geosoft.gxpy.ipj submodule

class geosoft.gxpy.ipj.GXipj

Bases: object

Class to work with Geosoft coordinate systems. This class wraps many of the functions found in geosoft.gxapi.GXIPJ.

._ipj is the GXIPJ handle to use when calling GXIPJ methods directly

Constructors:

from_name:from a name string from_gxf:from a list of GXF strings from_dict:from a dictionary from_json:from a json string from_esri:from an ESRI wkt string

New in version 9.1.

static compare(ipj1, ipj2)

Returns:

True if two projections are the same

Parameters:

• ipj1 – GXipj
• ipj2 – GXipj

New in version 9.1.

dict()

Return IPJ dictionary

New in version 9.1.

classmethod from_dict(ipj_dict)

Create an IPJ from a ipj_dict

Parameters:ipj_dict – IPJ dictionary, or a valid name string

New in version 9.1.

classmethod from_esri(esri_str)

Create an IPJ from an ESRI wkt coordinate string

Parameters:esri_str – ESRI coordinate definition string

New in version 9.1.

classmethod from_gxf(gxfs)

Create IPJ from a set of GXF strings.

Params:gxfs: list of GXF strings. See GXFIPJ.set_gxf() reference.

New in version 9.1.

classmethod from_json(jstr)

Create an IPJ from a string, which can be a valid coordinate system name string or a JSON format string that defines the coordinate system type and properties as follows:

LocalGrid:

A local grid requires only the latitude and longitude of the local grid origin, though generally an azimuth of rotation the local grid axis with respect to true North is generally expected. Other properties may also be specified if further detail is known or desired. An “Oblique Stereographic” coordinate system is constructed centred on the local grid origin such that the stereographic plan touches the elipsoid of the earth at that point. The “scalefactor” can be used to adjust for intended area of use. The default scale factor ensures length units are comparable to UTM length units (0.9996).

{   "type": "LocalGrid"
    "properties": {
        "latitude": value or string in form "(+/-) deg.mm.ss.ss (N/S)"
        "longitude: value or string
        "azimuth": value (rotation in degrees azimuth, default is 0.0)
        "elevation": value (elevation of map plane, default is 0.0)
        "datum": string (name of the datum, default is "WGS 84")
        "ldatum": string (local datum transform, default determined from datum)
        "units": string (unit name, default is "m")
        "scalefactor": value (central scale factor, default is 0.9996)
     }
}

EPSG:

(http://spatialreference.org/)

{   "type": "EPSG"
    "properties": {
        "code": EPSG_code_number
    },
    "orientation": "<x0,y0,z0,xR,yR,zR>"
}

Geosoft:

(http://www.geosoft.com/resources/goto/GXF-Grid-eXchange-File)

{   "type": "Geosoft",
    "properties": {
        "name": name
        "datum": datum
        "method": method
        "units": units
        "local_datum": local datum transform
    },
    "orientation": "<x0,y0,z0,xR,yR,zR>"
}

See see http://www.geosoft.com/resources/goto/GXF-Grid-eXchange-File for GXF string reference

ESRI:

(http://webhelp.esri.com/arcgisserver/9.3/java/index.htm#geodatabases/the_ogc-607957855.htm)

{   "type": "ESRI",
    "properties": {
        "wkt": wkt format string, starts with "PROJCS[" or "GEOGCS["
    },
    "orientation": "<x0,y0,z0,xR,yR,zR>"
}

“orientation”:

Note

Only orientations of “<0, 0, 0, 0, 0, 0>” are supported in version 9.1. Oriented coordinate systems will be added at some point in the future. Oriented coordinates can be achieved using Oblique Stereographic.

FUTURE: In Geosoft coordinate systems, a cartesian system can be oriented arbitrarily in three dimensions relative to a base coordinate system. This requires the definition of the local origin location on the base system, and the rotation in degrees clockwise (azimuth in plan view) around each of the three base system axis, as defined by the “orientation” description, which is a set of 6 values within angle brackets:

"<oX,oY,oZ,rX,rY,rX>"

The orientation string can be appended to the name, or added as it’s own key “orientation”

For example, a local grid with origin at (550000,6250000) rotated at azimuth 15 degrees (clockwise) from the base “UTM zone 15N” Northings and Eastings on “WGS 84” would be:

{"type":"Geosoft","properties":{"name":"WGS 84 / UTM zone 15N <550000,6250000,0,0,0,15>"}}

or:

{"type":"Geosoft","properties":{"name":"WGS 84 / UTM zone 15N"},
                                "orientation":"<550000,6250000,0,0,0,15>"}

New in version 9.1.

classmethod from_name(name)

Create an IPJ from a projection name in the form “datum / projection <orientation>”.

Parameters:name – coordinate system name in the form “datum / projection <orientation>”

New in version 9.1.

name(what=None)

Return requested name.

Parameters:what –

gxipj.NAME

gxipj.NAME_PCS

gxipj.NAME_PROJECTION

gxipj.NAME_METHOD

gxipj.NAME_DATUM

gxipj.NAME_ELLIPSOID

gxipj.NAME_LDATUM

gxipj.NAME_UNIT

gxipj.NAME_UNIT_FULL

gxipj.NAME_TYPE

gxipj.NAME_LLDATUM

gxipj.NAME_METHOD_PARMS

gxipj.NAME_METHOD_LABEL

gxipj.NAME_DATUM_PARMS

gxipj.NAME_LDATUM_PARMS

gxipj.NAME_GEOID

gxipj.NAME_LDATUMDESCRIPTION

gxipj.NAME_METHOD_PARMS_NATIVE

gxipj.NAME_ORIENTATION

If ‘what’ is not specified, gxipj.NAME assumed, which returns the coordinate system display name.

Returns:The name requested

New in version 9.1.

static names(what, datum_filter='')

Get a list of coordinate system names

Parameters:

• what –
  gxipj.LIST_COORDINATESYSTEM

  gxipj.LIST_DATUM

  gxipj.LIST_PROJECTION

  gxipj.LIST_UNITS

  gxipj.LIST_LOCALDATUMDESCRIPTION

  gxipj.LIST_LOCALDATUMNAME

  gxipj.LIST_UNITSDESCRIPTION
• datum_filter – name of a datum to filter results

Returns:

sorted list of names

New in version 9.1.

to_gxf()

Get GXF string list from ipj. Returns list of 5 GXF strings.

New in version 9.1.

to_json()

Return a JSON formatted projection in the form:

{
   "baseName": "DHDN / Okarito 2000",
   "datumName": "DHDN",
   "localDatumName": "DHDN to WGS 84 (1)",
   "name": "DHDN / Okarito 2000 <25000,1000000,50,90,0,15>",
   "orientation": "<25000,1000000,50,90,0,15>",
   "projectionName": "Okarito 2000",
   "projectionType": "Transverse Mercator",
   "properties": {
      "datum": "DHDN,6377397.155,0.0816968312225275,0",
      "local_datum": ""DHDN to WGS 84 (1)",582,105,414,1.04,0.35,-3.08,8.29999999996112",
      "name": "DHDN / Okarito 2000 <25000,1000000,50,90,0,15>",
      "projection": ""Transverse Mercator",-43.11,170.260833333333,1,400000,800000",
      "units": "m,1"
   },
   "type": "Geosoft",
   "unitName": "m"
}

New in version 9.1.

units()

Returns:tuple (factor, abbreviation), where factor is multiplier to convert to metres

New in version 9.1.

class geosoft.gxpy.ipj.GXpj(ipj_from, ipj_to)

Bases: object

Class to reproject coordinates.

Params ipj_from:  GXipj from coordinate system Params ipj_to:GXipj to coordinate system

New in version 9.1.

convert(xyz)

Project data in array in which first columns are x,y or x,y,z.

Coordinates are reprojected in-place.

Parameters:

xyz –

numpy array shape (,3+) for (x,y,z) conversion

numpy array shape (,2) for x,y conversion

Example:

Given an array shape (500,6), which represents 500 data records with 6 columns in which the first 3 columns are coordinates X, Y and Z.

data = np.zeros((10,5), dtype='float') #then fill the array with some data

pj.convert(data[:,2])       #transform x,y
pj.convert(data[:,3])       #transform x,y and z
pj.convert(data)            #transform x,y and z (same as previous line)

New in version 9.1.

exception geosoft.gxpy.ipj.IPJException

Bases: Exception

Exceptions from this module.

New in version 9.1.