# Sloped elevation line, Grading Plan

## Recommended Posts

I am working on a grading plan for my building site.

I need to create terrain slope in x and y directions simultaneously, i.e;

slope down from the sides of the house to the sides of the lot and slope down from the back of the lot to the front.

It would be quite simple to do if I could add sloped elevation lines, but elevation lines are a constant elevation.

Any suggestions on how to accomplish this?

I tried a Terrain Break line with an elevation point at both ends hoping it would create a sloping "ridge" along the Break line,

but the effect of the elevation points are very local to their placement.

It seems I would need to externally calculate and then place a large matrix of elevation points to accomplish my goal.

There must be an easier way?

Regards

##### Share on other sites

Use Elevation Lines (not Elevation Points) that define the "constant elevations".

ie, lines that are level - same as contour lines.

I don't understand why you would do anything else.

It sounds like you are trying to relate the ground slope to your site boundaries - they are two independent things.

Ignore the site shape when drawing your Elevation Lines.

##### Share on other sites

Thank you Mark,

But how to do as you say in both X and Y?

Say the most important is sloping the lot down from back to front.

So I could create elevation lines parallel to the X axis from left to right terrain boundary every 10 feet,

down 10/4 (for a 1/4 in 12 slope) in elevation.  Lets call these primary elevation lines.

Now how do I create slope from side to side?

If I create elevation lines now at right angles (parallel to the Y axis) to those first created, won't they be in conflict with those parallel to the x-axis?

I can certainly see how to create slope in one axis, but not in both at the same time unless I draw small individual elevation lines (secondary) parallel to the Y axis,

in between each primary elevation lines.  But this I think is going to create little 10 foot by ten foot flat areas .  Maybe CA will smooth it a bit?

So with a 70 by 40 (50 actually, but keep the numbers divisible) foot lot at 10 feet between elevation lines, I'm going to need to draw 8 primary elevation lines,

and 40 secondary ( 5 between each pair of primary elevation lines at 10 foot intervals), for 48 elevation lines.

But, I don't think this will work either though as the primaries are going to be set to a constant elevation parallel to the X axis, while the secondaries are going to be trying to lower that as it gets closer to the side lot lines.

So I think I will need to break the 8 primaries into 5 little pieces each and forego any secondaries for 40 elevation lines and hope CA smooths them somewhat.

So, I'm suspicious that the same slope in X and Y will result in contour lines of constant elevation that will be circular arcs (X^2+Y^2=Z^2),

not the easiest thing to draw accurately with the elevation spine tool.

As I originally said, surely there is a simpler way?

Thank you for taking the time to converse about the issue.

Regards

##### Share on other sites

9 hours ago, moreauj said:

It seems I would need to externally calculate and then place a large matrix of elevation points to accomplish my goal.

There must be an easier way?

Yes that should work if done properly but the easier way is to place your elevation lines on an angle so they influence both X and Y at the same time.  It seems you are way over thinking this.  Yes if you want delicately curved elevation lines you will need to accurately plot out calculated points but if you just need a rough layout then the angled lines should work fine.

##### Share on other sites

You lost me!

As Chopsaw said - you are overthinking it.

It is really pretty simple but you seem to be making it really complicated.

Do you know what a contour line is?

A line that joins points of equal height.

Google contour lines if you need clarification.

So...all you need to basically do is draw contours using the Elevation Lines - forget Elevation Points.

Drawing retaining walls, flat areas etc, come in the second lesson.

##### Share on other sites

23 hours ago, moreauj said:

I need to create terrain slope in x and y directions simultaneously, i.e;

Not easy to do since Chief is always trying to “smooth” out the different elevation regions.

If you’re trying to create an idealized terrain to show slopes in the various elevations and 3d view, then what I often do is to use 3D solids and 3D mouldings to create the terrain. (A very geometric but precise terrain)

This way I can precisely create the slopes in cross sections and then convert the shapes into 3D solids and adjust these objects in plan view to create the slope away from the building and simultaneously create the water drainage slope from the back of the property to the street.
After you create all theses various wedges and pyramid type shapes you can join then all into one object.

The downside is that Chief won’t recognize the resulting 3D solid/terrain as a true terrain.
So, when you want to place trees, shrubs, fences, etc., the objects won’t snap/gravitate to the terrain.

What I do is, export the model to Twinmotion which does allow for placing of objects on my “terrain”.

That is where I do the landscaping stuff anyway in my models.

##### Share on other sites

Yes glennw, as an engineer and mariner with over 30 years of field survey experience, I'm pretty sure I have a good idea of what a contour line is.

So, the most complete answer is from Chopsaw, thank you Chopsaw.

As slope is changing in both x and y at a constant rate, this can be represented as two linear equations.

The intersection points of the two linear equations result in linear contour lines at an angle to the slope i.e. at a diagonal,

as opposed to my first suspicion that this might result in contour lines of circular arcs.

If the slopes are equal in x and y, the angle of the diagonal contour lines will be 45 degrees.

I verified this by creating a spreadsheet of points sloping 1/4" per foot in both X and Y and importing to CA.

The resulting terrain contour lines are attached.

Thank you all for participating and resolving the question.

Regards

As an engineer, mariner and years of field survey work, I'm well aware of what a countour line is.

I can assure you simulktaneous slope in orthagonal directions (x and y)