Guidance - morphing between two surfaces

Hi All.

I have just started learning grasshopper and I find myself in need of 'steering' by someone who has some idea of what they are doing...

I am looking at using Rhino to draw the water table under the ground based on pressure monitoring data available over different dates.

In essence, I want to morph between two surfaces to show seasonal movements.

The picture below shows a hypothetical 'two surface' model - the red points in-between the two surfaces are where I have got to so far (the distance between surfaces is controlled by a slider):

Having got this far I was feeling quite proud for half a days work having never before used grasshopper ... HOWEVER - I am now stuck.

To get to this point I:

A) Divided each surface into 100x100 intervals.

B) Drew a line between each corresponding point in each surface.

C) Extracted a point from each line using a percentage of length (0-100% being from surface no. 1 to surface no. 2)

I have since tried:

1) Creating polylines with each row of data then lofting = failed

2) Creating a mesh from the points using a plugin = failed

3) Directly merging between the two surfaces using an algorithm put together by someone smarter than me (credit of this site) = failed because the number of vertices were different between the two surfaces.

I am really hoping someone can guide me on this as I am really at a loss about where to go from here.

Thanks in advance.

Lyndon J

Replies to This Discussion

Permalink Reply by Jeff C on February 24, 2015 at 9:10am

(sorry if any repeat posts, page errors required edits or delete&reposts)

Hello Dave,
sorry, i couldn't find a way to send a "message" rather than post, and wasn't sure you'd see my post to Lyndon whose understandably engaged.
I'm gradually finding own answers, but If your not likewise preoccupied perhaps you've moments for a couple questions if familiar with process,.

4) how to alter Lyndon's killer def. so it interpolates between Excel surface coordinates with different xyz points amounts and therefore "cell" amounts?,
..i assume both culling and data matching are required, but when time please mention any known requirements\procedures?

Lastly,

5) as seen in 3 screenshots, when using Untrim, sDivide then Patch Surface(as target)&Trimmed surface(as Source) within Copy Trim, the results are Rotated 90 degrees counter-clockwise around Z. Might you know how to correct this?

If i knew Rhino\GH so! powerful and fun, would've used them years ago.

Thanks D,
J

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Permalink Reply by Lyndon Johnson on February 24, 2015 at 4:09pm

Jeff,

What alot of posts!

Sorry I was not able to respond earlier - I was extremely busy with work.

I don't quite understand what you are trying to achieve with the interpolation when you are talking about different "cell" amounts.

Are you trying to interpolate between 1 set of, say, 30 points and one set of 25 points?

In terms of the rotation, if its rotated 90 degrees, just rotate it back 90 degrees using the "rotate" function in grasshopper, you set the object, angle and plane of rotation and you should be able to correct.

Cheers

Lyndon

Permalink Reply by Jeff C on February 26, 2015 at 1:56pm

Hi Lyndon,

Lol,.. i know, updates(so ya don't spend time on solved questions) and probably too much detail :)

"..different "cell" amounts..& ..to interpolate between..set of..30 points and..set of 25 points?.."
= when my 2 surfaces points(xyz coords) are written to XL i assumed the one with 30 points would take up more "cells"(longer columns) in XL than the set with 20. So yes, i am for example trying to interpolate between 2 sets of points one with 30+ points and one with 25+ points,.

"..just rotate it back 90 degrees using the "rotate" function.."
= tried that 1st, but although it rotated the Patch it did not correct or affect Copy Trims errored rotation,.

I'll prep and upload my def. if you like?,

Thanks for reply & suggestions,

Jeff

Permalink Reply by Lyndon Johnson on February 26, 2015 at 4:04pm

Hi Jeff.

Unfortunately my definition can only be used for 1 to 1 mapping of points - so you need to either cul some points - or generate additional points to run a 1 to 1. If you have different numbers of points you may need to go back to the surface generation, division technique to generate equal points.

I am sure it would be possible to automatically generate and match the extra points in grasshopper - but without spending considerable time to figure it out I'm afraid I cannot be much help.

You can upload your def, I will try and look at the rotation issue and see if I can find a fix for you.

Cheers

Lyndon

Permalink Reply by Jeff C on March 1, 2015 at 3:52pm

Thanks Lyndon,
great minds think alike; the sDivide, assign equal points blend is working sofar, and i'll return to cull/data-match dissimilar points counts in your Excel\interpolation script.

Also, i found a RevSrf component that swaps either or both UV's, but then found reverse_swap_UV.gh with a VB component which additionally inverts both uv's which worked correctly aligning my CopyTrim uv's with its surface. But since the Patch surface is larger than SrfGrid surface the CopyTrim surface is similarly distorted in size.
I'll upload the def. for any uv rotation fixes you've time for.

Your one def. taught me nearly all i needed or showed exactly what to look for. Thanks again for fasttracking me thru GH.
Big fan, Jeff