# Terrain elevation lines

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Does CA use bezier curves to interpolate between elevation lines?

I am trying to create sloping terrain using only elevation lines.

If I wanted a flat region under a house (such that the terrain is at the same level for all doors), I draw one elevation line at the far left of the house and set it to 0.

Then I draw another at the other extent of the house and set to 0. So far so good.

Then for my walk in garage, even further right I drawn another line 1' away from the previous line and set it to -120".

CA's response is to create a HUGE bump of terrain between where I specified it be 0.

I can think of a much easier use of elevation lines.

How about you set elevation line heights and they remain the same no matter what height of subsequent elevation lines.

Is this an extreme request?

If I were developing software, the curve between the two 0s would be converted into a straight line. Then from the right end of the straight line to the -120 it should pop in a sharp decent to the -120 with options for a rounded corner.

Can someone show me how to make the following...

1 rectangular flat terrain of height 0 and dimensions 30' W by 60' L., dropping to -120" in the distance of 1' from the end of the terrain(using only elevation lines)?\

Thanks to any who attempt this.

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A good question. I have no idea how elevation lines are designed to work in Chief but certainly not in a way that works within the logic of my mind. That's why I never use them, never understood them, and always use elevation regions instead.

Here's what I get when setting your defined scenario. Someone, somewhere probably understands why a zero elevation line doesn't remain a zero elevation line, most likely the brilliant (and I am NOT being sarcastic) software engineers at Chief but unfortunately I am not a software engineer so the logic simply escapes me.

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For me, it's a crap shoot. Sometimes I win and sometimes I say "Fuggetaboudit!" I used to avoid the terrain tool entirely and uses Flat, Graduated Slabs (make the material grass) similar to the Old Cardboard Topo models we made in Architecture School. I have had some luck reading and re-reading the tutorial and going online and occasionally finding things from ChiefTalk but still haven't found the Magic Handshake for the Terrain Logic.

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Straight line interpolation might be an option, but if it were the only option, it'd cause more problems for modeling than it would solve. Chief's tools will do exactly what you need but it does take a fair bit of practice to understand them. In my region, we need to plot the geodetic data for every residential lot (in an urban setting) using predetermined elevations set by the civil engineers who have designed the drainage patterns for the sub-division. The interiors of the lot also must be graded using a set criteria determined by the municipality to maintain appropriate drainage characteristics. Chief handles all of this wonderfully...if you're well versed in how the terrain tools work. That being said, I have made a suggestion for a straight-line interpolation tool using an elevation line where you could set the height at each end and Chief would model it straight in between.

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+1

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Try using terrain regions instead of terrain lines... see if that helps you.

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1 hour ago, parkwest said:

Try using terrain regions instead of terrain lines... see if that helps you.

Yes elevation regions as suggested above are much more cooperative.

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Elevation Regions are nothing more than a series of elevation lines that have been closed (i.e. a closed elevation polyline).  Once closed though, you get a couple extra options, one of which is to set the interior to be flat.

For the desired end result in the OP, an elevation region set to have a flat interior is the most logical choice (and what I would personally use), but a person could also either add a series of

additional 0” elevation lines to keep the automated smoothing in check, OR set the smoothing to linear.  The latter may cause problems elsewhere on the terrain though if you needed the automated smoothing for other areas.

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36 minutes ago, HumbleChief said:

Yes elevation regions as suggested above are much more cooperative.

Brilliant video Larry. Thanks for that simple demo.-BB

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Re setting the interior to be flat...where is that option? I tried selecting one of the two elevation lines and opening the object to see if there is a 'flat' switch. None. I thought, well, how can CA know what to make flat unless I specify both lines 1 AND 2. So I did and did open object again. Also no flat switch. Is this a default setting so ALL elevation lines are be set to flat between all subsequent lines?That would seem limiting. I would think it would be better to be able to pick any two elevation lines and open object and find a flat selection box.

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2 hours ago, HumbleChief said:

Yes elevation regions as suggested above are much more cooperative.﻿

Thanks for the video! Alaskan_son says there is a flat switch to set between two elevation lines. That should probably be the default unless you can also specify any alternative.

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8 minutes ago, rockyshepheard said:

Thanks for the video! Alaskan_son says there is a flat switch to set between two elevation lines.

That’s actually NOT what he said. Re-read that post.

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So I got it figured out.

You don't need to find flat switch.

It appears you need to make three lines at 0.

The first line should be at the very left edge. The first two lines then define the flat plane. The third line at 0 prevents CA from interpolating the first two lines, thus leaving it flat.

Then a fourth line at the right edge of the terrain so that CA interpolates a curve between the 3rd 0 and the fourth line...in this case -120.

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3 hours ago, rockyshepheard said:

Alaskan_son says there is a flat switch to set between two elevation lines.

No he didn't .....

Elevation Regions are nothing more than a series of elevation lines that have been closed (i.e. a closed elevation polyline).  Once closed though, you get a couple extra options, one of which is to set the interior to be flat.

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2 minutes ago, Kbird1 said:

No he didn't .....﻿

This was what I meant that he said.  "Once closed though, you get a couple extra options, one of which is to set the interior to be flat." An option, a switch. Same thing right? ﻿

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14 hours ago, rockyshepheard said:

This was what I meant that he said.  "Once closed though, you get a couple extra options, one of which is to set the interior to be flat." An option, a switch. Same thing right? ﻿

Yes I knew what you were referencing but Michael was talking about Elevation Regions NOT Elevation Lines .

this may help you understand the 3 line (point) concept and how it works....to a point.... think of the Terrain like a big Waterbed ...push down in one area , it will popup in another in this scenario.....

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I once heard someone from Chief describe their terrain modeling like working with cellophane.  Then I went to the kitchen and tried to make a terrain model with cellophane - and realized.....he's right, Chief's terrain models are just like that.

...followed by the thought - why would someone make a terrain modeling process similar to working with cellophane?

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Johnny,

I agree that comparison just doesn't make sense.

The terrain cannot be compared to a statically sized surface or piece of material like a sheet (or Cellophane).

The terrain needs to be compared to a surface that can stretch and contract like a sheet of rubber.

It would be impossible to create a terrain (other than flat) if the terrain surface could not expand and contract.

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14 hours ago, Kbird1 said:

Yes I knew what you were referencing but Michael was talking about Elevation Regions NOT Elevation Lines .

this may help you understand the 3 line concept and how it works....to a point.... think of the Terrain like a big Waterbed ...push down in one area , it will popup in another in this scenario.....

Thanks Mick, I knew there was an explanation even I could understand...

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19 hours ago, rockyshepheard said:

It appears you need to make three lines at 0. (This is the Key to avoiding that annoying interpolated arch as Rockney states)

The first line should be at the very left edge. The first two lines then define the flat plane. The third line at 0 prevents CA from interpolating the first two lines, thus leaving it flat.

Then a fourth line at the right edge of the terrain so that CA interpolates a curve between the 3rd 0 and the fourth line...in this case -120.

...and there's the "Secret Handshake" that I had once found and then forgot. Thanks for the Refresher. BB

Edited by Archnot-Boltz
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7 minutes ago, HumbleChief said:

Thanks Mick, I knew there was an explanation even I could understand...

Terrain is a bear (specifically a Grizzly) to say the least , I certainly need to speed some more time reviewing Chief Videos etc ...again....

Terrain Regions certainly make it easier if you have areas all of the same Elevation...

M.

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2 minutes ago, Kbird1 said:

Terrain is a bear (specifically a Grizzly) to say the least , I certainly need to speed some more time reviewing Chief Videos etc ...again....

Terrain Regions certainly make it easier if you have areas all of the same Elevation...

M.

You might be amazed by what a good heavy equipment operator can do with the terrain.

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5 minutes ago, Kbird1 said:

Terrain is a bear (specifically a Grizzly) to say the least , I certainly need to speed some more time reviewing Chief Videos etc ...again....

Terrain Regions certainly make it easier if you have areas all of the same Elevation...

M.

Elevation regions are really very, very flexible for every elevation challenge.

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14 minutes ago, parkwest said:

You might be amazed by what a good heavy equipment operator can do with the terrain.

If only the City would accept a Note on the Plans saying "Don't worry the Excavator Operator will handle the Terrain"

M.