So I have a site that I would like to grade from a perimeter up to determined elevation.
The base line is based on and existing surface and my design for the site.
The drawing I have attached shows this base line.
I would like to grade from this line up to an elevation of 190 at a 3:1 maximum slope (maintain 3:1 if possible).
**I have taken this line and made it a feature line and tried to grade from it. I have been able to grade it up to about 170 (using the grade to elevation criteria), then it starts to show issues (see image 1).
**This grading also seems jagged and irregular (see image 2), how can I stop this from happening?
**Another thing that seems to happen is that I get holes in my grading (see image 3), can I stop this from happening?
Does anyone have any idea of the best way to grade this!?!
Your help will be GREATLY appreaciated!
Solved! Go to Solution.
You are going to have those issues if you rely on the grading objects alone. I suggest you use the outline of the top of the grading as a guide and draw a featureline that is a close fit but use curves to smooth it out. Then build a surface using the bottom and top featurelines but not the grading. The resuting surface will not have exact 3:1 slopes due to your smoothing the top. You can adjust the featurelines as needed to get the slopes within acceptable tolerances.
You'll likely still have some rough contours. You can draw splines and add them as contours to the surface to smooth those areas out.
With regard to the problems shown in image 3, it appears the grading is having difficulties finding a solution for a 3:1 slope in that area. You'll need to decide how to resolve that (i.e. steeper slope, wall, etc). Also you might improve the grading by removing some vertices along the existing ground baseline that are causing steep slopes along the perimeter.
I will take your advice into consideration... I started to do what you said, then it crashed lol.
I graded to 168 (baseline peak at 164.5) and took that feature line, smoothed it etc and made a surface between the two and that seemed to work out ok, but then like I said it crashed. I can be less steep, just not more steep. The eastern side of the line where it ramps up is where a wall is going to be. They chose to not wrap it around the corner though it seems like it would have been a good idea to keep that in the design.
I was hopeful that there was something simple that I was leaving out.
More ideas from anyone would be great... the more the better
I don't recommend using a featureline that was created from the grading as there could be anomalies in it (overlaps, etc.). That may be causing the crashing problem. Instead draw a fresh new featureline.
Also try deleting the grading after you are done with it and see if that stops the crashing.
Lastly, look for steep slopes along the elevations of the base perimeter featureline. Steep slopes can cause rough triangulation. Rather than use a featureline for the base, consider making an alignment, sample the EG surface and design a profile that is a close fit, but smooth it with vertical curves and/or flatten the sharp grade breaks. Then generate a featureline from the alignment and profile to use for your surface.
So here is what I have done to grade a mound from an irregular baseline:
1. Create the existing surface.
2. Draw the perimeter line.
3. Create a feature line from this and set the elevation to the existing surface
4. Adjust the elevations for drainage and to match my perimeter details.
5. Select the feature line and from the main modify tab choose the feature line fillet.
6. I set the radius at 10 meters and then chose "all".
7. I set the radius at 2 meters and then manually hit all the points that weren't picked up.
8. Since the topography varies along the line, I graded to an elevation just above the high point of my line at a 3:1 .
9. This created the grading as shown above except the NE corner did not have any holes in it, but the top feature line was still jagged. I extracted these contours for use later...
10. I explode this top feature line, then draw a new line (on the inside to avoid overly steep slopes) to clean up the edges. Set this line to the elevation used previously.
11. Create a feature line from this line but allow it to keep its own elevation.
12. Create an infill grading between the two lines. This worked pretty well, but in the NE corner, the grading ended up very flat, I wanted a nice corner so...
13. Take the lines extracted earlier and trim them so they can be used to fill in only the bad areas.
14. Add these lines to the surface as breaklines.
15. Grade from the top feature line to the desired top elevation.
16. A fairly good looking surface was created from this.
The only issue with this is that when I wanted to slightly adjust the toe of slope I couldn't just move the bottom featureline as the top one was not dynamic to this.
Looks ok though. Thank you
Of course this workflow will not be dynamic as you've noted. If you need to adjust the baseline, again use the grading object as a guide to adjust the top featureline.
Your criterior simply does not work with the geometry to avoid overlaps in the projection even upon some normalizing. Retaing wall would help