MoI for modeling of terrains

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 From:  d^^b (DAVID)
3551.1 
Hello:

I must to do a job (actually, this will be the first time I use MoI for a commercial use), and I have to start modeling the terrain for fit the development over there.

I want to share my strategy for do it, and ask to the forum if you know a better way to do it, and other doubts.

- First at all, I exported the AutoCAD curves to pdf using "Solid Converter", and then I imported the pdf file. The results was very good
- The second step was very tedious, because I must to join any curves and add lines on the places where the number of the elevation broken the curve.
- Then, I rebuilt all the curves, looking for erasing a lot of control points. Curiously, the file after that was bigger than the original one. :-?
- Then, and following the original plane (each 5 meter there was a curve with the elevation) I changed the Styles, making easiest the reading of the curves
- Now, the other tedious step, because I must to change the height to the curves, one by one. I wonder if could be posible any script of similar, for define the height of the each style, and change it autamatically when I change the style of the curve.

-And when everything is ready, the doubts starts.

My idea is to use the Loft command for join the curves and create the surface.
The better result I´ve obtained is using Loose and # points. I get a smoothed surface and the computer works fine (in Auto it doesn´t work)

Anyway I think that wold be a better method if I extrude the curves getting a terrraced terrain. In this way, I had "steps", but I got a solid mesh.

Another question: any tips for made the surface between any curves who form a "Y" profile? (see the lat picture)

I put any pictures for ilustrate it:
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 From:  Michael Gibson
3551.2 In reply to 3551.1 
Hi David, another possibility would be a "heightfield" approach where you have the terrain as a bitmap image with different brightness pixels for different elevations.

Then you can use something like ZSurf to build a surface based off of that bitmap.

See these links for some discussion on ZSurf and a download link for it:

http://moi3d.com/forum/index.php?webtag=MOI&msg=602.7
http://moi3d.com/forum/index.php?webtag=MOI&msg=2799.8
http://moi3d.com/forum/index.php?webtag=MOI&msg=2640.1


But it looks like you have some fairly steep slopes there, that may be more difficult to do with ZSurf.


Another thing that can work for this kind of stuff is the Patch command in Rhino, which can fit a surface through a set of contour lines. It may also be difficult to do things with steep slopes in it, but if you have Rhino available that could be something to try.


> Another question: any tips for made the surface between
> any curves who form a "Y" profile? (see the lat picture)

That's the kind of difficulties that you'll run into trying to use Loft for something like this that may have branching or separating profiles.

Instead of lofting, you could solve this by doing a different style of terraces by having each level only extruded straight instead of directly lofted between them. (which I see you mentioned - that solves this kind of problem though)

See here for an example:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2321.1

Also I think that Pilou has a link in that thread there with some information on a terrain tool for SketchUp, that could possibly help you out for this task.

- Michael
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 From:  Michael Gibson
3551.3 In reply to 3551.1 
Also I think Form-Z has some tools for making terrains from contour lines, that is another possibility.

It's somewhat easier for a polygon mesh based approach to be used for terrains, since the irregularity of the contour lines does not tend to lend itself very well to the regular control point grid structure that a NURBS surface is based on.


You might also search for tools that deal with a "Triangulated Irregular Network", or TIN:
http://en.wikipedia.org/wiki/Triangulated_irregular_network

- Michael
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 From:  Frenchy Pilou (PILOU)
3551.4 In reply to 3551.3 
< "Triangulated Irregular Network", or TIN:
That is the ne name of the result of the inside Sketchup Tool "SandBox" / Make by contour = Tin surface ;)

2 very good tutorial video (just wait seconds to start loading it's QuickTime )
http://go-2-school.com/media/view/41 use of the SandBox
http://go-2-school.com/media/view/37 for 4 methods of building terrain with the sandbox

and if you will use Sketchup and import cadastral's files don't forget to use the plug "Simplify contour"
the last of the page
http://sketchup.google.com/intl/en/download/rubyscripts.html

EDITED: 20 May 2010 by PILOU

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 From:  d^^b (DAVID)
3551.5 
Hello again:

Thanks Michael and Pilou. I had forgotten the thread you told about.
Actually, the Pilou´s method in Sketchup has been very very quickly and easy. (well, not easy for my computer, who spent almost an hour for draw the surface). The problem is that I can´t manage this file, because is so big and complex that it crashed always I´ve tried to export the file.

I have tried to export it with the Sketchup 7 pro EVAL -I have trying during the 8 hours for evaluate...what a pressure :-) - but nothing. Always crashed.

The other option is to start and finish this project in Sketchup, but I don´t feel comfortable with this software (it´s very easy but too new for me).

Well, I must to decide what are the best steps to attack this project.

P.S. :The option to extrude the curves can be the best. I didn´t want to make that because this obligate to me to close all the curves, but I have spent all the day probing options and surely in this hours all the curves could be closed and the volume finished :-)
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 From:  Michael Gibson
3551.6 In reply to 3551.5 
Hi David, you may need to try something like only do a small portion of the contours at a single time within SketchUp. Do some contours, save that result out and then delete it, etc...

Another possibility is to use Rhino with the Delaunay triangulation command from this plugin:
http://wiki.mcneel.com/labs/pointsetreconstruction

- Michael
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 From:  rabbit
3551.7 In reply to 3551.5 
This comes up continuously in the sketchup forum - ie the best way to do this. Below is some of the ideas that I have made notes on over the years - I think that this is a case where a mesh modeler is better than nurbs, but Michael's suggestion that you use rhino with the delaunay plugin is probably the best shot if you want to stay in nurbs.
Also, in your original post you mentioned exporting via something out of autocad as pdf, and importing that into moi - I don't think this is a good idea, as you will get heaps of little lines, whereas if you export as step or something it should be much cleaner, or use rhino which has very good dwg and dxf import...(you can download rhino and use it forever free, it just wont save your work after 25 saves - you can also just copy and paste through to moi, but only 25 times)
Anyway, for what its worth see below for ideas...you might also search the sketchucation forum for "terrain", "tin" and the like - there will be heaps of info there...
(just a note - you will see people talking about "ruby" or "rb" in conjunction with sketchup - these are plugins that people have coded to do various tasks - some of them are very elaborate, most of them are free...)

good luck

rabbit



I have an acad site plan and survey with topography of site. What is the simplest way to get this terrain accurately into sketchup, to enable me to place buildings on it.

---

- Do A Save as on the original acad file, Keep the original, original.
edit the new file and get rid of the stuff you wont be needing, like lot dimensions, notes, etc.
Open a fresh SU screen, select import, and select the file.
after it is in Su and saved, use Weld to connect the topo segments into each topo line, and while you are selecting those segments and get tired of missing the selection, the SelectionMemory2 ruby is right on.
After all your topo lines are welded, move them in the blue axes your intended distance.
after the topo is elevated use smoove to get the skin.
When you have site objects to transfer to the topo, leave them at work plane (flat) and project them up to the topo surface.
You can project the building from below or take the footprint above and stamp it to the surface.

---

- If the topo file is all choppy lines, etc. - I have had the most luck by the following steps;
1- deleting everything you don't need in the copy of the cadd file and flattening the contour lines
2- import file with just contour lines (x-ref ruby works nicely)
3- trace over contours using bezier spline ruby ( find it in the repository here)
4- delete cad file and edit the splines as you need to to simplify, etc.
5- move the splines to correct elevation
6- sandbox tools from here.

Seems like a lot of work if you already have the cad file with contours at specific elevations - but my experience has been that this is much cleaner and produces a better contour mesh. Install the rubies and give it a try on a little section. While I am proficient in cadd - I still find that the cleanup and work in sketchup to be much faster than "fixing" choppy or complicated contours in a cad file. Also - you have much more control over the level of detail, and can simplify where it is appropriate.

---

Note also that cloud.rb (or cloud_V6 for SU 6) also creates faces but from xyz data in text files. Just perfect with survey data (I use it a lot for reconstructing archaeological layers

---
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 From:  d^^b (DAVID)
3551.8 In reply to 3551.7 
Hi rabbit:

Very thank you for all.

Well. I had to post my impressions about Michael´s suggestion, but I am a bloody lazy :-)

In fact, I didn´t probe delaunay plugin because I read that it doesn´t generate a nurbs surface but a polygonal one.

My idea was to work over the surface drawing roads on it, defining levels for platforms where buildings were placed, and then I need to keep the nurbs surface for made operations like trim, use boolean commands and more....

Another thing. The model I showed was deformed, and the Z scale was multiply x 10, for aprreciate the reliefs, but it´s not a mountainous area.

Well, those were my initial ideas.

After read to you, I have the ideas more clearly, but I still have the problem that I get a not-nurbs surface. Well, the other idea is to model the buildings in MoI and export them to Su, but....I have a new problem, and it´s that at the end I couldn´t render the result.

Then, I prefer to model all of them in Rhino and export them to Blender. I don´t know....

Anyway, the method for export from AutoCAD to MoI to step is very useful to me.

Very thank you
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