Tipper

Tipper#

This object can be used to store tipper (ZTEM) surveys - a natural-source geophysical method. Data are provided in the frequency-domain as point source measurements of tipper data.

The following example shows how to generate a tipper survey with associated data stored in geoh5 format and accessible from Geoscience ANALYST.

mtSurvey

import numpy as np

from geoh5py.objects import TipperBaseStations, TipperReceivers
from geoh5py.workspace import Workspace


# Create a new project
workspace = Workspace("my_project.geoh5")

# Define the pole locations
n_stations = 64
n_lines = 2
x_loc, y_loc = np.meshgrid(
    np.linspace(0, 60, n_stations), np.linspace(-20, 20.0, n_lines)
)
vertices = np.c_[x_loc.ravel(), y_loc.ravel(), np.zeros_like(x_loc).ravel()]

# Assign a line ID to the poles (vertices)
parts = np.kron(np.arange(n_lines), np.ones(n_stations)).astype("int")

# Create the survey from vertices
receivers = TipperReceivers.create(workspace, vertices=vertices, parts=parts)
base = TipperBaseStations.create(workspace, vertices=vertices)

/home/docs/checkouts/readthedocs.org/user_builds/mirageoscience-geoh5py/conda/latest/lib/python3.10/site-packages/geoh5py/workspace/workspace.py:1105: UserWarning: From version 0.8.0, the 'h5file' attribute must be a string or path to an existing file, or user must call the 'create' method. We will attempt to `save` the file for you, but this behaviour will be removed in future releases.
  warnings.warn(

We have so far created two seperate entities, one for the receiver locations and another for the base station(s). In order to finalize the survey, the association must be made between the two entities:

receivers.base_station = base

or equivalently

base.receivers = receivers

Only one of the two options above is needed.

Metadata#

Along with the TipperReceivers, the metadata contains all the necessary information to define the geophysical experiment.

receivers.metadata

{'EM Dataset': {'Base stations': UUID('4501f049-e9a7-48b4-a4b8-650363e3cd9e'),
  'Channels': [],
  'Input type': 'Rx and base stations',
  'Property groups': [],
  'Receivers': UUID('8ee1bbb1-bb1e-4f15-a695-d5f8f445b941'),
  'Survey type': 'ZTEM',
  'Unit': 'Hertz (Hz)'}}

Channels#

List of frequencies at which the data are provided.

receivers.channels = [30.0, 45.0, 90.0, 180.0, 360.0, 720.0]

Input type#

Generic label used in the geoh5 standard for all EM survey entities. Restricted to Rx and base station in the case of a tipper survey.

Property groups#

List of PropertyGroups defining the various data components (e.g. Txz (real), Tyz (imag), …). It is not required to supply all components of the impedence tensor, but it is expected that each component contains a list of data channels of length and in the same order as the Channels (one Data per frequency).

The class method add_components_data can help users add data from nested dictionaries. Below is an example using four components:

# Arbitrary data generator using sine functions
def data_fun(c, f):
    return (c + 1.0) * (f + 1.0) * np.sin(f * np.pi * (x_loc * y_loc).ravel() / 400.0)


# Create a nested dictionary of component and frequency data.
data = {
    component: {
        f"{component}_{freq}": {"values": data_fun(cc, ff)}
        for ff, freq in enumerate(receivers.channels)
    }
    for cc, component in enumerate(
        [
            "Txz (real)",
            "Txz (imaginary)",
            "Tyz (real)",
            "Tyz (imaginary)",
        ]
    )
}

receivers.add_components_data(data)

[<geoh5py.groups.property_group.PropertyGroup at 0x7734f077e6b0>,
 <geoh5py.groups.property_group.PropertyGroup at 0x7734fa147b80>,
 <geoh5py.groups.property_group.PropertyGroup at 0x7734f0358d60>,
 <geoh5py.groups.property_group.PropertyGroup at 0x7734fa1453c0>]

Metadata are updated immediately to reflect the addition of components:

receivers.metadata

{'EM Dataset': {'Base stations': UUID('4501f049-e9a7-48b4-a4b8-650363e3cd9e'),
  'Channels': [30.0, 45.0, 90.0, 180.0, 360.0, 720.0],
  'Input type': 'Rx and base stations',
  'Property groups': ['Txz (real)',
   'Txz (imaginary)',
   'Tyz (real)',
   'Tyz (imaginary)'],
  'Receivers': UUID('8ee1bbb1-bb1e-4f15-a695-d5f8f445b941'),
  'Survey type': 'ZTEM',
  'Unit': 'Hertz (Hz)'}}

Data channels associated with each component can be quickly accessed through the BaseEMSurvey.components property:

receivers.components

{'Txz (real)': [<geoh5py.data.float_data.FloatData at 0x7734f077f040>,
  <geoh5py.data.float_data.FloatData at 0x7734f825e0b0>,
  <geoh5py.data.float_data.FloatData at 0x7734fa11bd60>,
  <geoh5py.data.float_data.FloatData at 0x7734f077e500>,
  <geoh5py.data.float_data.FloatData at 0x7734f077e950>,
  <geoh5py.data.float_data.FloatData at 0x7734f077e860>],
 'Txz (imaginary)': [<geoh5py.data.float_data.FloatData at 0x7734f077e350>,
  <geoh5py.data.float_data.FloatData at 0x7734f077e5f0>,
  <geoh5py.data.float_data.FloatData at 0x7734f077e4d0>,
  <geoh5py.data.float_data.FloatData at 0x7734fa147d30>,
  <geoh5py.data.float_data.FloatData at 0x7734fa147cd0>,
  <geoh5py.data.float_data.FloatData at 0x7734fa146680>],
 'Tyz (real)': [<geoh5py.data.float_data.FloatData at 0x7734f077e020>,
  <geoh5py.data.float_data.FloatData at 0x7734fa144490>,
  <geoh5py.data.float_data.FloatData at 0x7734f03589a0>,
  <geoh5py.data.float_data.FloatData at 0x7734f0358a60>,
  <geoh5py.data.float_data.FloatData at 0x7734f0358b20>,
  <geoh5py.data.float_data.FloatData at 0x7734f0358c40>],
 'Tyz (imaginary)': [<geoh5py.data.float_data.FloatData at 0x7734f077e260>,
  <geoh5py.data.float_data.FloatData at 0x7734f03599f0>,
  <geoh5py.data.float_data.FloatData at 0x7734f0359a50>,
  <geoh5py.data.float_data.FloatData at 0x7734fa145870>,
  <geoh5py.data.float_data.FloatData at 0x7734fa145420>,
  <geoh5py.data.float_data.FloatData at 0x7734fa1445e0>]}

Receivers#

Generic label used in the geoh5 standard for EM survey to identify the TipperReceivers entity.

Base stations#

Generic label used in the geoh5 standard for EM survey to identify the TipperBaseStations entity.

Survey type#

Label identifier for ZTEM survey type.

Unit#

Units for frequency sampling of the data: Hertz (Hz), KiloHertz (kHz), MegaHertz (MHz) or Gigahertz (GHz).

workspace.finalize()
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