Elevation Data Point Problem

[Griffin]

Help!  

 

I'm trying to enter surveyor data for a site plan and having issues with the elevation data points.   The lot is 850 feet above sea level.  A sample file is attached with a square terrain region and then four elevation data points with a few feet of elevation change.  I would need to add thousands of points or contours to get this to behave. Using terrain regions is not an option because I need contours that show the actual MSL data.

 

 

 

 

 

 

Elevation Data BUG.plan

[dshall]

You have one terrain and 3 elevation points.,.....  correct?

 

the elevation points are set at 855' plus/minus  correct?

 

If you select the terrain and set the SUBFLOOR HEIGHT ABOVE TERRAIN TO 855' ,  you get essentially a flat lot,  correct?

 

so start setting the SUBFLOOR HEIGHT ABOVE TERRAIN TO 855' to what you  want......  confusing?  yes,  but somehow we will muddle our way through it.

 

 

The point is all you need to do is to set SUBFLOOR HEIGHT ABOVE TERRAIN correctly and you should be good

 

Did that help?

 

[Griffin]

Thanks for the reply.  

 

I'm not even getting that far.  If you look at the file I uploaded  in 3D you can see the problem (no floors yet).  Chief is adding some elevation data somewhere that is producing a topo several hundred feet off.  Is there an offset factor somewhere that can correct this?

[dshall]

I looked at the file and I took a screen shot of what I changed.  I'm not sure what else I can say.  When I made the change the terrain was essentially flat.

[glennw]

You need to supply more elevation data to enable the terrain to build correctly - the 4 elevation points are not enough.

You will find it easier to use Elevation Lines or Splines than Elevation Points.

An Elevation Line is really just elevation points at about 2'0" centres.

 

Or, you could change the Terrrain Surface Smoothing to Linear - this will smooth out the peaks and troughs..

[dshall]

11 hours ago, Griffin said:

Thanks for the reply.  

 

I'm not even getting that far.  If you look at the file I uploaded  in 3D you can see the problem (no floors yet).  Chief is adding some elevation data somewhere that is producing a topo several hundred feet off.  Is there an offset factor somewhere that can correct this?

 

I must apologize,  I thought I understood terrains.  I think Glenn's advice is good....  use terrain lines......  I will go so far as to say that it is a bug or it does not  behave as I would expect.  

 

This is probably the best advice Glenn gave you... "Or, you could change the Terrrain Surface Smoothing to Linear - this will smooth out the peaks and troughs.."

[dshall]

I have been doing terrains a long time.  I can almost always get a terrain I like.......  via my methods.

 

The fact that I could  not fix/understand the issue with your terrain tells me I should take a class in terrain building.

[glennw]

 

3 hours ago, dshall said:

 I will go so far as to say that it is a bug or it does not  behave as I would expect.

Scott,

 

You may need to take that class in terrain building.

The Subfloor Height Above Terrain setting has nothing to do with the shaping of the terrain (apart from the Flatten Pad setting).

Subfloor Height Above Terrain only allows the user to set the relationship (the relativity) between Chief's zero floor level and the terrain level.

I don't think it is a bug, I think the terrain just needs more elevation data.

I never use Elevation Points  - I always use Elevation Lines/Splines or Elevation Regions, etc.

 

If you read the manual:

Chief Architect requires many points to make an accurate approximation of your site. Even small sites may require over a hundred points to generate an accurate model of the terrain if it is sloped

 

Elevation Points are most effective when they are imported. When adding elevation data manually, use Elevation Lines and Splines instead. See Importing Elevation Data.

 

PS.

There were 4 elevation points in the original file, not 3 - one in each corner.

I was just having another look at the terrain pic you posted.

It is a bit hard to tell because the elevation points are small and feint, but it looks like you have deleted 3 of the elevation points and only left the one in the top left hand corner.

Or you may have reduced the size of the terrain so as to exclude the elevation points - I think I can just see the bottom 2 down below the terrain.

But I can definitely only see the top left one inside the terrain perimeter.

Guess what - if you only have 1 elevation point - you get a flat terrain.

[Griffin]

Thanks for the replies everyone.  Adding more elevation data helps, but does not eliminate the underlying issue which I think is a bug using data points.

 

I ended up contacting tech support and they provided the following response.

 

"Thank you for contacting Technical Support. There are two factors contributing to this type of unexpected terrain generation: the terrain elevation data values are quite high and there are not enough elevation data points for the program to correctly interpolate a more expected flat terrain. The larger the terrain area, the more data points would be needed, and expected, for the terrain to generate correctly. In a generally flat terrain, this shouldn't normally be a problem of course, which brings us back to issue of the elevation data itself. The values are quite high, I understand they've been entered in at sea-level heights, this isn't normally a problem either, since all Chief Architect is doing is calculating the difference between two points and the distance between, and generating terrain accordingly, as such, two terrain data points at 10,510 and 10,500 are no different than points at 510 and 500, or 10 and 0. However, because of the distance between each point, and the height of the elevation, the program is unable to properly determine how to interpolate the terrain information correctly. The simple fix is: add more Elevation Data. I've attached two screenshots, one where I've placed a Footprint converted to a flat region, as well as a few additional data points - in this scenario, if there is one less data point, the terrain goes south again. In the other screenshot, an array of points have been added at 30'40' apart, and the terrain generates normally.

While this is a relatively simple fix, I have sent these plans to our development team to look into the terrain code to see if this type of behavior can be avoided in these types of scenarios. Thank you for providing these plan files, I hope this helps you proceed with completing your plan.

Taylor
Chief Architect Technical Support"

[dshall]

On 4/22/2017 at 3:59 AM, glennw said:

 

Scott,

 

You may need to take that class in terrain building.    MAYBE SO

 

 

On 4/22/2017 at 3:59 AM, glennw said:

The Subfloor Height Above Terrain setting has nothing to do with the shaping of the terrain (apart from the Flatten Pad setting).

Subfloor Height Above Terrain only allows the user to set the relationship (the relativity) between Chief's zero floor level and the terrain level.

I don't think it is a bug, I think the terrain just needs more elevation data.

I never use Elevation Points  - I always use Elevation Lines/Splines or Elevation Regions, etc.

I DO NOT USE ELEV POINTS EITHER

 

If you read the manual:

Chief Architect requires many points to make an accurate approximation of your site. Even small sites may require over a hundred points to generate an accurate model of the terrain if it is sloped

 

Elevation Points are most effective when they are imported. When adding elevation data manually, use Elevation Lines and Splines instead. See Importing Elevation Data.

 

PS.

There were 4 elevation points in the original file, not 3 - one in each corner.

YES,  THERE WERE 4,  I MUST OF MISSED ONE,  I DID NOT NEED TO DELETE 3 OF THEM,  BUT MAYBE I DID,  I CANNOT EXPLAIN WHY I THOUGHT I HAD A SOLUTION

I was just having another look at the terrain pic you posted.

It is a bit hard to tell because the elevation points are small and feint, but it looks like you have deleted 3 of the elevation points and only left the one in the top left hand corner.

Or you may have reduced the size of the terrain so as to exclude the elevation points - I think I can just see the bottom 2 down below the terrain.

But I can definitely only see the top left one inside the terrain perimeter.

Guess what - if you only have 1 elevation point - you get a flat terrain.

THAT MAKES SENSE

 

I suppose what confuses me is why the  center of the terrain is lower than his defined  points?  IOW,  why isn't it higher?  IOW,  what defined the height of the low  point in middle of terrain. 

[Joe_Carrick]

Small flat terrain regions in place of the points would work much better, assuming you don't want to use terrain lines.

[Chopsaw]

On 4/21/2017 at 6:26 PM, dshall said:

 

Scott if you look closely there are four elevation points visible. One inside the terrain and three outside, two below and one offset proportionally to the left at the top.

 

Put those four points back within the terrain perimeter ( near the corners ) and then see what the subfloor setting will do.

[dshall]

Okay guys,  I have attached to screen shots,  the ugly one is griffin's,  the better screen shot is mine....  what is the difference?  the  delta between elevation points is the same....  but griffin's elev points are x + 800',  mine are simply x + 0'.

 

So here is the question.......  what would you  do to Griffen's plan to get a topo as good as mine........ remember,  I  think the  delta between elevation points for both plan is similar.  THE ELEVATION OF THE POINTS ARE WITHIN 5'  OF EACH OTHER.

 

Griffin's elevation are from 850' to 855',  mine are from 0' to 5'......... why do we get terrains the are so different?

 

dshd terrain 3.plan

[dshall]

36 minutes ago, Chopsaw said:

 

Scott if you look closely there are four elevation points visible. One inside the terrain and three outside, two below and one offset proportionally to the left at the top.

 

Put those four points back within the terrain perimeter ( near the corners ) and then see what the subfloor setting will do.

 

Did you do this?   What did you get?  Would you mind posting a  plan of what you got once you fixed it?

[Chopsaw]

49 minutes ago, dshall said:

Would you mind posting a  plan of what you got once you fixed it?

 

Scott I just wanted you to take another look as I thought you may have been onto something.  It does seem that Chief does need to do a little more work on terrains as it seems that it is factoring in a 0 somewhere in the calculations based on Griffin's plan.

 

However Glenn's fix seems to be the best for the available data.