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Working with Elevations

 

 

 

 

Everything TPC does with coordinates is 3D, meaning it computes elevations.


Entering Elevations

Elevations can be entered directly for a point in either the Points Manager or the Traverse View if the elevation column is turned on.

When you enter an elevation in the Traverse View, TPC automatically protects the elevation of the point. This feature allows you to run levels through points that you located with a total station that computes an elevation. In this case, the elevation you enter takes precedence over any elevation computed from the slope distance and vertical angle.

See Entering Elevations.


Computing Elevations

As a rule, elevations get computed automatically in TPC. When you inverse a mid-point, TPC assigns the average elevation of the end points to the mid-point. When you compute terrestrial observations with zenith angle and slope distance, TPC computes an elevation. When you compute a point in the Compute Coordinate dialog, TPC gives you options to accept the computed elevation or enter an elevation to hold. So you get the picture. Elevations are computed pretty much everywhere.  See Computing Elevations.


Picking Elevations from a Drawing

In any COGO dialog with an elevation followed by a [>] pick button, you can select the [>] pick button, then select any object in the current drawing. TPC will get the elevation from that object an place it in the dialog.


Carrying Elevations in a Traverse

You can start a traverse at a known elevation, shot one or more benchmarks while you traverse, use stadia, enter instrument heights and target heights and shot zenith or vertical angles, enter vertical distance and lots more as you traverse.  All of these options are available to be used together or my themselves. See Carrying Elevations in a Traverse.


Protecting Elevations

In both the Points Manager and the Traverse View, you can identify points with projected elevations one three ways

right-click a point and choose Survey Point Properties. The status tab will indicate whether or not its elevation is proteced.

turn on the Status column for the view and look for the letter E, indicating that point's elevation is protected

Press F9 in either view to display the Format dialog and left-click the Format Fonts tab. You can choose a color and style for Protected Points.

See Protecting Elevations.


Elevation Tolerance

TPC considers two points to have the same elevation if their elevations differ by less than the Elevation Tolerance.  TPC's default value is 0.1 survey units, but you can change this to your preference.


Elevation Decimals

As a rule, TPC includes separate user decimal setting for elevations vs X/Y coordinates. The Program Settings, Decimals dialog is a good example.


Sorting Elevations

In the Points Manager, you can sort elevations by left-clicking the Elevation column header. Each left-click changes it to Sorted Ascending, Sorted Descending, Unsorted.


Benchmarks

One of the ways you can carry elevations in a traverse if via benchmarks.  Benchmarks are points of known elevation you can tie in the field, as needed, to establish the elevation of the optics of your total station.

TPC has a special traverse point type called BM for benchmark, that does just that. When you shoot a benchmark and set it's point to type BM in the traverse view, TPC back-computes the elevation of the total station optics using the measured data along with the target height to the benchmark. As such, you do not need to know the elevation of your occupied point.


Translating to a Known Elevation

If all the elevations are correct relative to each other, but they do not match a target elevation for the project or a known elevation you tied, you can always translate just the elevations of part or all of a survey, to the correct elevation.

open the COGO Translate dialog

use the What list to select the entire survey to translate or just the points or traverses you want

use the options in the translate dialog to translate by a specific amount of elevation or so that the elevation of an existing point matches a known elevation

do the translation


Geoids

TPC can compute geoid heights (separations from the ellipsoid) and use them to convert elevations to ellipsoid heights and visa versa.


Vertical Alignments

TPC allows you to compute vertical curves, using vertical points of intersection (PIs), stations and elevations. These vertical curves and the tangent grades between them form vertical alignments that can be applied to a traverse.


Profiles

TPC computes and draws Profiles. Take a look at the Profile Mode command in the Drawing View.


X-Sections

TPC computes and drawings X-Sections.  You can even select multiple x-sections and stack them on a single page with a user specified offset between each and a grid for each.


Adjusting (balancing) Elevations

When you adjust coordinates X & Y, you can also adjust elevations.


Surfaces Elevations

Surfaces interact with elevations in a number of ways. We'll list some of them here. See Surface Elevations.

Cuts and Fills in the Stakeout Report

TPC can generate a stakeout report, showing the as-staked position, the design position and the differences in X/Y/Z.  The elevation differences are also reported as a Cut or Fill value.

Cut Sheets from Surfaces

TPC can created a cut sheet report for points found in a traverse or drawing object to an existing surface.  TPC uses the X/Y coordinate position of each point to compute the corresponding elevation on the surface, then reports the elevation difference between that point on the surface and the point as a cut or fill.

Creating Transects from Surfaces

You can draw a line, called a transect, across any surface and TPC will compute a point each time that line intersects a TIN line for that surface. The points are sequenced from the beginning end of the line and you end up with a transect that be drawn in profile mode to show the distance (station) and elevation of each intersection point created.

Moving Survey Point Elevations to a Surface

You can use the Move Elevations to Surface command to move existing survey points to a surface.  For example, you might create a grid of points to stakeout a finished grade surface you created. Just create the points, then move them to the Finished Grade surface.

Specifying TOPO Points for Surfaces

When it comes to elevations and surfaces, you may not want to include every point in a surface. For example, if you shot the top of a fire hydrant that stood 2 feet above the ground, you would not what that shot to be included in the surface.

To accommodate the common scenario, TPC does NOT rely on elevations to indicate topo point, but instead, has a separate Topo Point designation that can be turned On or Off for individual points or all the points in a traverse.

See Editing Topo Points.

Restricting Elevations of Surfaces

In the Surface dialog, you can restrict the elevations of the source points.

Restricting Elevations of Contours

In the Contours Dialog, you can restrict the contours so that only the contours between minumum and maximum values (inclusive) are drawn.


Least Squares

TPC least squares routines can do 2D or 3D adjustments.  The 3D of course, adjusts the elevations along with the X/Y coordinate values.


Related Topics

Entering Elevations
Computing Elevations
Protecting Elevations
Elevation Tolerance
Decimals Dialog
Benchmarks
Carrying Elevations in a Traverse
Geoid Heights
Vertical Curves
Vertical Alignments
Profiles
X-Sections
Adjusting Elevations
Creating Cut Sheets from Surfaces
Transects
Editing Topo Points
Least Squares

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