Class: Proj::Conversion

Inherits:
PjObject show all
Includes:
CoordinateOperationMixin
Defined in:
lib/proj/conversion.rb

Overview

Conversions are coordinate operations that convert a source coordinate to a new value. In Proj they are defined as operations that do not exert a change in reference frame while {Transformation transformations } do.

Class Method Summary collapse

Instance Method Summary collapse

Methods included from CoordinateOperationMixin

#accuracy, #ballpark_transformation?, #create_inverse, #forward, #grid, #grid_count, #instantiable?, #inverse, #last_used_operation, #method_auth_name, #method_code, #method_name, #normalize_for_visualization, #param, #param_count, #param_index, #roundtrip, #step, #step_count, #to_wgs84, #transform, #transform_array, #transform_bounds

Methods inherited from PjObject

#accuracy, #angular_input?, #angular_output?, #area_of_use, #auth, #auth_name, #context, #context=, create, create_from_database, create_from_name, create_from_wkt, #definition, #degree_input?, #degree_output?, #deprecated?, #description, #equivalent_to?, #errno, #errorno, #factors, #geod_distance, #has_inverse?, #id, #id_code, #info, #initialize_copy, #lp_distance, #lpz_distance, #name, #non_deprecated, #proj_type, #remarks, #scope, #source_crs, #target_crs, #to_json, #to_proj_string, #to_ptr, #to_s, #to_wkt, #xy_distance, #xyz_distance

Constructor Details

#initialize(value, context = nil) ⇒ Conversion

Instantiates an conversion from a string. The string can be:

  • proj-string,

  • WKT string,

  • object code (like “EPSG:4326”, “urn:ogc:def:crs:EPSG::4326”, “urn:ogc:def:coordinateOperation:EPSG::1671”),

  • Object name. e.g “WGS 84”, “WGS 84 / UTM zone 31N”. In that case as uniqueness is not guaranteed, heuristics are applied to determine the appropriate best match.

  • OGC URN combining references for compound coordinate reference systems (e.g “urn:ogc:def:crs,crs:EPSG::2393,crs:EPSG::5717” or custom abbreviated syntax “EPSG:2393+5717”),

  • OGC URN combining references for concatenated operations (e.g. “urn:ogc:def:coordinateOperation,coordinateOperation:EPSG::3895,coordinateOperation:EPSG::1618”)

  • PROJJSON string. The jsonschema is at proj.org/schemas/v0.4/projjson.schema.json (added in 6.2)

  • compound CRS made from two object names separated with “ + ”. e.g. “WGS 84 + EGM96 height” (added in 7.1)

Parameters:

  • value (String) —

    . See above

See Also:



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# File 'lib/proj/conversion.rb', line 54

def initialize(value, context=nil)
  context ||= Context.current
  ptr = Api.proj_create(context, value)

  if ptr.null?
    Error.check_context(context)
  end

  if Api.method_defined?(:proj_is_crs) && Api.proj_is_crs(ptr)
    raise(Error, "Invalid conversion. Proj created an instance of: #{self.proj_type}.")
  end

  super(ptr, context)
end

Class Method Details

.create_conversion(context, name:, auth_name:, code:, method_name:, method_auth_name:, method_code:, params:) ⇒ Conversion

Create a Transformation

Parameters:

  • context (Context) —

    Context

  • name (String) —

    Name of the transformation. Default is nil.

  • auth_name (String) —

    Transformation authority name. Default is nil.

  • code (String) —

    Transformation code. Default is nil.

  • method_name (String) —

    Method name. Default is nil.

  • method_auth_name (String) —

    Method authority name. Default is nil.

  • method_code (String) —

    Method code. Default is nil.

  • params (Array<Parameter>) —

    Parameter descriptions

Returns:



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# File 'lib/proj/conversion.rb', line 25

def self.create_conversion(context, name:, auth_name:, code:, method_name:, method_auth_name:, method_code:, params:)
  params_ptr = FFI::MemoryPointer.new(Api::PJ_PARAM_DESCRIPTION, params.size)
  params.each_with_index do |param, i|
    param_description_target = Api::PJ_PARAM_DESCRIPTION.new(params_ptr[i])
    param_description_source = param.to_description
    param_description_target.to_ptr.__copy_from__(param_description_source.to_ptr, Api::PJ_PARAM_DESCRIPTION.size)
  end

  pointer = Api.proj_create_conversion(context, name, auth_name, code, method_name, method_auth_name, method_code, params.size, params_ptr)
  Error.check_context(context)
  self.create_object(pointer, context)
end

Instance Method Details

#convert_to_other_method(new_method_epsg_code: nil, new_method_name: nil) ⇒ Conversion

Return an equivalent projection. Currently implemented:

  • EPSG_CODE_METHOD_MERCATOR_VARIANT_A (1SP) to EPSG_CODE_METHOD_MERCATOR_VARIANT_B (2SP)

  • EPSG_CODE_METHOD_MERCATOR_VARIANT_B (2SP) to EPSG_CODE_METHOD_MERCATOR_VARIANT_A (1SP)

  • EPSG_CODE_METHOD_LAMBERT_CONIC_CONFORMAL_1SP to EPSG_CODE_METHOD_LAMBERT_CONIC_CONFORMAL_2SP

  • EPSG_CODE_METHOD_LAMBERT_CONIC_CONFORMAL_2SP to EPSG_CODE_METHOD_LAMBERT_CONIC_CONFORMAL_1SP

Parameters:

  • new_method_epsg_code (String) (defaults to: nil) —

    EPSG code of the target method. Or nil in which case new_method_name must be specified.

  • new_method_name (String) (defaults to: nil) —

    EPSG or PROJ target method name. Or nil in which case new_method_epsg_code must be specified

Returns:



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# File 'lib/proj/conversion.rb', line 79

def convert_to_other_method(new_method_epsg_code: nil, new_method_name: nil)
  ptr = Api.proj_convert_conversion_to_other_method(self.context, self,
                                                    new_method_epsg_code ? new_method_epsg_code: 0,
                                                    new_method_name)

  if ptr.null?
    Error.check_context(context)
  end

  self.class.create_object(ptr, context)
end