Large Topo For Terrain


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I have been asked by the client if I can use his PDF topo  to be able to add drives, existing trees he wants to keep, and site the new home as it relates to an existing home, and other existing features such as a boat dock etc. The entire site is close to 10 acres, the topo is quite large. I don't have access to a gps of the site area, I do have the USGS of the area but can't seem to figure out if I can / or how I could use it to any advantage.

In order for me to create a terrain of the entire area using the survey data I have to zoom way out, then the info is completely unusable. What would you experts do / or have done, if you faced / have faced the same issues?

Thanks!

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If it is a large pdf sheet 24x36, use as a temp tracing layer.

As Jon demonstrated in his image( excellent Job!) Chief is up to the task. 

 

I used this website for simple terrain data import test in chief. It worked really well!

geoplaner.com

once you go to the lot in the map window, you should see the lot boundary.

 

 

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I am doing a fairly large site topo right now.  I have a regular survey and a screen capture of the contours from our city's online maps.  I import the survey in and put it on its own layer, rotate as needed and lock it.   I do the same thing for the contour jpeg.  Then I use terrain elevation data spline lines and trace over the primary contour lines.  It is a bit hard to manage all the lines, but I zoom in on each contour line and it is not too bad.  Locking the trace layers is the key.

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BTW,  what is a large lot?  When does the lot become too big for CA to handle.  The examples I see here are not large lots in my mind.  CA handle's these quite well.  I think they are all under an acre.

 

I am working on a project now that has a 5 acre lot.  No problems yet and there is some definite elevation changes.  I think it would be good for us to keep track of when a lot becomes too big for CA to handle.  Is it 6 acres or 10 acres or 20 acres?  I do not know.  Glenn has done some larger lots and he has not had problems,  but I do not know how large they are.

 

Let's keep track of this and if you are working on a lot that is over 5 acres,  maybe you can post what your results have been.  When I finish my project,  I will post and let you guys know of my experiences.

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BTW,  what is a large lot?  When does the lot become too big for CA to handle.  The examples I see here are not large lots in my mind.  CA handle's these quite well.  I think they are all under an acre.

 

I had a question similar to yours a while back in the other forum.  Doug posted a reply that I believe stated that about 800' by 800' should be a safe limit.

 

What I have found is that I can go much larger than that, but at some point z fighting becomes an issue.  There are times when doing sun studies that I would like to have a much larger surrounding area than just the immediate lot or property.

 

I use TurboCAD Pro Platinum along with Chief, and there is a new feature there that allows for decent sun studies as well.  You can convert Chief terrain into solids there as well and slice to your hearts content.  But back to your question, I have not yet tried a large terrain in TC, but it does present a few more options.

 

I tried a 16 acre lot once in Chief with a hill in the background that probably doubled the total area.  It worked, but the z fighting made it more trouble than it was worth.

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33 acres...  Cure your z-fighting by increasing Scene Clipping>Clip Surfaces Within:

 

I set mine @ 600", but that's just habit.  I think 240" will cure most full overview funkiness.

 

This lot has a 70' drop defined by four Elevation Lines.

 

jon

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Bob, I would add the perimeter, then the primary contours.  See where that gets you.  Then I would start deleting every other contour until you hit the sweet spot where the software math and the terrain data are close.  Less CA math = good.  Too many drawn contours and elevation points = bad/slow

 

jon

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OK,

 

I'm interested as I tried this a few weeks back on an area about 20 acres and the plan became huge, digitally, and other than first try, was never able to get it to show correct in 3D.

 

If anyone wants to look and see what I did wrong, I'll post plan. The elevation data is very accurate for location at the 2' level. Too big to directly post, but link below. My best guess is that the terrain perimeter does not contain the whole area so CA is trying to calculate that? Not sure, but I can't see anything in any 3D views.

 

https://www.dropbox.com/sh/dn72aeufmdtnksj/AADwB4_1fTXUJjHvvcE6ywena?dl=0

 

And now I'm really confused. My 60Mb CA plan that I could not view in 3D was uploaded to DropBox with link above. I downloaded the file to test that link would work OK and was surprised to see that somehow it was now shrunk to about a 6th the size (11-12Mb)? No idea how that happens. I open the plan and can view in 3D and think my assumption on problem was actually right as I see CA has the not defined areas inside perimeter at the extremes.

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Jon,

Thanks. Now that it shrunk and I can see it I was able to see the issues and correct. It actually looks quite good. The terrain elevation lines were just traced by me over good data overlay in plan. I did extend the lines over boundary a bit and changed the shape of perimeter. My question to you or anyone is about " deleting" secondary lines. I assume all of mine are primary as drawn with the 2' elevation data. Should I just move those to the other "secondary" layer?

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Keith, I think you're missing my point re: drawn secondary contours.  Elevation data needs to be used sparingly on large lots or CA completely bogs down in its own math. 

 

If you look at what I posted, I deleted 80-90% of the red "secondary" elevation lines and kept to blue.  If you overlay your drawn contours with the generated contours, they are very similar. 

 

Let the software do it's thing and fill in the gaps.

 

jon

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