Having a devil of a time getting contouring to work properly on some pretty flat drainage ditches and am looking for any advice on what others have found to make it work properly. Any tips or steps out there that anyone knows that could assist me? I'm not looking forward to chasing down well over a couple of miles of ditch contours! Any process that any of you use on the flat stuff could be very helpful.
Sounds like you didn't have enough break lines
Make all your break lines 3d polylines and it should work excellent. Check your interior and exterior tmesh lengths. Only use points polylines and 3d polylines. I love Carlos contouring. Easy easy easy. Way easier than pacsoft.
There's probably a bunch of things that it could be. When you're saying "some pretty flat drainage ditches", how much relief are you speaking of? What contour interval are you setting? Min & Max space between points?
I have 3d polys at the tops, toes, and cl's but it still comes out wonky. I've had it work beautifully in the past so it may be a setting. Could you expound briefly on the t mesh?
I mean flat as in very little grade. 80-90 ft. cross sections, 1 ft. contour interval, 2-6 ft. ditches.
I'd have it draw the t mesh and make sure that it is honoring the 3-d polys. If not, under Triangulate and Contour on the Selection tab make sure that you have clicked the check box for 3d polylines.
The 3d poly box is checked.....mesh settings interior 5,000 exterior 10,000. Min. contour length is .5.
I wonder what would happen if I increased the min. contour length significantly?
Your interior/exterior settings seem high. Most of my topos have points spaced no more than 50 feet apart so I have mine set to 100-interior 200-exterior. It might be worth using the PrintScreen button to grab a snapshot of the contours you're getting and pasting the result into Paint then uploading the image here. Someone might be able to spot the problem based on how the contours look.
> The 3d poly box is checked.....mesh settings interior 5,000 exterior 10,000. Min. contour length is .5.
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> I wonder what would happen if I increased the min. contour length significantly?
That's your problem. The interior is a lock on how far you're willing to let it interpolate the contours. So, you're allowing it to look at points 5000 feet away inside the inclusion area and 10000 feet away on the exterior.
If you're getting shots no more than 50' apart, drop the interior down to 60' and the exterior down to 100' and I bet it gets WAY WAY WAY better.
> I have 3d polys at the tops, toes, and cl's but it still comes out wonky. I've had it work beautifully in the past so it may be a setting. Could you expound briefly on the t mesh?
The T mesh, T net, whatever, is the triangle that it uses for the cross interpolation between points. If you ever contoured long-hand, then you may not get the terminology, but understand that if you had 4 points in a grid, you interpolated around the perimeter of the box, and then the two diagonals. That's the mesh that I'm talking about. PacSoft called it TNet. At any rate, your interior and exterior distances that are shown below are what you're allowing it to use to interpolate by, so instead of using the closest points, you're allowing it to run the full length of the project and try to get 1' contours. You and I know it won't work. Back those distances up to the grid distances that you're following and recontour.
Obviously, none of us still do a true "grid" so maybe some of the cross ties in the tmesh are a little long and you'll see that the triangles won't connect. That's when you have to start opening up your tolerances in the interior and exterior until it gets right.
You're like three clicks away from getting it fixed dude. Hang in there.
As long as you define the breaklines/slopes/banks correctly in the field, the contouring should be pretty simple.
Send me your dwg if you want.
As I have used Carlson Survey over the years, I have found out that sometimes a little "over kill" is a good thing. I'll tell you how I do it and a bunch of folks will come on and tell you, "No. You do not have to do that!!". I understand all of that, but it is what seems to work best for me and , once set up, takes no additional time.
First of all, I code all of my breakline featurse such as ditch centerlies, tops, toes, etc. to be drawn as 2D AND 3D polylines. I also set them as "Hard Breaklines".I put the 3D polylines on a layer "SRF-FLT". All of them. (This way the ex-LDD users will know where to look for them.)
When I am ready to build the surface I "Shrink wrap all of my points and then edit that poly to give me the edges I want for those outer contours.
Then I turn on that layer and the SRF-FLT layer and "Draw, Locate Points" with the them inserted at their proper Z values.
Then I go through the surface set up and tell it to use the Carlson points AND the CRD file for the project. (There's the over kill everyone will whine about. It works for me, so I do it, no matter what the "experts" may say.)
Then I build my surface. AutoCad has always been real strange about the way it handles breaklines. It's not real consistant sometimes. Using the method above seems to make it more consistant with handling breaklines.
Carlson has one of the best contouring packages out there. It's easy to use, you just have to give it ALL of the data it needs and it will hum through the biggest of jobs. Once you get used to it, you will see how simple it really is, even down to merging tins and all that other stuff that drove you crazy in AutoCad.
