TopographyDataset
A metatype for an ordered set of topography data.
Attributes
| Name | Type | Description |
|---|---|---|
| [i] | TopographyData | The ith data member of the set. |
Note
The structure of the set cannot be modified. The properties of its members
are mutable however, e.g. their offset. The set also supports addition and
subtraction operations with a number resulting in all its data members
being offset.
Constructor
A TopographyDataset represents an union of various data
referering to a same topography. It behaves as a
TopographyData but considering the best data available in
its set. The constructor takes a table of data as argument or a variable
number of data arguments. Each data element can be either a
TopographyData object or one of its
constructor arguments, i.e. a path string
or an offset number for a geoid. The order in which the data elements are
specified in the constructor does matter. Elements defined first have
precedence, e.g. when requesting the topography elevation.
Note
When providing a TopographyData argument a shallow copy is done. The set instance refers to the same input data but with an independent offset.
Synopsis
pumas.TopographyDataset(data, ...)
pumas.TopographyDataset{data, ...}
Arguments
| Name | Type | Description |
|---|---|---|
| data | number, string or TopographyData |
TopographyData or any argument refering to them as defined in the TopographyData constructor. |
See also
TopographyDataset.clone
Get a shallow copy of the TopographyDataset. The cloned data members to the same data than in the initial set but with independent offsets. In order to get a deep copy of the data one should instead create a new instance with the constructor.
Synopsis
TopographyDataset:clone()
Arguments
None, except self.
Returns
| Type | Description |
|---|---|
| TopographyDataset | Shallow copy of the topography dataset. |
See also
TopographyDataset.elevation
Get the topography elevation at an Earth location using the first matching data of the set. The input location can be specified by providing its latitude and longitude or by providing a point instance (e.g. GeodeticPoint, CartesianPoint), as detailed in the synopsis below.
Synopsis
TopographyDataset:elevation(coordinates)
TopographyDataset:elevation(latitude, longitude)
Arguments
| Name | Type | Description |
|---|---|---|
| coordinates | Coordinates | Point coordinates, in m. |
| latitude | number |
Latitude, in deg. |
| longitude | number |
Longitude, in deg. |
Returns
| Type | Description |
|---|---|
number or nil |
Topography elevation, in m, or nil if there are no data in the set for the requested location. |
Note
Topography data are usually provided w.r.t. the sea level. In order to get the altitude w.r.t. the WGS84 ellipsoid (e.g. the GPS altitude) one needs to correct from the geoid undulations.