How to draw splines between two other?

[Anonymous]

Hi!

My problem is too hard for me to cope with in this little time I have, so I hope somebody knows the answer for this and can help me:

I have two splines on a map representing the height of the area above sea level. Let them be for example the line of +10,00 m and the other one is that of +20,00 m. They are weaving all around 🙂 How can I draw the splines of the -for example- +12,00 , +14,00 ....+18,00 m height knowing that these splines must divide the distance between the two main splines equally?
I attached a drawing hoping it helps a bit if it was confusing.

Thx in avdance 🙂

[devitg]

Please upload it as a true DWG , or send it off line to my e mail .



see attached file

[Anonymous]

Thank you, I wrote an email to you 🙂

[stevor]

The method we used to generate intermediate lines for topo and like maps was to:

...generate many point locations [coordinates] along each source line, or Spline;

...match them to the neastest ones on the next source line;

...generate coords for the mid points of the matched pair;

...and make a new line from that sequence.

Other geometries can be done with the matched pairs, like 4 or 5 or 10, pseudo-parallel intermediate lines.

It is the same as using interpolation to get an elevation between topo lines.

Many other aspects can be programmed in, for more automation.

[Anonymous]

What you are speaking of are elevation contours. And it appears you wish to
add contours at intermediate elevations programmatically via interpolation.
Most Civil packages treat contours as 2D polylines, though Land Desktop and
Civil3D create custom objects based on 2D polylines. The use of splines may
be convenient for people tracing contours, but are somewhat troublesome to
deal with programmatically because the knots are not actually on the path of
the spline, and the terrain can have sumps, crests, saddles, swales, and
ridges that usually need human decisions to interpret and represent
correctly.

If you were looking for assistance in writing your own solution, I and
others would be glad to help. Please correct me if I'm wrong, but it seems
you may be looking for freeware to create the intermediate contours. There
are some in this forum who enjoy donating their time to create such valuable
solutions, but I think you should either learn to create program solutions
yourself, in which case we can help, or buy into a package that can create a
digital terrain model and create contours at whatever elevation interval you
desire.

Your best and quickest solution in the meantime is to draw the intermediate
contours by eye.

--
John Uhden, Cadlantic

http://www.cadlantic.com
Sea Girt, NJ

wrote in message news:6096574@discussion.autodesk.com...
Hi! My problem is too hard for me to cope with in this little time I have,
so I hope somebody knows the answer for this and can help me: I have two
splines on a map representing the height of the area above sea level. Let
them be for example the line of +10,00 m and the other one is that of +20,00
m. They are weaving all around 🙂 How can I draw the splines of the -for
example- +12,00 , +14,00 ....+18,00 m height knowing that these splines must
divide the distance between the two main splines equally? I attached a
drawing hoping it helps a bit if it was confusing. Thx in avdance 🙂

[Anonymous]

Hi,

To add to John's comments.

The marginal cost of Civil 3D over AutoCAD is about $2500. (Check with
your dealer for the actual value - it varies with country amongst other
things)

Add the cost of learning to create DTMs and display the contours - say a
day.

The time to create contours at any required interval, or to get
predicted levels at any point for a whole drawing with Civil 3D would be
about a couple of minutes - i.e. trivial

Compare the cost of your time to create a suitable program or to hand
draw the contours as John suggested over a period of time.

If you have to do this lots of times, even without taking advantage of
other Civil 3D enhancements over AutoCAD I think you'll find Civil 3D a
good investment.


Regards


Laurie Comerford


John Uhden wrote:
> What you are speaking of are elevation contours. And it appears you wish to
> add contours at intermediate elevations programmatically via interpolation.
> Most Civil packages treat contours as 2D polylines, though Land Desktop and
> Civil3D create custom objects based on 2D polylines. The use of splines may
> be convenient for people tracing contours, but are somewhat troublesome to
> deal with programmatically because the knots are not actually on the path of
> the spline, and the terrain can have sumps, crests, saddles, swales, and
> ridges that usually need human decisions to interpret and represent
> correctly.
>
> If you were looking for assistance in writing your own solution, I and
> others would be glad to help. Please correct me if I'm wrong, but it seems
> you may be looking for freeware to create the intermediate contours. There
> are some in this forum who enjoy donating their time to create such valuable
> solutions, but I think you should either learn to create program solutions
> yourself, in which case we can help, or buy into a package that can create a
> digital terrain model and create contours at whatever elevation interval you
> desire.
>
> Your best and quickest solution in the meantime is to draw the intermediate
> contours by eye.
>

[Anonymous]

Hello 🙂

Thank you all for the valuable pieces of advice. The truth is I was trying to create a routine that would draw the intermediate terrain contours, but as I am in lack of time, I thought some of you had already met this problem and solved. It hadn't even crossed my mind to invest a program, I agree that it's more worth to learn how to write my own 🙂
After all, I am through with this, I drew them manually, but in the meantime "along the road there were many beautyful flowers worth to smell":)

[stevor]

To do this automatically is a big program, which is why you get offers to do it for you.

We did it, with a kludge of code that probably would not fit your job or even run there, plus that code is someone's property now.

If you search more subjectively than just asking, you may find stuff.

One strong possibility, a slightly newer solution, but may help you:

CONTOURS.LSP by Tony Hotchkiss

http://aec.cadalyst.com/aec/article/articleDetail.jsp?id=180709

There is, or was, a plethora of brilliant code written in autolisp.