GXTIN class¶

class GXTIN(handle=0)[source]¶

GXTIN class.

The GXTIN class calculates the Delaunay triangulation of the positions in a database. This is the “best” set of triangles that can be formed from irregularly distributed points. The serialized GXTIN files can be used for gridding using the Tin-based Nearest Neighbour Algorithm, or for plotting the Delaunay triangles or Voronoi cells to a map.

__init__(handle=0)[source]¶

copy(source)[source]¶

Parameters:: source (GXTIN) – Source GXTIN

New in version 5.0.

License: Geosoft End-User License

classmethod create(vv_x, vv_y, vv_z)[source]¶

This method creates a GXTIN object.

Parameters:

vv_x (GXVV) – X positions
vv_y (GXVV) – Y positions
vv_z (GXVV) – Z values (optional)

Returns:

GXTIN Object

Return type:

New in version 5.0.

License: Geosoft End-User License

Note: CreateTIN does the GXTIN calculation. The Z values are not required, and a 0-length GXVV can be used to indicate the values are not to be used.

classmethod create_s(bf)[source]¶

Create GXTIN from a serialized source

Parameters:: bf (GXBF) – GXBF from which to read GXTIN
Returns:: GXTIN Object
Return type:: GXTIN

New in version 5.0.

License: Geosoft End-User License

classmethod export_xml(tin, crc, file)[source]¶

Export a GXTIN object as XML

Parameters:

tin (str) – GXTIN file
crc (int_ref) – CRC returned (Currently this is not implemented)
file (str) – Output XML file

New in version 6.0.1.

License: Geosoft End-User License

get_convex_hull(ply)[source]¶

Get the convex hull of the GXTIN.

Parameters:: ply (GXPLY) – GXPLY object

New in version 5.0.

License: Geosoft End-User License

Note: The convex hull is the outside boundary of the triangulated region.

get_ipj(ipj)[source]¶

Get the projection.

Parameters:: ipj (GXIPJ) – GXIPJ in which to place the GXTIN projection

New in version 5.0.3.

License: Geosoft End-User License

get_joins(vv_joins, vv_index, vv_num)[source]¶

Get joins from a GXTIN mesh.

Parameters:

vv_joins (GXVV) – Joins GXVV (adjacent nodes)
vv_index (GXVV) – Index GXVV
vv_num (GXVV) – Number GXVV

New in version 5.0.

License: Geosoft End-User License

Note: The join information is returned in three VVs.

The joins GXVV is a list off the adjacent nodes for each node, arranged for 1st node, 2nd node etc.

The index GXVV gives the starting index in the joins GXVV for the adjacent nodes to each node.

The number GXVV gives the number of adjacent nodes for each node.

All VVs must be type GS_LONG.

get_mesh(vv)[source]¶

Get lines from a GXTIN mesh.

Parameters:: vv (GXVV) – GXVV of type GS_D2LINE (returned)

New in version 5.0.

License: Geosoft End-User License

get_nodes(vvx, vvy, vvz)[source]¶

Get the X,Y locations and Z values of the GXTIN nodes.

Parameters:

vvx (GXVV) – X GXVV
vvy (GXVV) – Y GXVV
vvz (GXVV) – Z GXVV

New in version 5.0.

License: Geosoft End-User License

Note: If this is not a Z-valued GXTIN, the Z values will be dummies.

get_triangle(index, x0, y0, x1, y1, x2, y2)[source]¶

Get the locations of the vertices of a specific triangle

Parameters:

index (int) – Triangle index [0…N-1]
x0 (float_ref) – X0
y0 (float_ref) – Y0
x1 (float_ref) – X1
y1 (float_ref) – Y1
x2 (float_ref) – X2
y2 (float_ref) – Y2

New in version 5.0.

License: Geosoft End-User License

get_triangles(tri_vv_pt1, tri_vv_pt2, tri_vv_pt3)[source]¶

Get the triangle nodes.

Parameters:

tri_vv_pt1 (GXVV) – Node 1 GXVV
tri_vv_pt2 (GXVV) – Node 2 GXVV
tri_vv_pt3 (GXVV) – Node3 GXVV

New in version 8.4.

License: Geosoft End-User License

get_voronoi_edges(vv)[source]¶

Get line segments defining Voronoi cells.

Parameters:: vv (GXVV) – GXVV of GS_D2LINE type (create with type -32)

New in version 5.0.

License: Geosoft End-User License

interp_vv(vvx, vvy, vvz)[source]¶

Interp TINned values using the natural neighbour method.

Parameters:

vvx (GXVV) – GXVV X locations to interpolate (GS_DOUBLE)
vvy (GXVV) – GXVV Y locations to interpolate (GS_DOUBLE)
vvz (GXVV) – GXVV Interpolated Z values (GS_DOUBLE)

New in version 5.0.

License: Geosoft End-User License

Note: The GXTIN have been created using max length = rDUMMY to ensure that the GXTIN has a convex hull (otherwise the routine that locates the triangle for a given location may fail). The GXTIN must also have been created using the Z values. Values located outside the convex hull are set to rDUMMY. The method is based on the following paper:

Sambridge, M., Braun, J., and McQueen, H., 1995, Geophysical parameterization and interpolation of irregular data using natural neighbours: Geophysical Journal International, 122 p. 837-857.

is_null()[source]¶

Check if this is a null (undefined) instance

Returns:: True if this is a null (undefined) instance, False otherwise.
Return type:: bool

is_z_valued()[source]¶

Does the GXTIN contain Z values with each X,Y?

Returns:: Returns 1 if Z values are defined in the GXTIN
Return type:: int

New in version 5.0.

License: Geosoft End-User License

linear_interp_vv(vvx, vvy, vvz)[source]¶

Interp TINned values using the linear interpolation

Parameters:

vvx (GXVV) – GXVV X locations to interpolate (GS_DOUBLE)
vvy (GXVV) – GXVV Y locations to interpolate (GS_DOUBLE)
vvz (GXVV) – GXVV Interpolated Z values (GS_DOUBLE)

New in version 5.1.4.

License: Geosoft End-User License

Note: The GXTIN have been created using max length = rDUMMY to ensure that the GXTIN has a convex hull (otherwise the routine that locates the triangle for a given location may fail). The GXTIN must also have been created using the Z values. Values located outside the convex hull are set to rDUMMY.

The values are set assuming that each GXTIN triangle defines a plane.

locate_triangle(t, x, y)[source]¶

Get the index of the triangle containing X, Y.

Parameters:

t (int) – Seed triangle (can be iDummy or <0)
x (float) – Target X location
y (float) – Target Y location

Returns:

The index of the triangle containing X, Y.

Return type:

int

New in version 5.0.

License: Geosoft End-User License

Note: Index returned begins at 0, but could be negative.

-1: If X,Y is not contained in a triangle (or triangle not found)

-2: If the location is on an edge
This is for “fall-back” purposes only.

Frequently edge positions are located as being part of a triangle, so do not rely on this result to determine if a node position is on an edge.

-3: If the location is a vertex.
This is for “fall-back” purposes only in the code. Normal operation is to include a node position inside a triangle, so do not rely on this result to determine if a node position is input.

nearest_vv(vvx, vvy, vvz)[source]¶

Interp TINned values using the nearest neighbour.

Parameters:

vvx (GXVV) – GXVV X locations to interpolate (GS_DOUBLE)
vvy (GXVV) – GXVV Y locations to interpolate (GS_DOUBLE)
vvz (GXVV) – GXVV Interpolated Z values (GS_DOUBLE)

New in version 6.0.

License: Geosoft End-User License

Note: The GXTIN have been created using max length = rDUMMY to ensure that the GXTIN has a convex hull (otherwise the routine that locates the triangle for a given location may fail). The GXTIN must also have been created using the Z values. Values located outside the convex hull are set to rDUMMY.

Within each voronoi triangle, the Z value of node closest to the input X,Y location is returned.

nodes()[source]¶

Returns the number of nodes in the GXTIN

Returns:: The number of nodes in the GXTIN
Return type:: int

New in version 5.0.

License: Geosoft End-User License

classmethod null()[source]¶

A null (undefined) instance of GXTIN

Returns:: A null GXTIN
Return type:: GXTIN

range_xy(x_min, y_min, x_max, y_max)[source]¶

Find the range in X and Y of the TINned region.

Parameters:

x_min (float_ref) – Min X (returned)
y_min (float_ref) – Min Y
x_max (float_ref) – Max X
y_max (float_ref) – Max Y

New in version 5.0.

License: Geosoft End-User License

Note: The TINned range is the range of X and Y covered by the GXTIN triangles. It can thus be less than the full X and Y range of the nodes themselves, if a full convex hull is not calculated.

serial(bf)[source]¶

Serialize GXTIN

Parameters:: bf (GXBF) – GXBF in which to write GXTIN

New in version 5.0.

License: Geosoft End-User License

set_ipj(ipj)[source]¶

Set the projection.

Parameters:: ipj (GXIPJ) – GXIPJ to place in the GXTIN

New in version 5.0.3.

License: Geosoft End-User License

triangles()[source]¶

Returns the number of triangles in the GXTIN.

Returns:: The number of triangles in the GXTIN
Return type:: int

New in version 5.0.

License: Geosoft End-User License