you create a delaunay mesh (whose triangles are defined as those with empty circumcircles), then recreate the circumcircles for all the triangles in the mesh and finally remove all those circles you don't want.

I remove three sets of circles from the complete collection:

Circles that have their centre point outside of the plan boundary
Circles that have their centre point inside any of the building outlines
Circles that have a radius smaller than X

My solution for step 2 is very slow and you may want to re-order the logic so you first remove all the small circles as this is very fast and will vastly reduce the data-set.

I sympathise this may be quite a daunting example for someone who's 3 days into using Grasshopper, feel free to ask any questions about this file.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by David Rutten on June 6, 2011 at 2:10am

Attachments, attachments, attachments...

David Rutten

david@mcneel.com

Poprad, Slovakia

Attachments:

closestpointforplananalysis.3dm, 130 KB
find-empty-areas.ghx, 272 KB

Permalink Reply by David Rutten on June 6, 2011 at 2:16am

Here's another one that only limits the distance search around the boundary.

David Rutten

david@mcneel.com

Poprad, Slovakia

Attachments:

find-empty-areas-around edges.ghx, 94 KB

Permalink Reply by Diego G on June 12, 2011 at 10:49am

Wow David

I cannot thank you enough. I had been playing with circle packing before writing my own script, and thought it was not the right approach...

Im sorry for replying so late. At the start of the week I tested your script on my file and must had done something wrong because it didn't seem to work at that time, most probably due to testing it in my own 3ds file and messing the input, which I got right now after downloading both files you posted.

Since my week tend to be quite busy I decided to wait for my "free day" (Sunday) to try to understand your script (which I still want to do) and make it work (which is no longer necessary :) ).

My next step is to do a few more tests with different street blocks. And then find ways to do this aproach to about 300 street blocks more. What kind of tool would you use in grasshopper to create such a database (so I can get to whaacht the related videos and tutorials ).

I will keep posting my improvements. And questions that seem impossible to answer.

Here is an image of the city that will get into grasshopper.

Again thank you, and I am going to play with your script to understand how it works.

Permalink Reply by Diego G on June 12, 2011 at 11:13am

Attachments!

Attachments:

land-usage-120611.jpg, 1.4 MB

Permalink Reply by Diego G on June 12, 2011 at 10:53am

Seems like a dumb question but how do you add and attachment no a reply?

Permalink Reply by Danny Boyes on June 12, 2011 at 11:07am

below the window that you write the reply in there is a link to upload files. Once Clicked you get the option to attach up to three files

Permalink Reply by Diego G on June 12, 2011 at 11:12am

Thank you Danny:

I just found out that there are compatiblity issues between the site and the opera browser and the built in spam blocker.

Permalink Reply by maxmelone on January 27, 2013 at 9:27am

Hi,
I just used your find-empty-areas.ghx, and it works great! After 1.5 years it still helps me a lot.
But does anybody know if there is smarter way meanwhile?

It works perfectly, but as David said, it is really slow...
greetings,
--
max

Permalink Reply by Daniel Piker on January 27, 2013 at 9:51am

Maybe try looking at the Medial Axis Transform
The point on the medial axis with the largest radius function will be the furthest from your sites

Permalink Reply by maxmelone on January 27, 2013 at 1:15pm

Thanks Daniel!
I was already thinking about that definition before - I saw it at one of your posts, but just didn't use them... don't know why. But now I did and thats the Frankenstein I built:I used one boundary curve and 2 "islands", with which I referenced the definition with. Didn't tried it with different/ more curves until now, but I will. So I still didn't test if its much faster, but I am quiet sure it is.

Attachments: