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.
from pathlib import Path
import numpy as np
from geoh5py.objects import TipperBaseStations, TipperReceivers
from geoh5py.workspace import Workspace
# Create a new project
h5file = Path("my_project.geoh5")
workspace = Workspace(h5file) if h5file.exists() else Workspace.create(h5file)
# 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)
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 geoh5py.objects.surveys.electromagnetics.tipper.TipperReceivers, the metadata contains all the necessary information to define the geophysical experiment.
receivers.metadata
{'EM Dataset': {'Base stations': UUID('ece7b4c7-d7df-4b97-ba97-3623033a525a'),
'Channels': [],
'Input type': 'Rx and base stations',
'Property groups': [],
'Receivers': UUID('f154901c-49ab-4b41-834b-5416e97334c4'),
'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 geoh5py.groups.property_group.PropertyGroup instances 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 geoh5py.objects.surveys.electromagnetics.base.BaseEMSurvey.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 0x7107e6abbe30>,
<geoh5py.groups.property_group.PropertyGroup at 0x7107e6910aa0>,
<geoh5py.groups.property_group.PropertyGroup at 0x7107e6912390>,
<geoh5py.groups.property_group.PropertyGroup at 0x7107e6913590>]
Metadata are updated immediately to reflect the addition of components:
receivers.metadata
{'EM Dataset': {'Base stations': UUID('ece7b4c7-d7df-4b97-ba97-3623033a525a'),
'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('f154901c-49ab-4b41-834b-5416e97334c4'),
'Survey type': 'ZTEM',
'Unit': 'Hertz (Hz)'}}
Data channels associated with each component can be quickly accessed through the geoh5py.objects.surveys.electromagnetics.base.BaseEMSurvey.components() property:
receivers.components
{'Txz (real)': [<geoh5py.data.float_data.FloatData at 0x7107e6a102c0>,
<geoh5py.data.float_data.FloatData at 0x7108343e3d70>,
<geoh5py.data.float_data.FloatData at 0x7107e6c611f0>,
<geoh5py.data.float_data.FloatData at 0x7107e7a41970>,
<geoh5py.data.float_data.FloatData at 0x7107e6a753a0>,
<geoh5py.data.float_data.FloatData at 0x7107e6abbe90>],
'Txz (imaginary)': [<geoh5py.data.float_data.FloatData at 0x71083457e270>,
<geoh5py.data.float_data.FloatData at 0x7107e7db0b00>,
<geoh5py.data.float_data.FloatData at 0x710825f1c470>,
<geoh5py.data.float_data.FloatData at 0x710825f1d820>,
<geoh5py.data.float_data.FloatData at 0x710825f1d610>,
<geoh5py.data.float_data.FloatData at 0x7107e6910b00>],
'Tyz (real)': [<geoh5py.data.float_data.FloatData at 0x7107e6b5fe30>,
<geoh5py.data.float_data.FloatData at 0x7107e6911df0>,
<geoh5py.data.float_data.FloatData at 0x7107e6911e20>,
<geoh5py.data.float_data.FloatData at 0x7107e6912090>,
<geoh5py.data.float_data.FloatData at 0x7107e6912120>,
<geoh5py.data.float_data.FloatData at 0x7107e6912300>],
'Tyz (imaginary)': [<geoh5py.data.float_data.FloatData at 0x7107e6abb680>,
<geoh5py.data.float_data.FloatData at 0x7107e6912fc0>,
<geoh5py.data.float_data.FloatData at 0x7107e6913080>,
<geoh5py.data.float_data.FloatData at 0x7107e69131d0>,
<geoh5py.data.float_data.FloatData at 0x7107e6913320>,
<geoh5py.data.float_data.FloatData at 0x7107e6abb290>]}
Receivers#
Generic label used in the geoh5 standard for EM survey to identify the geoh5py.objects.surveys.electromagnetics.tipper.TipperReceivers entity.
Base stations#
Generic label used in the geoh5 standard for EM survey to identify the geoh5py.objects.surveys.electromagnetics.tipper.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()