Distance Types are available in the Traverse View | Format View, Advanced tab. You can choose a coordinate distance type or a geodetic distance type from the Distance pulldown.
The Traverse Views uses the following abbreviations for distance column headings.
Grid Dist -
inversed grid distance between coordinates
Ground Dist - inversed grid distance between
coordinates scaled to ground distance
Geo Dist -
geodetic distance (geodesic) between two geodetic positions either on the
ellipsoid surface or scaled to ground distance
Coordinate distance types like 'Grid Distance' and 'Ground Distance (at project elevation)' are based on cartesian coordinates, scale factors and elevation factors.
When you enter a distance in a Traverse View, TPC looks at the traverse format to determine what type of coordinate distance you are entering, reduces the distance to the corresponding grid distance, then computes the grid coordinates of the foresight.
When you recall two points and display the coordinate distance between them, TPC first inverses the grid distance between the two points then scales the distance to distance type being displayed in the view.
When you enter a geodetic distance in a Traverse View, TPC looks at the traverse format to determine what type of geodetic distance you are entering and scales the distance appropriately before computing the foresight. For example, if you have selected the 'Geodetic Distance (project elevation = 2,500)' as the geodetic distance type for a traverse, TPC will multiply any geodetic (ground) distance you enter by the the approriate elevation factor to reduce that distance to an equivalent distance on the ellipsoid surface, then TPC will computes the geodetic position (geodetic direct) for the foresight on the ellipsoid surface.
When you recall two points, TPC makes sure it has geodetic positions for the two points then computes the geodesic between then and scales it to the distance type displayed in the view.
If you enter a slope distance, the slope distance will first be converted to the equivalent horizontal distance. Depending on the distance type you selected, this can be a coordinate distance or a geodesic distance. It is this horizontal equivalent that is then used to compute the foresight.
Vertical distance is independent of ground distance scaling. It is simply the difference between the elevation of two points either in survey units or factored to the units selected for a traverse.
If you enter curve data, like a radius, arc length or tangent length, the appropriate factoring is applied so that they compute the correct grid coordinates but the distances themselves match the distance type of the traverse. For example, if you have selected any Ground Distance type for the traverse, the radius and arc lengths displayed will be Ground Distance. The computed curve points like the PT (Point of Tangency) however, will be computed on the plane coordinate grid for your CRS.
In this way, any curve/spiral information can be displayed as a ground or geodetic distance and any curve/spiral points can be converted to an equivalent geodetic position for stakeout using GPS.
Stationing is always displayed in the distance type of the traverse. If you are displaying Grid Distance, then stationing will be in grid distance. If you are displaying Ground Distance (at project elevation), then stationing will be of that ground type. In this way, stationing will always match the accumulation of individual course distances displayed in the traverse view.
When you recall points into a Traverse View, TPC inverses the grid coordinate distance or geodetic distance on the ellipsoid surface and factors it according to the distance type you have selected for that traverse. So you can have the traverse display any distance type you want.
Note: You will want to consider the coordinates and geodetic positions of survey points as independent from the relationships displayed between them in TPC's views and COGO dialogs. Coordinates are ALWAYS in the units of the survey (feet, meters, chains, etc). Within a traverse, a drawing or a COGO routine, any distance or direction relationship can be displayed between any two survey points at any time.
Working with Units
Choosing a Survey Grid
Coordinate Distance Types
Geodetic Distance Types
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