Offset variable feature line to known elevation?

[htothethird]

Can't seem to figure this out.  Can I use the offset feature line to offset an unknown distance, to a known elevation at a known slope?

Ex - I have a rockery along the property line.  This elevation is set, yet varies from 350 down to 340.  Then I have pad grades at elev. 336.  Is it possible to offset the toe of my rockery featureline to the elevation 336 at a grade of 2:1?

Thanks!

I know this is possible using grading groups, but it would be fast to do it from a feature line offset, so that's what I'm looking for.

[owenmull]

Without using a grading object, I do not believe so. The Stepped Offset function under the Feature Line dropdown requires both horizontal and vertical offsets to be known. Without grading your toe, this is not inherently possible.

Why not just grade it? The grading will create a feature line like what you are aiming for.

[htothethird]

I know, but it just seems to be extra steps.  I always try to do the shortest amount possible.  🙂

Just so I'm clear on the grading groups, this is the way we do it (maybe there is an easier way)

Create a temp surface using the pad grades, then use create gradeing using the temp as the target surface.  Then grade to catch at a 2:1 slope.

Only proplem i have with this is that if the pad feature line is farther than 2:1 it won't give me information for that area.  Make sense???

[DaveM]

You can grade a feature line to an elevation as opposed to a surface, but you chance the pad being an undefined shape.

[owenmull]

I think I follow.

Does this generally illustrate your problem, more or less?

A.) Depicts where your grading intersects your temp surface.

B.) Depicts what happens when the surface does not intersect your temp surface.

C.) Depicts a possbile fix. Create an arbitrary surface a good distance below, grade to it (or grade to an elevation well below target, same idea) then grade from edge of temp surface to that grading, trim out the excess from the resulting surface(s).

Does this help? Am I close?

[htothethird]

Owen,

Yes that is what I meant.  Just frustrating when my grading reaches the pads at some locations and not others.  Then I have to extend as you suggest. 

Always hoping and searching for easier ways 🙂

[Neilw_05]

I think your terminology is distorting your view of the task. What you are describing is not an offset but rather a projection. As you know there are tools for creating projections but apparently those tools are not adequate for your needs. I've heard of custom tools to create daylight featurelines without using gradings but I've never heard of any for creating one at a target elevation.

[doni49]

---

@htothethird wrote:

Can't seem to figure this out.  Can I use the offset feature line to offset an unknown distance, to a known elevation at a known slope?

Ex - I have a rockery along the property line.  This elevation is set, yet varies from 350 down to 340.  Then I have pad grades at elev. 336.  Is it possible to offset the toe of my rockery featureline to the elevation 336 at a grade of 2:1?

Thanks!

I know this is possible using grading groups, but it would be fast to do it from a feature line offset, so that's what I'm looking for.

---

What do you mean by the elevation is set, yet it varies?

[doni49]

If I understand Owen's explanation correctly, then it sounds like a custom sub-assembly with a corridor would be helpful (corridors aren't limited to roads).

1) create an Auxiliary Link that represents what he called the grading (the one that went too far).

2) Then from Object 1, create a point at your specified slope that intersects with the AuxLink.

3) Create links from Object 1 to the point created above.  Then create a link from this point to Object 2.

[doni49]

---

@doni49 wrote:

If I understand Owen's explanation correctly, then it sounds like a custom sub-assembly with a corridor would be helpful (corridors aren't limited to roads).

1) create an Auxiliary Link that represents what he called the grading (the one that went too far).

2) Then from Object 1, create a point at your specified slope that intersects with the AuxLink.

3) Create links from Object 1 to the point created above.  Then create a link from this point to Object 2.

---

I put together a quick example of what I mean.  Object 2 (I'm guessing the "Rockery" -- although I'm not sure what that's supposed to be) would have an alignment, profile and corridor.  Object 1 would have an alignment.

Then the SA is set to create P2 at an offset target (I would assign this to the Object 1 alignment).  Then there are two slope paramaters -- slope 1 will be used to create L1 and Slope 2 will be used to create L2.

I created an AuxLink from P1 (Object2 alignment) at a slope controlled by the Slope 1 parameter.  Then I created an AuxLink from P2 at the slope controlled by Slope 2 parameter but the sign (neg/pos) is the opposite of what's specified by putting "-Slope2" in the point's Slope field -- this makes the link go up instead of down.  P3 will be created from the intersection of AL1 & AL2.

Open the attached zip file then extract the contents -- it was created in SAC 2012.

EDIT:  I answered my own question (what's a rockery).  http://www.wisegeek.com/what-is-a-rockery.htm  Snippet:

A rockery is a landscaping feature which is made by arranging rocks and plants, often in a way which mimics a mountainous or alpine environment. In the West, rockeries have been popular since at least the 17th century, when they were introduced to Europeans from Asia. In Japan and China, the art of creating rock gardens is over one thousand years old; some very fine examples of rockeries can be seen in these nations. Installing a rockery is relatively easy, although you may want to consult a landscaper who can help you with subtleties of placement and arrangement which will make the rockery more visually striking.

[htothethird]

Sorry - guess that was a poor explanation. 

What i meant is the the elevations are set due to the to existing grade we are tying into and I can't change that, yet due to maximum rockery heights, I'm limited to 8' and so the Top of my wall varies in elevation.

See the snapshot below for what I mean.  I had to use grading groups to get the 2:1 slope in the rear yard from the toe of the slope to the pad grade.

[htothethird]

Here's a better snapshot, contours too dark in the first

[doni49]

Thanks for the clarification.  It still sounds to me like a corridor would be helpful here.  Can you sketch this up in cross section view showing what it would look like?  Show what will be constant and what will vary (and tell us HOW it will vary/what will control it).

[htothethird]

Here is a quick section.  I create a feature line at the top of the rockery, then offset it to create the toe.

From there is where I'd love to find an easier way to grade down to the pad.

I've thought of using corridors but the depth of the pad varies, either due to grade or existing conditions (such as a tree in the rear of the lot being saved, thus pushing the wall forward in the lot)

[Neilw_05]

I would consider using infills for the pads. The infill will be dynamic to changes in the gradings.

So the workflow would be:

1) Create a FL for the top of the rockery and drape on EG.

2) Create elevation target gradings at 2:1 to your pad elevations.

3) Add infills to fill the pad.

Does this not work for your scenario?

[doni49]

The section makes it pretty easy to understand.  I do have a few questions about it.

1) does the width of the slab (distance X) vary or is it constant?

2) you said before the rockery height will vary (distance Y).  But you didn't say that here.  Does it vary too?  Or just the width you noted?  If it does:  what controls the height?  Would it be the height above the slab?  2) in what increments does it increase?

3) Can you create an alignment (including a profile) that represents the Property line and one for something on the other side of the section (such as one side of the slab or idealy where this all meets the EG.

[doni49]

Also:

[htothethird]

X varies (based on the rear lot grading from the toe of the rockery)

Y varies.  With this much elevation difference it will most likely be held at the 6' max, but it also varies along the lot horizontally.  By this I mean the southwest corner of the lot may be 3' higher or lower than the southeast corner.  So the rockery top and toe would also vary that same 3'.

Height of Y is based on the existing grade, as shown on the right side of the property line in the section. 

Not sure i understand your #3

And the distance between the back of the walk and the pad grade is generally held at 10% and up one foot from the back of sidewalk grade, thus a distance of 10.

[doni49]

---

@htothethird wrote:

Not sure i understand your #3

---

For this to have a chance of working with a corridor, you'd need two alignments -- each with their own profile).  Then the corridor would "follow" one alignment (the one that's assigned to the corridor) and then one (or possibly more) points would target the other alignment to get the horizontal location and its profile to get the elevation.

So I am asking if you have a line (at least in plan view) representing the property line and one representing something on the other side (possibly the curb).