You know what I like about drawing my own contours?

Trimming The Funny Tail

I find Carlson very convenient for creating small topo projects, like for septic system designs. As to the funny tail, just pick "Trim" and do a crossing of all the contours, zoom in and pan around the contour perimeter picking the tails. Carlson trims the polyline to the nearest vertex.

This also works if a contour polyline needs to be stretched in the middle while the ends look OK. "Trim", select the polyline, "pick" a segment in the middle. That segment disappears, move one or both end segments, then "draw a line" endpoint to endpoint of the segments. That line will be on elevation and can quickly be rejoined to the contour.

Sometime you just all out forget to take a neccessary shot. The easiest way is to just insert a 3D node using your best topographic judgement. Seldom do these small projects require breaklines. I have neen doing that since AutoCAD 10.

For engineering projects breaklines make it all happen. If it is a low volume road shoot just the centerline, create a 3D centerline polyline then offset "Offset 3D Polyline" left and right plus down just follow the questions.

Paul in PA

Trimming The Funny Tail

> As to the funny tail, just pick "Trim" and do a crossing of all the contours, zoom in and pan around the contour perimeter picking the tails.

"pick" a segment in the middle. That segment disappears, move one or both end segments, then "draw a line" endpoint to endpoint of the segments.
>
..... The easiest way is to just insert a 3D node using your best topographic judgement. .
>
> Paul in PA

Yes, trim all the tails at once, light up the grips and stretch the endpoints. Very familiar with that process.

I use carlson's contouring routine on more than half of the small septic jobs and it does work good. I just find I can get exactly the contours I want by drawing them myself and using the DRAW SEQUENTIAL NUMBERS to label the contours. Then just light up the grips of each polyline and get them exactly the way the actual ground looked.

If you are getting the tails on your contours it is because you are not creating an inclusion boundary for the surface. Draw an inclusion boundary and that won't happen. If you want to extend then then just use the extend command on the contours...it may not be accurate but it's the same as drawing them further by hand.

If you skimp in the field, then you don't have the data to easily re-create the DTM or have an accurate DTM file. We give our DTM files to most of the engineers we work for and they use them as a base for their calcs and grading. A good base DTM file is essential for engineering, construction and development projects. It makes volume clacs, grading calcs, machine control, and more much easier. We charge for the information but tell the client that it is cheaper for us to do this right the first time than it is to pay the engineer to fuss with it after. They all go for it.

It's like running linework. It may take us a bit longer in the field (and not much) but it cuts my drafting time by 2/3. With one of my best party chiefs, I don't have to draw a single line most of the time. On top of that, all his linework comes in with 3D polylines under it so it makes for easy DTM creation.

We just did 15 acres of ground topo, in total it took me about 45 min to draft the entire map, topo, trees, linework, frame and all. Property was only approximate on this one so that was not an issue. Good and complete field practices and good field to finish setup let that happen.

Just my 2 cents...take it for what it's worth.

Tom

Tom

I always use an inclusion boundary, but I tend to push it too far...

My point is, I must draw my inclusion boundary well inside the area that was topo-ed to avoid the tails. This forces me to take many extra shots in the field.

And straighten out the jags that confuse the reviewers.

And remember to deselect the reflectorless shots on the peaks of buildings and tops of utility poles, etc

If you are not taking enough shots in the field to draw the contours without extrapolating then you are not taking enough shots. Eyeballing contours is a bad practice. The human eye can easily be fooled and be off by many feet.

I really miss doing complex contouring by hand. It was fun and a challenge sometimes. I like Carlson's contouring routines too. Very easy to edit a surface and re-contour.

You know what I like about drawing my own contours?

It's more accurate

Tom

And straighten out the jags that confuse the reviewers.

Use the Swap Triangle command in the surface menu. We rarely spend more than 5 min having to clean up DTM files. Drawing good breakines fixes most of that (our are drawn from the field linework automatically in 3D)

And remember to deselect the reflectorless shots on the peaks of buildings and tops of utility poles, etc

Point Groups based on description are created automatically, we make only a few minor adjustments to the groups based on noted shots by the PC.

I agree that it is sometimes easier but if you are giving that info to someone to use then it's not complete info and may affect their designs. Same with extending the contours or not getting top slope shots. It may have been fine many years ago but in todays high accuracy design and high liability world things have changed.

I guess it all depends on what you are working on but we generally get everything on every job. I know a few surveyors who don't carry elevations on non-topo projects and I think it's nuts. It takes no extra time and more than once I've been able to charge for a topo after the fact when we already have all the info to do it (on a lot of small sites the site features work fine as elevation shots so no extra ground shots are needed).

Tom

Tom

These are mostly 40 shot septic jobs that go nowhere. Even if the files do go to another user, they can turn on the points to judge for themselves as to the validity of the contours. They are usually jobs where we know where the components of the system are going and know where we need elevations. The rest is just window-dressing for the revierers.

AS far as carrying elevations, we usually don't bother on large acreages. Measuring up takes some time, and typing in target height slow us down some on a 60 setup day. One of the guys I work for leaves his DC at home and notebooks the data, so he only has to write down two numbers instead of 4.

I am apalled!! I have been drawing contours longer than many here have been drawing breath and the above statement is INSANE!!
"Streatch" contours??? "Interpolate" contours??? "Don't want to take that many shots in the field"??? Why take ANY at all? Just fudge it all because that is what you are doing.
What happens if your client needs to rebuild your surface for his design?? SURPRISE!! Your contours do not match his rebuilt surface?? It should. It MUST!!
What have you produced? A wad os sqiggley lines that mean absolutely nothing. That's a TON of liability that you are working with. Can't blame it on the software when your shoddy proceedures are revealed!!
As a cartographer, I feel the same way about the practices revealed here as you surveyors feel about "Low Ballers". There are two ways to do any job (1) Correctly, or (2) Fake it.
Remember, your client must be able to RELY on the data that you present. Where's the reliability when you fake it?

Ditto.

cpdent

> I am apalled!! I have been drawing contours longer than many here have been drawing breath and the above statement is INSANE!!
> "Streatch" contours??? "Interpolate" contours??? "Don't want to take that many shots in the field"??? Why take ANY at all? Just fudge it all because that is what you are doing.
> What happens if your client needs to rebuild your surface for his design?? SURPRISE!! Your contours do not match his rebuilt surface?? It should. It MUST!!
> What have you produced? A wad os sqiggley lines that mean absolutely nothing. That's a TON of liability that you are working with. Can't blame it on the software when your shoddy proceedures are revealed!!
> As a cartographer, I feel the same way about the practices revealed here as you surveyors feel about "Low Ballers". There are two ways to do any job (1) Correctly, or (2) Fake it.
> Remember, your client must be able to RELY on the data that you present. Where's the reliability when you fake it?

There were a few guys in my area who approached a septic design like you do. They are mostly out of business now. They would spend have the day taking hundreds of shots in the "don't care" areas, but miss the important shots where the house, field & tank goes. They would waste time topoing (the middle of) wetlands when we have to stay 75' away from them anyway.

We generally have the house, tank and field areas figured out before we even pull out the total station instead of blind intensive topo.

And for the record, All contouring routines use interpolation. And any extrapolation I do, is only steatching another 10 or 20 feet on a constant slope area of no importance.

cpdent

"And for the record, All contouring routines use interpolation. And any extrapolation I do, is only steatching another 10 or 20 feet on a constant slope area of no importance."

Constant slope? Rrrreeeeeaaaallllllllyyy! Calibrated eyeballs are a big advantage I suppose. 10 or 20 foot streatch because you did not want to shoot it? Rrrrreeeeaaaaaallllllly!! If one or two more shots will make you go bankrupt, them you are doing something else wrong.
I fully realise that all software interpolates between shots,(RRRRREEEEEEEEEEEEEAAAAAAALLLLLLLLLLYYYY!! NO SNIT!!), but I believe you will find that they do it MUCH more accurately than a 10 or 20 foot streatch. Believe me, I know how the stuff works. I have been doing it by hamd or on a Kelsh stereo plotter or on a computer for over 40 years, it is my specialty, so I am not quite the fool that you think I am.
If the area is "of no importance", then wht streatch a contour? That's just a slipshod work standard that would not fly in my office, or in my state for that matter.
Sewer dewsign goes wrong because of your "streatch" and you will bwe in it for BIG bucks. Your liability.

cpdent

> "And for the record, All contouring routines use interpolation. And any extrapolation I do, is only steatching another 10 or 20 feet on a constant slope area of no importance."
>
> Constant slope? Rrrreeeeeaaaallllllllyyy! Calibrated eyeballs are a big advantage I suppose. 10 or 20 foot streatch because you did not want to shoot it? Rrrrreeeeaaaaaallllllly!! If one or two more shots will make you go bankrupt, them you are doing something else wrong.
> I fully realise that all software interpolates between shots,(RRRRREEEEEEEEEEEEEAAAAAAALLLLLLLLLLYYYY!! NO SNIT!!), but I believe you will find that they do it MUCH more accurately than a 10 or 20 foot streatch. Believe me, I know how the stuff works. I have been doing it by hamd or on a Kelsh stereo plotter or on a computer for over 40 years, it is my specialty, so I am not quite the fool that you think I am.
> If the area is "of no importance", then wht streatch a contour? That's just a slipshod work standard that would not fly in my office, or in my state for that matter.
> Sewer dewsign goes wrong because of your "streatch" and you will bwe in it for BIG bucks. Your liability.

That's one of the funniest posts I've read in a while:-D

You won't catch me extrapolating contours out of an area I didn't topo....If I need it, then whats 5 minutes to get that extra shot or 2 or 12???

call be insane but

a gravity septic design will never fail because of an inaccurate contour on the uphill side of the house.

> You won't catch me extrapolating contours out of an area I didn't topo....If I need it, then whats 5 minutes to get that extra shot or 2 or 12???

No, but the engineer you email the data too would certainly stretch the contour out to satisfy a bureaucratic requirement which is of no importance to his design. That's the difference. We are the end-users of our data,

isnt that what the as-built is for? lol

yes, I was thinking the same thing.

I draw a boundary around my outer shots and don't get tails.